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Search found 1273 results on 51 pages for 'vertex shader'.

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• Hardware instancing for voxel engine

  - by Menno Gouw

  i just did the tutorial on Hardware Instancing from this source: http://www.float4x4.net/index.php/2011/07/hardware-instancing-for-pc-in-xna-4-with-textures/. Somewhere between 900.000 and 1.000.000 draw calls for the cube i get this error "XNA Framework HiDef profile supports a maximum VertexBuffer size of 67108863." while still running smoothly on 900k. That is slightly less then 100x100x100 which are a exactly a million. Now i have seen voxel engines with very "tiny" voxels, you easily get to 1.000.000 cubes in view with rough terrain and a decent far plane. Obviously i can optimize a lot in the geometry buffer method, like rendering only visible faces of a cube or using larger faces covering multiple cubes if the area is flat. But is a vertex buffer of roughly 67mb the max i can work with or can i create multiple?

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• Rendering oily/polluted water?

  - by Fraser

  Any shader wizards out there have an idea of how to achieve an oily/polluted water effect, similar to this: Ideally, the water would not be uniformly oily, but instead the oil could be generated from some source (such as a polluting drain from a chemical plant) and then diffuse throughout the water body. My thought for this part would be to keep an "oil map" as a 2D texture that determines the density of oil at each point on the water surface. It would diffuse and move naturally with the water vel;ocity at that point (I have a wave-particle simulation for dynamic waves, and am already doing something similar for foam on the water surface). However, I'm not sure how physically correct that would be, since oil might not move at the same velocity as the water. And I have no idea how to make all those trippy colors :-). Thoughts?

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• Algorithm for creating spheres?

  - by Dan the Man

  Does anyone have an algorithm for creating a sphere proceduraly with la amount of latitude lines, lo amount of longitude lines, and a radius of r? I need it to work with Unity, so the vertex positions need to be defined and then, the triangles defined via indexes (more info). EDIT I managed to get the code working in unity. But I think I might have done something wrong. When I turn up the detailLevel, All it does is add more vertices and polygons without moving them around. Did I forget something?

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• Radiosity using a hemisphere

  - by P. Avery

  I'm working on a radiosity processor. I'm projecting scene geometry onto a hemisphere at a high order of tessellation during a visibility pass onto a 1024x1024 render target. The problem is that the edges of certain triangles are not being rendered to the item buffer( render target )...so when I test certain edges( or pixels during pixel shader ) for visibility during a reconstruction pass, visible edges are not identified and as a result the pixel for that edge is discarded. One solution was to increase the resolution of the item buffer( up to 4096x4096 )...this helped and more edges were visible, however, this was not fullproof. How do I increase visibility? Here is a screenshot of a scene after radiosity is applied: the seams are edges along a triangle face that were not visible due to the resolution of the item buffer... fixed the problem by sampling the item buffer w/8 points:

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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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• Skip the first RenderTarget when writing to MRT with Opaque blending

  - by cubrman

  I am writing to three rendertargets and whant to know how to tell a GPU not to write to the first RT. When you write a shader you can simply output less data than you have RTs (like output a single float4 when writing to three RTs) and only the first RTs will be affected, but you cannot specify to output this data anywhere else but to COLOR0, then 1, etc. Is there a way to write to several RTs but skip the first target? If I output zeroes, the data in the target will become zeroes, but I need it to remain untuched in the first target and only change in the specified ones. The reason I need this is to prevent data loss when calling SetRendertarget() with DiscardContents RTs. I write to all the RTs at one point and I need to write to only the specified ones afterwards. It must be the first texture as I have a depth buffer linked to it (XNA 4.0). Thanks.

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• Impact of variable-length loops on GPU shaders

  - by Will

  Its popular to render procedural content inside the GPU e.g. in the demoscene (drawing a single quad to fill the screen and letting the GPU compute the pixels). Ray marching is popular: This means the GPU is executing some unknown number of loop iterations per pixel (although you can have an upper bound like maxIterations). How does having a variable-length loop affect shader performance? Imagine the simple ray-marching psuedocode: t = 0.f; while(t < maxDist) { p = rayStart + rayDir * t; d = DistanceFunc(p); t += d; if(d < epsilon) { ... emit p return; } } How are the various mainstream GPU families (Nvidia, ATI, PowerVR, Mali, Intel, etc) affected? Vertex shaders, but particularly fragment shaders? How can it be optimised?

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• Order independent transparency in particle system

  - by Stepan Zastupov

  I'm writing a particle system and would like to find a trick to achieve proper alpha blending without sorting particles because: Each particle is a point sprite in a single mesh and I can't use scene graph ability to sort transparent nodes. The system node should be properly sorted, though. Particle position is computed on shader from initial velocity, acceleration and time. In order to sort the system I would have to perform all this computations on CPU, which is something I want to avoid. Sorting hundreds of particles against camera position and uploading it on GPU each frame seams to be quiet heavy operation. Alpha testing seems to be fast enough on GLES 2.0 and works fine for non-transparent but "masked" textures. Still, it's not enough for semi-transparent particles. How would you handle this?

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• Is a Single Texture Cube Map Possible?

  - by smoth190

  I'm currently developing a test project to explore OpenGL 3 texturing abilities. I have a simple cube, made of 8 vertices and 36 indices. I want each of the cubes faces to have a different texture, so I devised this texture: I made it obvious which sections I want visible (I hope...). In Direct3D, I once made a skybox, and I used a cubemap. However, I had to split it into 6 different textures. This is annoying and hard to manage, it would be nice to have just one texture. Is this even possible? I read somewhere that I could do this by duplicating vertices, is that a good idea? Someone else said I could do it in the shader, but that also baffles me...

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• Drawing an outline around an arbitrary group of hexagons

  - by Perky

  Is there an algorithm for drawing an outline around around an arbitrary group of hexagons? The polygon outline drawn may be concave. See the images below, the green line is what I am trying to achieve. The hexagons are stored as vertices and drawn as polygons. Edit: I've uploaded images that should explain more. I want to favour convex hulls because it's conveys an area of control more quickly. Each hexagon is stored in a multidimensional array so they all have x and y coordinates, I can easily find adjacent hexagons and the opposite vertex, i.e. adjacentHexagon = getAdjacentHexagon( someHexagon, NORTHWEST ) if there isn't a hexagon immediately adjacent it will continue to search in that direction until it finds one or hits the map edges.

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• Water Simulation in LIBGDX [on hold]

  - by Noah Huppert

  I am doing some R&D for a game and am now tackling the topic of water. The goal Make water that can flow. Aka you can have an origin point that water shoots out from or a downhill slope. Make it so water splashes, so when an object hits the water there is a splash. Aka: Actual physics water sim. The current way I know how to do it I know how to create a shader that makes an object look like its water by making waves. Combined with that you can check to see if an object is colliding and apply an upwards force to simulate buoyancy. What is wrong with that way The water does not flow No splashes Possible solutions Have particles that are fairly large that interact with each other to simulate water Possible drawbacks Performance. Question: Is there a better way to do water or is using particles as described the only way?

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• How exactly does XNA's SpriteBatch work?

  - by David Gouveia

  To be more precise, if I needed to recreate this functionality from scratch in another API (e.g. in OpenGL) what would it need to be capable of doing? I do have a general idea of some of the steps, such as how it prepares an orthographic projection matrix and creates a quad for each draw call. I'm not too familiar, however, with the batching process itself. Are all quads stored in the same vertex buffer? Does it need an index buffer? How are different textures handled? If possible I'd be grateful if you could guide me through the process from when SpriteBatch.Begin() is called until SpriteBatch.End(), at least when using the default Deferred mode.

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• D3D9 Alpha Blending on the surfaces

  - by Indeera

  I have a surface (OffScreenPlain or RenderTarget with D3DFMT_A8R8G8B8) which I copy pixels (ARGB) to, from a third party function. Before pixel copying, Bits are accessed by LockRect. This surface is then StretchRect to the Backbuffer which is (D3DFMT_A8R8G8B8). Surface and Backbuffer are different dimensions. Filtering is set to D3DTEXF_NONE. Just after creating the d3d device I've set following RenderState settings D3DRS_ALPHABLENDENABLE -> TRUE D3DRS_BLENDOP -> D3DBLENDOP_ADD D3DRS_SRCBLEND -> D3DBLEND_SRCALPHA D3DRS_DESTBLEND -> D3DBLEND_INVSRCALPHA But I see no alpha blending happening. I've verified that alpha is specified in pixels. I've done a simple test by creating a vertex buffer and drawing a triangle (DrawPrimitive) which displays with alpha blending. In this test surface was StretchRect first and then DrawPrimitive, and the surface content displays without alpha blending and the triangle displays with alpha blending. What am I missing here? Thanks

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• How can I determine if a cube is adjacent to another cube, and optimize its buffers if so?

  - by Christian Frantz

  I'm trying to optimize the rendering of a collection of cubes, (based on an answer I was given to another question I asked). I understand the logic behind occlusion culling, but I'm having trouble with the code. When I create a cube, I want to determine if that cube is touching another existing cube, and if so I don't want to generate the redundant data in my vertex or index buffers. I'm planning on making a method that I call from my cube constructor so that everytime I create a cube, these checks are made, and neither occluded face is ever drawn. How would I go about this?

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• Importing 3d model with multiple skeletons

  - by Sweta Dwivedi

  I have created an animated butterfly in 3ds Max and try to export it in ".fbx" format to use in XNA, however as soon as I compile, i get the following Errors: Warning 1 Multiple skeletons were found in the file. The first skeleton, named "Left.Wing" has been moved to be a child of the scene root. The other, "Right.Wing", will be ignored. Fragment identifier "Right.Wing". Error 2 Vertex is bound to bone "Right.Wing", but this bone is not present in the skeleton. Which is confusing since I have the bone Right.Wing . . and I use it to animate the butterfly I have seen a few possible solution for Blender but none for 3Ds max it would be really helpful if someone could help me out with this

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• Dynamic Quad/Oct Trees

  - by KKlouzal

  I've recently discovered the power of Quadtrees and Octrees and their role in culling/LOD applications, however I've been pondering on the implementations for a Dynamic Quad/Oct Tree. Such tree would not require a complete rebuild when some of the underlying data changes (Vertex Data). Would it be possible to create such a tree? What would that look like? Could someone point me in the correct direction to get started? The application here would, in my scenario, be used for a dynamically changing spherical landscape with over 10,000,000 verticies. The use of Quad/Oct Trees is obvious for Culling & LOD as well as the benefits from not having to completely recompute the tree when the underlying data changes.

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• Sharing VBO with multiple objects and fixed size buffer data

  - by Mark Ingram

  I'm just messing around with OpenGL and getting some basic structures in place and my first attempt resulted in each SceneObject class (just contains vertex information right now) having it's own VBO inside it, however I've read that it might be better to share VBOs across multiple objects. Also, I read that you should avoid resizing a VBO (repeated calls to glBufferData with different size parameters), and instead choose a fixed size for a VBO, and just try a range from the buffer. I don't think changing the size of the buffer data would happen too often, but surely it would be better to only allocate the data you need? Choosing an arbitrary value seems risky. I'm looking for some advice on working with individual objects in a scene and their associated buffer data.

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• How should I interpret these DirectX Caps Viewer values?

  - by tobi

  Briefly asking - what do the nodes mean and what the difference is between them in DirectX Caps Viewer? DXGI Devices Direct3D9 Devices DirectDraw Devices The most interesting for me is 1 vs 2. In the Direct3D9 Devices under HAL node I can see that my GeForce 8800GT supports PixelShaderVersion 3.0. However, under DXGI Devices I have DX 10, DX 10.1 and DX 11 having Shader model 4.0 (actually why DX 11? My card is not compatible with DX 11). I am implementing a DX 11 application (including d3d11.h) with shaders compiled in 4.0 version, so I can clearly see that 4.0 is supported. What is the difference between 1 and 2? Could you give me some theory behind the nodes?

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• glsl demo suggestions ?

  - by brainydexter

  In a lot of places I interviewed recently, I have been asked many a times if I have worked with shaders. Even though, I have read and understand the pipeline, the answer to that question has been no. Recently, one of the places asked me if I can send them a sample of 'something' that is "visually polished". So, I decided to take the plunge and wrote some simple shader in GLSL(with opengl).I now have a basic setup where I can use vbos with glsl shaders. I have a very short window left to send something to them and I was wondering if someone with experience, could suggest an idea that is interesting enough to grab someone's attention. Thanks

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• How to modify VBO data

  - by Romeo

  I am learning LWJGL so i can start working on my game. In order to learn LWJGL I got the idea to implement the map builder so I can get comfortable with graphics programming. Now, for the map creation tool I need to draw new elements or draw the old one's with different coordinates. Let me explain this: My game will be a 2D scroller. The map will be consisting of multiple rectangles ( 2 strip triangles). When I click my left-mouse button i want to start the rectangle and when I release it I want to stop the rectangle bottom-right at that position. As I want to use VBOs I want to know how to modify data inside the VBO based on user input. Should i have a copy of a vertex array and then add the whole array to the VBO at each user input? How is usually implemented the VBO update?

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• What functionality should I use in OpenGL 2.0?

  - by Jeffrey

  Considering OpenGL 2.1, we all know that glBegin and glEnd are the devil. Should I use only VBO to render 3d primitives (I can't find VAO in that version, weren't there already?)? Should I still use the matrix stack (why not?)? Should I still use glFrustum? Can I take advantage of shaders in GLSL 1.20? Where can I find a tutorial for VBO in OpenGL 2.1 and the "correct" way of programming in it? Also how am I supposed to animate something. Like a cube moving around an object or a player moving in the scene (static vbo data + shader?)? Note: Take your time to answer this question, I'll accept an answer tomorrow.

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• 3D Texture Mapping (Atlas)

  - by Tim Hatch

  This is a pretty simple question. If I was to use multiple images in a single texture for a 3D cube, how would I go about re-using each vertex (having 8 total vs 24)? With a single buffer of 8 vertices, I don't see how I'd properly reuse the UV values. Any help on that? I know it's not terribly clear, but I figured it was a simple question. The 2D method is pretty easy, the next coordinates would be the same as the first (0,0 and 0,1 respectively). However, the above 3D version has me quite befuddled.

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• Need some help implementing VBO's with Frustum Culling

  - by Isracg

  i'm currently developing my first 3D game for a school project, the game world is completely inspired by minecraft (world completely made out of cubes). I'm currently seeking to improve the performance trying to implement vertex buffer objects but i'm stuck, i already have this methods implemented: Frustum culling, only drawing exposed faces and distance culling but i have the following doubts: I currently have about 2^24 cubes in my world, divided in 1024 chunks of 16*16*64 cubes, right now i'm doing immediate mode rendering, which works well with frustum culling, if i implement one VBO per chunk, do i have to update that VBO each time i move the camera (to update the frustum)? is there a performance hit with this? Can i dynamically change the size of each VBO? of do i have to make each one the biggest possible size (the chunk completely filled with objects)?. Would i have to keep each visited chunk in memory or could i efficiently remove that VBO and recreated it when needed?.

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• Implementing invisible bones

  - by DeadMG

  I suddenly have the feeling that I have absolutely no idea how to implement invisible objects/bones. Right now, I use hardware instancing to store the world matrix of every bone in a vertex buffer, and then send them all to the pipeline. But when dealing with frustrum culling, or having them set to invisible by my simulation for other reasons, means that some of them will be randomly invisible. Does this mean I effectively need to re-fill the buffer from scratch every frame with only the visible unit's matrices? This seems to me like it would involve a lot of wasted bandwidth.

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• How to acheive a smooth 2D lighting effect?

  - by Cyral

  I'm making a tile based game in XNA So currently my lightning looks like this: How can I get it to look like this? Instead of each block having its own tint, it has a smooth overlay. I'm assuming some sort of shader, and to tell it the lighting and blur it some how. But im not an expert with shaders. My current lighting calculates the light, and then passes it to a spritebatch and draws with a color parameter EDIT: No longer uses spritebatch tint, I was testing and now pass parameters to set the light values. But still looking for a way to smooth it

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