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  • Using SurfaceFormat.Single and HLSL for GPGPU with XNA

    - by giancarlo todone
    I'm trying to implement a so-called ping-pong technique in XNA; you basically have two RenderTarget2D A and B and at each iteration you use one as texture and the other as target - and vice versa - for a quad rendered through an HLSL pixel shader. step1: A--PS--B step2: B--PS--A step3: A--PS--B ... In my setup, both RenderTargets are SurfaceFormat.Single. In my .fx file, I have a tachnique to do the update, and another to render the "current buffer" to the screen. Before starting the "ping-pong", buffer A is filled with test data with SetData<float>(float[]) function: this seems to work properly, because if I render a quad on the screen through the "Draw" pixel shader, i do see the test data being correctly rendered. However, if i do update buffer B, something does not function proerly and the next rendering to screen will be all black. For debug purposes, i replaced the "Update" HLSL pixel shader with one that should simply copy buffer A into B (or B into A depending on which among "ping" and "pong" phases we are...). From some examples i found on the net, i see that in order to correctly fetch a float value from a texture sampler from HLSL code, i should only need to care for the red channel. So, basically the debug "Update" HLSL function is: float4 ComputePS(float2 inPos : TEXCOORD0) : COLOR0 { float v1 = tex2D(bufSampler, inPos.xy).r; return float4(v1,0,0,1); } which still doesn't work and results in a all-zeroes ouput. Here's the "Draw" function that seems to properly display initial data: float4 DrawPS(float2 inPos : TEXCOORD0) : COLOR0 { float v1 = tex2D(bufSampler, inPos.xy).r; return float4(v1,v1,v1,1); } Now: playing around with HLSL doesn't change anything, so maybe I'm missing something on the c# side of this, so here's the infamous Update() function: _effect.Parameters["bufTexture"].SetValue(buf[_currentBuf]); _graphicsDevice.SetRenderTarget(buf[1 - _currentBuf]); _graphicsDevice.Clear(Color.Black); // probably not needed since RenderTargetUsage is DiscardContents _effect.CurrentTechnique = _computeTechnique; _computeTechnique.Passes[0].Apply(); _quadRender.Render(); _graphicsDevice.SetRenderTarget(null); _currentBuf = 1 - _currentBuf; Any clue?

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  • shader coding: calculate screen coordinates of fragment

    - by Jay
    Good morning, I'm new to shader coding and trying to implement some visual effects code in shaders using billboards. (Yes, I couldn't have picked anything harder to start with, but I'm lucky that way) Setup: I have rendered the full screen z depth to an array of floats in a previous pass. In the fragment shader I need the scene depth where the rendered fragment is displayed (to see if it's occluded). I can use tex2d() to get the depth value if I have the screen coordinates of the point being rendered in the fragment shader. Question: In the fragment shader how do you calculate the screen coordinates of the pixel (in the range 0-1.0)? Is the position passed to the fragment shader a pixel offset? If so, I guess it would be: float2( position.x / screen-width, position.y / screen-height ) Thanks for any help/

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  • Geometry instancing in OpenGL ES 2.0

    - by seahorse
    I am planning to do geometry instancing in OpenGL ES 2.0 Basically I plan to render the same geometry(a chair) maybe 1000 times in my scene. What is the best way to do this in OpenGL ES 2.0? I am considering passing model view mat4 as an attribute. Since attributes are per vertex data do I need to pass this same mat4, three times for each vertex of the same triangle(since modelview remains constant across vertices of the triangle). That would amount to a lot of extra data sent to the GPU( 2 extra vertices*16 floats*(Number of triangles) amount of extra data). Or should I be sending the mat4 only once per triangle?But how is that possible using attributes since attributes are defined as "per vertex" data? What is the best and efficient way to do instancing in OpenGL ES 2.0?

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  • Driver error when using multiple shaders

    - by Jinxi
    I'm using 3 different shaders: a tessellation shader to use the tessellation feature of DirectX11 :) a regular shader to show how it would look without tessellation and a text shader to display debug-info such as FPS, model count etc. All of these shaders are initialized at the beginning. Using the keyboard, I can switch between the tessellation shader and regular shader to render the scene. Additionally, I also want to be able toggle the display of debug-info using the text shader. Since implementing the tessellation shader the text shader doesn't work anymore. When I activate the DebugText (rendered using the text-shader) my screens go black for a while, and Windows displays the following message: Display Driver stopped responding and has recovered This happens with either of the two shaders used to render the scene. Additionally: I can start the application using the regular shader to render the scene and then switch to the tessellation shader. If I try to switch back to the regular shader I get the same error as with the text shader. What am I doing wrong when switching between shaders? What am I doing wrong when displaying text at the same time? What file can I post to help you help me? :) thx P.S. I already checked if my keyinputs interrupt at the wrong time (during render or so..), but that seems to be ok Testing Procedure Regular Shader without text shader Add text shader to Regular Shader by keyinput (works now, I built the text shader back to only vertex and pixel shader) (somthing with the z buffer is stil wrong...) Remove text shader, then change shader to Tessellation Shader by key input Then if I add the Text Shader or switch back to the Regular Shader Switching/Render Shader Here the code snipet from the Renderer.cpp where I choose the Shader according to the boolean "m_useTessellationShader": if(m_useTessellationShader) { // Render the model using the tesselation shader ecResult = m_ShaderManager->renderTessellationShader(m_D3D->getDeviceContext(), meshes[lod_level]->getIndexCount(), worldMatrix, viewMatrix, projectionMatrix, textures, texturecount, m_Light->getDirection(), m_Light->getAmbientColor(), m_Light->getDiffuseColor(), (D3DXVECTOR3)m_Camera->getPosition(), TESSELLATION_AMOUNT); } else { // todo: loaded model depends on distance to camera // Render the model using the light shader. ecResult = m_ShaderManager->renderShader(m_D3D->getDeviceContext(), meshes[lod_level]->getIndexCount(), lod_level, textures, texturecount, m_Light->getDirection(), m_Light->getAmbientColor(), m_Light->getDiffuseColor(), worldMatrix, viewMatrix, projectionMatrix); } And here the code snipet from the Mesh.cpp where I choose the Typology according to the boolean "useTessellationShader": // RenderBuffers is called from the Render function. The purpose of this function is to set the vertex buffer and index buffer as active on the input assembler in the GPU. Once the GPU has an active vertex buffer it can then use the shader to render that buffer. void Mesh::renderBuffers(ID3D11DeviceContext* deviceContext, bool useTessellationShader) { unsigned int stride; unsigned int offset; // Set vertex buffer stride and offset. stride = sizeof(VertexType); offset = 0; // Set the vertex buffer to active in the input assembler so it can be rendered. deviceContext->IASetVertexBuffers(0, 1, &m_vertexBuffer, &stride, &offset); // Set the index buffer to active in the input assembler so it can be rendered. deviceContext->IASetIndexBuffer(m_indexBuffer, DXGI_FORMAT_R32_UINT, 0); // Check which Shader is used to set the appropriate Topology // Set the type of primitive that should be rendered from this vertex buffer, in this case triangles. if(useTessellationShader) { deviceContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_3_CONTROL_POINT_PATCHLIST); }else{ deviceContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST); } return; } RenderShader Could there be a problem using sometimes only vertex and pixel shader and after switching using vertex, hull, domain and pixel shader? Here a little overview of my architecture: TextClass: uses font.vs and font.ps deviceContext-VSSetShader(m_vertexShader, NULL, 0); deviceContext-PSSetShader(m_pixelShader, NULL, 0); deviceContext-PSSetSamplers(0, 1, &m_sampleState); RegularShader: uses vertex.vs and pixel.ps deviceContext-VSSetShader(m_vertexShader, NULL, 0); deviceContext-PSSetShader(m_pixelShader, NULL, 0); deviceContext-PSSetSamplers(0, 1, &m_sampleState); TessellationShader: uses tessellation.vs, tessellation.hs, tessellation.ds, tessellation.ps deviceContext-VSSetShader(m_vertexShader, NULL, 0); deviceContext-HSSetShader(m_hullShader, NULL, 0); deviceContext-DSSetShader(m_domainShader, NULL, 0); deviceContext-PSSetShader(m_pixelShader, NULL, 0); deviceContext-PSSetSamplers(0, 1, &m_sampleState); ClearState I'd like to switch between 2 shaders and it seems they have different context parameters, right? In clearstate methode it says it resets following params to NULL: I found following in my Direct3D Class: depth-stencil state - m_deviceContext-OMSetDepthStencilState rasterizer state - m_deviceContext-RSSetState(m_rasterState); blend state - m_device-CreateBlendState viewports - m_deviceContext-RSSetViewports(1, &viewport); I found following in every Shader Class: input/output resource slots - deviceContext-PSSetShaderResources shaders - deviceContext-VSSetShader to - deviceContext-PSSetShader input layouts - device-CreateInputLayout sampler state - device-CreateSamplerState These two I didn't understand, where can I find them? predications - ? scissor rectangles - ? Do I need to store them all localy so I can switch between them, because it doesn't feel right to reinitialize the Direct3d and the Shaders by every switch (key input)?!

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • Something other than Vertex Welding with Texture Atlas?

    - by Tim Winter
    What options (in C# with XNA) would there be for texture usage in a procedural generated 3D world made of cubes to increase performance? Yes, it's like Minecraft. I've been doing a texture atlas and rendering faces individually (4 vertices per face), but I've also read in a couple places about using texture wrapping with two 1D atlases to merge adjacent faces with the same texture. If two or more adjacent faces share the same image, it'd be quite easy to wrap in this way reducing vertices by a large amount. My problem with this is having too many textures, swapping too often, and many image related things like non-power of 2 images. Is there a middle ground option between the 1D texture atlas trick and rendering 4 vertices per cube face? This is a picture of what I have currently (in wireframe). 4 vertices per face seems extremely inefficient to me.

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  • Is there a "golden ratio" in coding?

    - by badallen
    My coworkers and I often come up with silly ideas such as adding entries to Urban Dictionary that are inappropriate but completely make sense if you are a developer. Or making rap songs that are about delegates, reflections or closures in JS... Anyhow, here is what I brought up this afternoon which was immediately dismissed to be a stupid idea. So I want to see if I can get redemptions here. My idea is coming up with a Golden Ratio (or in the neighborhood of) between the number of classes per project versus the number of methods/functions per class versus the number of lines per method/function. I know this is silly and borderline, if not completely, useless, but just think of all the legacy methods or classes you have encountered that are absolutely horrid - like methods with 10000 lines or classes with 10000 methods. So Golden Ratio, anyone? :)

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  • Q&amp;A: What is the UK pricing for the Windows Azure CDN?

    - by Eric Nelson
    The pricing for Windows Azure Content Delivery Network (CDN) was announced last week. The prices are: £0.091 per GB transferred from North America & Europe locations £0.1213 per GB transferred from other locations £0.0061 per 10,000 transactions CDN rates are effective for all billing periods that begin subsequent to June 30, 2010. All usage for billing periods beginning prior to July 1, 2010 will not be charged. To help you determine which pricing plan best suits your needs, please review the comparison table, which includes the CDN information. Steven Nagy has also done an interesting follow up post on CDN. Related Links: Q&A- How can I calculate the TCO and ROI when considering the Windows Azure Platform? Q&A- When do I get charged for compute hours on Windows Azure? Q&A- What are the UK prices for the Windows Azure Platform

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  • How to code a 4x shader/filter which emulates arcade crt display behavior?

    - by Arthur Wulf White
    I want to write a shader/filer probably in adobe Pixel Bender that will do the best job possible in emulating the fill of an oldskul monochromatic arcade CRT screen. Much like this here: http://filthypants.blogspot.com/2012/07/customizing-cgwgs-crt-pixel-shader.html Here are some attributes I know will exist in this filter: It will take in a low res image 160 x 120 and return a medium res image 640 x 480. It will add scanlines It will blur the color channels to create that color bleeding effect It will distort the shape of the image from a perfect rectangle into a rounder shape. The question is, could you please provide any other attributes that are beneficial to emulating an arcade CRT feel and links and resources on coding these effects. Thanks

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  • Expensive HDMI Cables Make No Difference

    - by Jason Fitzpatrick
    While we’re no strangers to spreading the news that expensive HDMI cables are a ripoff, we’re happy to share yet another study that shows there’s zero difference between a $5 cable and a $95 one. Over at the British hardware review site Expert Reviews, they subjected a wide selection of HDMI cables to extensive tests in a bid to produce the end-all examination of whether or not a premium HDMI cable could actually produce a better signal. They used capture cards, pixel-by-pixel comparison of output, and other techniques to pick over individual frames until they ultimately reached the same conclusion everyone outside of the Monster sales staff had already reached: you’re getting absolutely no benefit to spending $100 on cable that can be had for under five bucks. Hit up the link below to read over their methodology. Expensive Cables Make Absolutely No Difference [via Geek News Central] HTG Explains: What Is RSS and How Can I Benefit From Using It? HTG Explains: Why You Only Have to Wipe a Disk Once to Erase It HTG Explains: Learn How Websites Are Tracking You Online

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  • GLSL Bokeh using Quads and Textures

    - by Notoriousaur
    I'm trying to create a depth of field effect with bokeh sprites in GLSL. Specifically, what i would like to do is, for each pixel: See if the pixel is out of the focal range If it is, draw a quad and apply a texture to provide a bokeh sprite. This kind of implementation is seen in the Unreal Engine and by Matt Pettineo, however, both implementations are in DX11 and I'm using OpenGL. I'm a bit stuck on the drawing a quad and applying a texture bit. Does anyone know how I can do this, or provide any relevant links as to how I can do this? Thanks

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  • Oracle Applications Day 2012. Experience the Global Innovation of Management Applications

    - by antonella.buonagurio
    1024x768 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} 1024x768 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} 10 ottobre 2012 – Milano, East End Studios | 17 ottobre 2012 - Roma, Officine Farneto Partecipa all’appuntamento dedicato alla comunità di Clienti e Partner per fare networking e condividere le esperienze sulle soluzioni più innovative per affrontare le sfide attuali e future. Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} A Milano (10/10/2012) interverranno, tra gli altri:  Enrico Ancona, Amministratore Delegato - Imperia & Monferrina e Business Reply  Massimiliano Gerli, CIO - Amplifon e Michele Paolin, Senior Manager - Deloitte eXtended Business Services A Roma (17/10/2012) interverranno, tra gli altri: Giulio Carone, CFO - Enel Green Power e Claudio Arcudi, Senior Executive - Accenture Gianluca D’Aniello, CIO - Sky e Giorgio Pitruzzello, Manager - Deloitte Consulting Spartaco Parente, EPD Change & Label Control - Abbott e Business Reply Sono inoltre previsti i contributi delle aziende Abbott, Aeroporto di Napoli, Amplifon, Dema Aerospace, Enel Green Power, Fiera Milano, Imperia & Monferrina, La Rinascente, Safilo, Sky, Spal,Technogym, Tiscali e Tivù che parleranno di: Innovation for Human Resources Performance Management Excellence Empower Applications with Technology (Milano) Applications for Public Sector (Roma) Next Generation Global Operations Customer Experience Revolution Oltre dieci Instant Workshop ti permetteranno di conoscere e condividere l’esperienza dei Partner e delle aziende che utilizzano le soluzioni Oracle.In più, oltre dieci Instant Workshop per conoscere e condividere l’esperienza dei Partner e delle aziende che utilizzano con successo le soluzioni Oracle. Iscriviti sul sito Partecipa al concorso fotografico Oracle I.M.A.G.E. e vinci il tuo iPad! Scatta le immagini che per te descrivono i cinque concept dell’evento (Innovation, Management, Applications, Global, Experience) e inviale per e-mail. Per iscriverti al contest visita la pagina Concorso sul sito Non perdere l’evento più “social cool” dell’anno!

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  • Ti sei perso l'Oracle EPM Live Webcast sul Project Planning? Ora puoi rivederlo

    - by antonella.buonagurio
    Se non hai potuto seguire l'ultimo webcast EPM dedicato al Project Planning puoi rivederlo a questo link. Il webcast, che fa parte di una serie di live webseminar  dedicati ai professionisti dell'area amministrazione finanza e controllo, è focalizzato sul processo di budgeting, forecasting e controllo di gestione per commessa e delle attività a progetto in ambito economico-finanziario. Durante il webseminar viene presentata  l'integrazione funzionale di Oracle Hyperion EPM System con le altre soluzioni Oracle per il project planning & management. Non perdere l'ultimo appuntamento prima delle vacanze! 13 luglio Oracle EPM Live webcast:  Predictive Planning clicca qui per saperne di più!

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  • Ray Tracing Shadows in deferred rendering

    - by Grieverheart
    Recently I have programmed a raytracer for fun and found it beutifully simple how shadows are created compared to a rasterizer. Now, I couldn't help but I think if it would be possible to implement somthing similar for ray tracing of shadows in a deferred renderer. The way I though this could work is after drawing to the gbuffer, in a separate pass and for each pixel to calculate rays to the lights and draw them as lines of unique color together with the geometry (with color 0). The lines will be cut-off if there is occlusion and this fact could be used in a fragment shader to calculate which rays are occluded. I guess there must be something I'm missing, for example I'm not sure how the fragment shader could save the occlusion results for each ray so that they are available for pixel at the ray's origin. Has this method been tried before, is it possible to implement it as I described and if yes what would be the drawbacks in performance of calculating shadows this way?

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  • Introdução ao NHibernate on TechDays 2010

    - by Ricardo Peres
    I’ve been working on the agenda for my presentation titled Introdução ao NHibernate that I’ll be giving on TechDays 2010, and I would like to request your assistance. If you have any subject that you’d like me to talk about, you can suggest it to me. For now, I’m thinking of the following issues: Domain Driven Design with NHibernate Inheritance Mapping Strategies (Table Per Class Hierarchy, Table Per Type, Table Per Concrete Type, Mixed) Mappings (hbm.xml, NHibernate Attributes, Fluent NHibernate, ConfORM) Supported querying types (ID, HQL, LINQ, Criteria API, QueryOver, SQL) Entity Relationships Custom Types Caching Interceptors and Listeners Advanced Usage (Duck Typing, EntityMode Map, …) Other projects (NHibernate Validator, NHibernate Search, NHibernate Shards, …) ASP.NET Integration ASP.NET Dynamic Data Integration WCF Data Services Integration Comments?

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  • detecting when you are going to reach your hit limit for Google Analytics free account

    - by crmpicco
    I am a user of a free Google Analytics account and i'm slightly concerned that I may be approaching the 10,000,000 hit (Pageviews, Events etc) per month. Google state in their documentation: These limits apply to the Web Property / Property / Tracking ID. 10 million hits per month per property If you go over this limit, the Google Analytics team might contact you and ask you upgrade to Premium or implement client sampling to reduce the amount of data being sent to Google Analytics. However, I note that there is nothing to say that you can review or check up on your current usage for the month. I have administrator access to the Google Analytics account, but I see no feature that lets me check up on my monthly usage. I don't know if Google offer this, either by means of the admin interface or via their support channels - but it would certainly be a useful feature. Is there anyway for a free GA user to obtain this information?

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  • App Fabric Service Bus and Access Control Pricing

    - by kaleidoscope
    The Service Bus costs $3.99 per Connection-month on a consumption basis for individually provisioned connections. Data transfers charges would also apply. Or, if you are able to forecast your needs ahead of time, you can purchase “Packs” of Connections. For example: $9.95 for a pack of 5 Connections, $49.75 for a pack of 25, $199.00 for a pack of 100, or $995 for a pack of 500, plus data transfer charges. Connection Packs represent an effective rate of $1.99 per Connection-month. Access Control will be priced at $1.99 per 100,000 Transactions, which includes token requests and management operations, plus associated data transfer. Typically, Service Bus developers depend on Access Control to secure their Connections. More Information: http://azurefeeds.com/post/865/Announcing_Windows_Azure_platform_commercial_offer_availability_and_updated_AppFabric_pricing.aspx   Amit, S

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  • Resources for 2D rendering using OpenGL?

    - by nightcracker
    I noticed that there is quite some difference between 3D and 2D rendering using OpenGL, the techniques are different - pixel-perfect placing is a lot more desirable, among other things. Are there any good (complete) references on using OpenGL for rendering 2D graphics? There are quite a few "tutorials" around on the net that help you open a window, set up a half-decent environment and draw a sprite, but no real good information on rotation, blending, lightning, drawing order, using the z-buffer, particles, "complex" primitives (circles, stars, cross symbols), ensuring pixel-perfect rendering, instancing and many other staple 2D effects/techniques. Any books, great blogs, anything? Any particular awesome libraries to read?

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  • How do I set up nvidia graphics adapter to put out 1080p, it seems to be using interlace mode>

    - by keepitsimpleengineer
    After upgrading to 12.04, my mythbuntu client/server seems to be running in 1080i, the clue comes from: [ 1176.117] (II) NVIDIA(0): Setting mode "1920x1080_60i" [ 1231.340] (II) NVIDIA(0): Setting mode "DFP-1:1920x1080_60@1920x1080+0+0" This is from Xorg.0.log. This whole thing started from video tearing when watching Mythtv recordings. It didn't happen in 10.10. Should I use "TVStandard" "HD1080p" in the screen section since this is a dedicated HTPC? It only connects to an HDTV (1080p) via hdmi. Here is the current xorg.conf file: # nvidia-settings: X configuration file generated by nvidia-settings # nvidia-settings: version 270.29 (buildd@allspice) Fri Feb 25 14:42:07 UTC 2011 Section "ServerLayout" Identifier "Layout0" Screen 0 "Screen0" 0 0 # commented out by update-manager, HAL is now used and auto-detects devices # Keyboard settings are now read from /etc/default/console-setup # InputDevice "Keyboard0" "CoreKeyboard" # commented out by update-manager, HAL is now used and auto-detects devices # Keyboard settings are now read from /etc/default/console-setup # InputDevice "Mouse0" "CorePointer" Option "Xinerama" "0" EndSection Section "Files" FontPath "unix/:7100" EndSection # commented out by update-manager, HAL is now used and auto-detects devices # Keyboard settings are now read from /etc/default/console-setup #Section "InputDevice" # # generated from default # Identifier "Mouse0" # Driver "mouse" # Option "Protocol" "auto" # Option "Device" "/dev/psaux" # Option "Emulate3Buttons" "no" # Option "ZAxisMapping" "4 5" #EndSection # commented out by update-manager, HAL is now used and auto-detects devices # Keyboard settings are now read from /etc/default/console-setup #Section "InputDevice" # # generated from default # Identifier "Keyboard0" # Driver "kbd" #EndSection Section "Monitor" # HorizSync source: edid, VertRefresh source: edid Identifier "Monitor0" VendorName "Unknown" ModelName "SAMSUNG" HorizSync 26.0 - 81.0 VertRefresh 24.0 - 75.0 Option "DPMS" EndSection Section "Device" Identifier "Device0" Driver "nvidia" VendorName "NVIDIA Corporation" BoardName "GeForce GT 240" Option "TripleBuffer" "1" EndSection Section "Screen" Identifier "Screen0" Device "Device0" Monitor "Monitor0" DefaultDepth 24 Option "TwinView" "0" Option "metamodes" "DFP: nvidia-auto-select +0+0" SubSection "Display" Depth 24 EndSubSection EndSection After a little digging, the question changes slightly, to wit... Per Chapter 19 of nvidia README... "If the EDID for the display device reported a preferred mode timing, and that mode timing is considered a valid mode, then that mode is used as the "nvidia-auto-select" mode." The EDID for my HDMI connected LCD monitor says use first device as preferred. Prefer first detailed timing : Yes Also: (--) NVIDIA(0): EDID maximum pixel clock : 230.0 MHz The list: (from startx -- -verbose 6 ) (--) NVIDIA(0): Detailed Timings: (--) NVIDIA(0): 1920 x 1080 @ 60 Hz (--) NVIDIA(0): Pixel Clock : 148.50 MHz (--) NVIDIA(0): HRes, HSyncStart : 1920, 2008 (--) NVIDIA(0): HSyncEnd, HTotal : 2052, 2200 (--) NVIDIA(0): VRes, VSyncStart : 1080, 1084 (--) NVIDIA(0): VSyncEnd, VTotal : 1089, 1125 (--) NVIDIA(0): H/V Polarity : +/+ This is the actual mode selected: (from xorg.0.log) (--) NVIDIA(0): 1920 x 1080 @ 60 Hz (--) NVIDIA(0): Pixel Clock : 74.18 MHz (--) NVIDIA(0): HRes, HSyncStart : 1920, 2008 (--) NVIDIA(0): HSyncEnd, HTotal : 2052, 2200 (--) NVIDIA(0): VRes, VSyncStart : 1080, 1084 (--) NVIDIA(0): VSyncEnd, VTotal : 1094, 1124 (--) NVIDIA(0): H/V Polarity : +/+ (--) NVIDIA(0): Extra : Interlaced (--) NVIDIA(0): CEA Format : 5 So my HTPC is down-converting to 1080i and then the Monitor is up-converting to 1080p How can I fix this, please?

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  • I manager della logistica a confronto

    - by Paolo Leveghi
    Il 4 di Aprile scorso una quindicina di manager della logistica appartenenti a diversi settori industriali (Retail, Consumer Goods, Natural Resources, etc) si sono ritrovati per un workshop di lavoro oganizzato da Oracle con la collaborazione di Assologistica. Il tema era libero: di cosa avreste bisogno per migliorare la logistica delle vostre aziende?  La discussione è stata viva e durata per più di tre ore. Gli spunti della serata, assieme a quelli che verranno fuori dall'analogo incontro che si svolgerà il 18 Aprile prossimo, saranno parte di una presentazione che verrà preparata da Assologistica e distribuita al suo network.

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  • Innovare e creare valore si può ancora fare?

    - by Silvia Valgoi
    In un momento in cui parole come social networking, Web 2.0, e-commerce, mobilità e multicanalità, cloud computing sono sulla bocca di tutti abbiamo deciso di fermare questo turbinio di bla, bla, bla e prenderci del tempo per condividerne con voi significati ed opportunità. Questi sono gli obiettivi del Sales & Marketing Summit che si terrà il prossimo 28 marzo 2012: Conoscere in anteprima Oracle Fusion CRM, la soluzione di nuova generazione per migliorare e incrementare l'efficacia dei processi di Vendita e Marketing. Scoprire come costruire i processi più innovativi di Customer Experience. Incontrare i nostri esperti e sperimentare le nuove soluzioni di Oracle grazie alle Sessioni Interattive dedicate a Fusion CRM e alla Customer Experience. Confrontarti e condividere idee per innovare   Ti aspettiamo!

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  • how to add water effect to an image

    - by brainydexter
    This is what I am trying to achieve: A given image would occupy say 3/4th height of the screen. The remaining 1/4th area would be a reflection of it with some waves (water effect) on it. I'm not sure how to do this. But here's my approach: render the given texture to another texture called mirror texture (maybe FBOs can help me?) invert mirror texture (scale it by -1 along Y) render mirror texture at height = 3/4 of the screen add some sense of noise to it OR using pixel shader and time, put pixel.z = sin(time) to make it wavy (Tech: C++/OpenGL/glsl) Is my approach correct ? Is there a better way to do this ? Also, can someone please recommend me if using FrameBuffer Objects would be the right thing here ? Thanks

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  • GLSL Shader Effects: How to do motion blur, etc?

    - by DevilWithin
    I am not sure how right it is to ask this question, but still here it goes. I have a full 2D environment, with sprites going around as landscape, characters, etc And to make it more state-of-art looking, i want to implement a motion blur effect, similar to modern FPS's (i.e. crysis) blur when moving fast the camera. In a sidescroller, the desired effect is having this slight blur appearing to give the idea of fast movement, when the camera is moving. If anyone could give me some tips on doing this, im assuming in a pixel shader, i'd be grate. Also, if anyone has other good tips on cool pixel shader effects for 2D games it would be awesome, like some stylizing post fx, such as previous Prince of Persia illustrative style. Thanks

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  • What collision detection approach for top down car game?

    - by nathan
    I have a quite advanced top down car game and i use masks to detect collisions. I have the actual designed track (what the player see) with fancy graphics etc. and two other pictures i use as mask for my detection collisions. Each mask has only two colors, white and black and i check each frame if a pixel of the car collide with a black pixel of the masks. This approach works of course but it's not really flexible. Whenever i want to change the look of a track, i have to redraw the mask and it's a real pain. What is the general approach for this kind of game? How can i improve the flexibility of such a mask based approach?

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  • Height Map Mapping to "Chunked" Quadrilateralized Spherical Cube

    - by user3684950
    I have been working on a procedural spherical terrain generator for a few months which has a quadtree LOD system. The system splits the six faces of a quadrilateralized spherical cube into smaller "quads" or "patches" as the player approaches those faces. What I can't figure out is how to generate height maps for these patches. To generate the heights I am using a 3D ridged multi fractals algorithm. For now I can only displace the vertices of the patches directly using the output from the ridged multi fractals. I don't understand how I generate height maps that allow the vertices of a terrain patch to be mapped to pixels in the height map. The only thing I can think of is taking each vertex in a patch, plug that into the RMF and take that position and translate into u,v coordinates then determine the pixel position directly from the u,v coordinates and determine the grayscale color based on the height. I feel as if this is the right approach but there are a few other things that may further complicate my problem. First of all I intend to use "height maps" with a pixel resolution of 192x192 while the vertex "resolution" of each terrain patch is only 16x16 - meaning that I don't have any vertices to sample for the RMF for most of the pixels. The main reason the height map resolution is higher so that I can use it to generate a normal map (otherwise the height maps serve little purpose as I can just directly displace vertices as I currently am). I am pretty much following this paper very closely. This is, essentially, the part I am having trouble with. Using the cube-to-sphere mapping and the ridged multifractal algorithm previously described, a normalized height value ([0, 1]) is calculated. Using this height value, the terrain position is calculated and stored in the first three channels of the positionmap (RGB) – this will be used to calculate the normalmap. The fourth channel (A) is used to store the height value itself, to be used in the heightmap. The steps in the first sentence are my primary problem. I don't understand how the pixel positions correspond to positions on the sphere and what positions are sampled for the RMF to generate the pixels if only vertices cannot be used.

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