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• Big problem with Dijkstra algorithm in a linked list graph implementation

  - by Nazgulled

  Hi, I have my graph implemented with linked lists, for both vertices and edges and that is becoming an issue for the Dijkstra algorithm. As I said on a previous question, I'm converting this code that uses an adjacency matrix to work with my graph implementation. The problem is that when I find the minimum value I get an array index. This index would have match the vertex index if the graph vertexes were stored in an array instead. And the access to the vertex would be constant. I don't have time to change my graph implementation, but I do have an hash table, indexed by a unique number (but one that does not start at 0, it's like 100090000) which is the problem I'm having. Whenever I need, I use the modulo operator to get a number between 0 and the total number of vertices. This works fine for when I need an array index from the number, but when I need the number from the array index (to access the calculated minimum distance vertex in constant time), not so much. I tried to search for how to inverse the modulo operation, like, 100090000 mod 18000 = 10000 and, 10000 invmod 18000 = 100090000 but couldn't find a way to do it. My next alternative is to build some sort of reference array where, in the example above, arr[10000] = 100090000. That would fix the problem, but would require to loop the whole graph one more time. Do I have any better/easier solution with my current graph implementation?

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• Draw LINE_STRIP with Unity

  - by Boozzz

  For a new project I am thinking about whether to use OpenGL or Unity3d. I have a bit of experience with OpenGL, but I am completely new to Unity. I already read through the Unity documentation and tutorials on the Unity Website. However, I could not find a way to draw a simple Line-Strip with Unity. In the following example (C#, OpenGL/SharpGL) I draw a round trajectory from a predifined point to an obstacle, which can be imagined as a divided circle with midpoint [cx,cy] and radius r. The position (x-y coordinates) of the obstacle is given by obst_x and obst_y. Question 1: How could I do the same with Unity? Question 2: In my new project, I will have to draw quite a lot of such geometric primitives. Does it make any sense to use Unity for those things? void drawCircle(float cx, float cy, float r, const float obst_x, const float obst_y) { float theta = 0.0f, pos_x, pos_y, dist; const float delta = 0.1; glBegin(GL_LINE_STRIP); while (theta < 180) { theta += delta; //get the current angle float x = r * cosf(theta); //calculate the x component float y = r * sinf(theta); //calculate the y component pos_x = x + cx; //calculate current x position pos_y = y + cy; //calculate current y position //calculate distance from current vertex to obstacle dist = sqrt(pow(pos_x - obst_x) + pow(pos_y - obst_y)); //check if current vertex intersects with obstacle if dist <= 0 { break; //stop drawing circle } else { glVertex2f(pos_x, pos_y); //draw vertex } } glEnd(); }

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• Proving that the distance values extracted in Dijkstra's algorithm is non-decreasing?

  - by Gail

  I'm reviewing my old algorithms notes and have come across this proof. It was from an assignment I had and I got it correct, but I feel that the proof certainly lacks. The question is to prove that the distance values taken from the priority queue in Dijkstra's algorithm is a non-decreasing sequence. My proof goes as follows: Proof by contradiction. Fist, assume that we pull a vertex from Q with d-value 'i'. Next time, we pull a vertex with d-value 'j'. When we pulled i, we have finalised our d-value and computed the shortest-path from the start vertex, s, to i. Since we have positive edge weights, it is impossible for our d-values to shrink as we add vertices to our path. If after pulling i from Q, we pull j with a smaller d-value, we may not have a shortest path to i, since we may be able to reach i through j. However, we have already computed the shortest path to i. We did not check a possible path. We no longer have a guaranteed path. Contradiction.

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• Suggestions of the easiest algorithms for some Graph operations

  - by Nazgulled

  Hi, The deadline for this project is closing in very quickly and I don't have much time to deal with what it's left. So, instead of looking for the best (and probably more complicated/time consuming) algorithms, I'm looking for the easiest algorithms to implement a few operations on a Graph structure. The operations I'll need to do is as follows: List all users in the graph network given a distance X List all users in the graph network given a distance X and the type of relation Calculate the shortest path between 2 users on the graph network given a type of relation Calculate the maximum distance between 2 users on the graph network Calculate the most distant connected users on the graph network A few notes about my Graph implementation: The edge node has 2 properties, one is of type char and another int. They represent the type of relation and weight, respectively. The Graph is implemented with linked lists, for both the vertices and edges. I mean, each vertex points to the next one and each vertex also points to the head of a different linked list, the edges for that specific vertex. What I know about what I need to do: I don't know if this is the easiest as I said above, but for the shortest path between 2 users, I believe the Dijkstra algorithm is what people seem to recommend pretty often so I think I'm going with that. I've been searching and searching and I'm finding it hard to implement this algorithm, does anyone know of any tutorial or something easy to understand so I can implement this algorithm myself? If possible, with C source code examples, it would help a lot. I see many examples with math notations but that just confuses me even more. Do you think it would help if I "converted" the graph to an adjacency matrix to represent the links weight and relation type? Would it be easier to perform the algorithm on that instead of the linked lists? I could easily implement a function to do that conversion when needed. I'm saying this because I got the feeling it would be easier after reading a couple of pages about the subject, but I could be wrong. I don't have any ideas about the other 4 operations, suggestions?

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• own drawImage / drawLine in OpenGL

  - by Chrise

  I'm implementing some native 2D-draw functions in my graphics engine for android, but now there's another question coming up, when I observe the performance of my program. At the moment I'm implementing a drawLine/drawImage function. In summary, there are following different values for drawing each different line / image: the color the alpha value the width of the line rotation (only for images) size/scale (also for images) blending method (subrtract, add, normal-alpha) Now, when an imageLine is drawn, I put the CPU-calculated vertex-positions and uv-values for 6 vertices (2 triangles), into a Floatbuffer and draw it immediately with drawArrays, after passing information for drawing (color,alpha, etc.) via uniforms to the shader. When I draw an image, the pre-set VBO is directly drawn after passing information. The first fact I recognized, is: of course drawing Images is much faster, than imagelines (beacuse of VBOs), but also: I cannot pre-put vertex-data into a VBO for imageLines, because imageLines have no static shape like normal images (varying linelength, varying linewidth and the vertex positions of x1,y1 and x2,y2 change too often) That's why I use a normal Floatbuffer, instead of a VBO. So my question is: What's the best way for managing images, and other 2D-graphics functions. For me it's some kind of important, that the user of the engine is able to draw as many images/2D graphics as possible, without loosing to much performance. You can find the functions for drawing images, imagelines, rects, quads, etc. here: https://github.com/Chrise55/LLama3D/blob/master/Llama3DLibrary/src/com/llama3d/object/graphics/image/ImageBase.java Here an example how it looks with many images (testing artificial neural networks), it works fine, but already little bit slow with that many images... :(

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• Cloning ID3DXMesh with declration that has 12 floats breaks?

  - by meds

  I have the following vertex declration: struct MESHVERTInstanced { float x, y, z; // Position float nx, ny, nz; // Normal float tu, tv; // Texcoord float idx; // index of the vertex! float tanx, tany, tanz; // The tangent const static D3DVERTEXELEMENT9 Decl[6]; static IDirect3DVertexDeclaration9* meshvertinstdecl; }; And I declare it as such: const D3DVERTEXELEMENT9 MESHVERTInstanced::Decl[] = { { 0, 0, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0 }, { 0, 12, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_NORMAL, 0 }, { 0, 24, D3DDECLTYPE_FLOAT2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD, 0 }, { 0, 32, D3DDECLTYPE_FLOAT1, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD, 1 }, { 0, 36, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TANGENT, 0 }, D3DDECL_END() }; What I try to do next is copy an ID3DXMesh into another one with the new vertex declaration as such: model->CloneMesh( model->GetOptions(), MESHVERTInstanced::Decl, gd3dDevice, &pTempMesh ); When I try to get the FVF size of pTempMesh (D3DXGetFVFVertexSize(pTempMesh-GetFVF())) I get '0' though the size should be 48. The whole thing is fine if I don't have the last declaration, '{ 0, 36, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TANGENT, 0 },' in it and the CloneMesh function does not return a FAIL. I've also tried using different declarations such as D3DDECLUSAGE_TEXCOORD and that has worked fine, returning a size of 48. Is there something specific about D3DDECLUSAGE_TANGENT I don't know? I'm at a complete loss as to why this isn't working...

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• Java: Inputting text from a file using split

  - by 00PS

  I am inputting an adjacency list for a graph. There are three columns of data (vertex, destination, edge) separated by a single space. Here is my implementation so far: FileStream in = new FileStream("input1.txt"); Scanner s = new Scanner(in); String buffer; String [] line = null; while (s.hasNext()) { buffer = s.nextLine(); line = buffer.split("\\s+"); g.add(line[0]); System.out.println("Added vertex " + line[0] + "."); g.addEdge(line[0], line[1], Integer.parseInt(line[2])); System.out.println("Added edge from " + line[0] + " to " + line[1] + " with a weight of " + Integer.parseInt(line[2]) + "."); } System.out.println("Size of graph = " + g.size()); Here is the output: Added vertex a. Added edge from a to b with a weight of 9. Exception in thread "main" java.lang.NullPointerException at structure5.GraphListDirected.addEdge(GraphListDirected.java:93) at Driver.main(Driver.java:28) I was under the impression that line = buffer.split("\\s+"); would return a 2 dimensional array of Strings to the variable line. It seemed to work the first time but not the second. Any thoughts? I would also like some feedback on my implementation of this problem. Is there a better way? Anything to help out a novice! :)

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• Overlay an image over video using OpenGL ES shaders

  - by BlueVoodoo

  I am trying to understand the basic concepts of OpenGL. A week into it, I am still far from there. Once I am in glsl, I know what to do but I find getting there is the tricky bit. I am currently able to pass in video pixels which I manipulate and present. I have then been trying to add still image as an overlay. This is where I get lost. My end goal is to end up in the same fragment shader with pixel data from both my video and my still image. I imagine this means I need two textures and pass on two pixel buffers. I am currently passing the video pixels like this: glGenTextures(1, &textures[0]); //target, texture glBindTexture(GL_TEXTURE_2D, textures[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_BYTE, buffer); Would I then repeat this process on textures[1] with the second buffer from the image? If so, do I then bind both GL_TEXTURE0 and GL_TEXTURE1? ...and would my shader look something like this? uniform sampler2D videoData; uniform sampler2D imageData; once I am in the shader? It seems no matter what combination I try, image and video always ends up being just video data in both these. Sorry for the many questions merged in here, just want to clear my many assumptions and move on. To clarify the question a bit, what do I need to do to add pixels from a still image in the process described? ("easy to understand" sample code or any types of hints would be appreciated).

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• Change value of adjacent vertices and remove self loop

  - by StereoMatching

  Try to write a Karger’s algorithm with boost::graph example (first column is vertice, other are adjacent vertices): 1 2 3 2 1 3 4 3 1 2 4 4 2 3 assume I merge 2 to 1, I get the result 1 2 3 2 1 1 3 4 2 1 3 4 3 1 2 4 4 2 3 first question : How could I change the adjacent vertices("2" to "1") of vertice 1? my naive solution template<typename Vertex, typename Graph> void change_adjacent_vertices_value(Vertex input, Vertex value, Graph &g) { for (auto it = boost::adjacent_vertices(input, g); it.first != it.second; ++it.first){ if(*it.first == value){ *(it.first) = input; //error C2106: '=' : left operand must be l-value } } } Apparently, I can't set the value of the adjacent vertices to "1" by this way The result I want after "change_adjacent_vertices_value" 1 1 3 1 1 1 3 4 2 1 3 4 3 1 2 4 4 2 3 second question : How could I pop out the adjacent vertices? Assume I want to pop out the consecutive 1 from the vertice 1 The result I expected 1 1 3 1 3 4 2 1 3 4 3 1 2 4 4 2 3 any function like "pop_adjacent_vertex" could use?

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• Unity stuck in 2D mode, Nvidia Quadro graphics "unknown", Nvidia-Current active but not in use

  - by Jordan Lund

  I've seen this problem reported under several questions, but I haven't been able to resolve any of it so I thought I'd bring it all in under one umbrella. I started a new job and was given a Dell Precision M6400 laptop with Nvidia Quadro FX 2700M graphics card. It had a previous version of Ubuntu on it, but nobody had any passwords for it so I wiped the drive and did a fresh install of 11.10 from scratch. I didn't do any updates during installation, preferring to do them after boot. Updates ran fine and the system works... except Unity is in 2D mode. System Settings - Additional Drivers shows that Nvidia-Current is active but not in use. System Settings - System Info shows Graphics Driver Unknown, Experience Standard Nvidia X Server Settings is installed and working, re-writing the xorg.conf did nothing. /usr/lib/nux/unity_support_test -p OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: Quadro FX 2700M/PCI/SSE2 OpenGL version string: 3.3.0 NVIDIA 285.05.09 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: yes One suggestion was to do a sudo apt-get --purge remove nvidia* and that resulted in a scrambled screen on boot and a non-bootable installation. Pressing the Delete key on boot allowed me to access the recovery console and do a sudo apt-get install nvidia-current, which brought me back to a working, bootable system. Another suggestion was to edit /etc/default/grub and change the line reading "GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to read "GRUB_CMDLINE_LINUX_DEFAULT="quiet splash vmalloc=192MB" thus allocating more video RAM. I did that, followed by a sudo update-grub and a re-boot. No change. Created a brand new standard user and logged on with that account, no change.

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• How to gain accurate results with Painter's algorithm?

  - by pimvdb

  A while ago I asked how to determine when a face is overlapping another. The advice was to use a Z-buffer. However, I cannot use a Z-buffer in my current project and hence I would like to use the Painter's algorithm. I have no good clue as to when a surface is behind or in front of another, though. I've tried numerous methods but they all fail in edge cases, or they fail even in general cases. This is a list of sorting methods I've tried so far: Distance to midpoint of each face Average distance to each vertex of each face Average z value of each vertex Higest z value of vertices of each face and draw those first Lowest z value of vertices of each face and draw those last The problem is that a face might have a closer distance but is still further away. All these methods seem unreliable. Edit: For example, in the following image the surface with the blue point as midpoint is painted over the surface with the red point as midpoint, because the blue point is closer. However, this is because the surface of the red point is larger and the midpoint is further away. The surface with the red point should be painted over the blue one, because it is closer, whilst the midpoint distance says the opposite. What exactly is used in the Painter's algorithm to determine the order in which objects should be drawn?

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• OpenGL ES 2 shaders for drawing buildings and roads like Google Maps does

  - by Pris

  I'm trying to create a shader that'll give me an effect similar to what buildings and roads look like on 3D Google Maps. You can see the effect interactively if you enable WebGL at maps.google.com, and I also found a couple of screenshots that illustrate what I'm trying to achieve: Thing I noticed: There's some kind of transparency thing going on with the roads/ground and the buildings, but not between the buildings themselves. It might be that they're rendering the ground and roads after the buildings with the right blend functions to achieve that effect. If you look closely, you'll see parts of the building profiles have an outline. The roads also have nice clean outlines. There are a lot of techniques for outlining things with shaders... but I'm curious to find out what might have been used in this case considering mobile hardware and a large number of entities with outlines (roads and buildings) I'm assuming that for the lighting, some sort of simple diffuse per-vertex shader is being used for the buildings though I could be wrong. I'm especially curious about the 'look' they achieved with buildings (clean, precise outlines/shading). It reminds me a little of what you'd see when designing stuff with CAD applications like SolidWorks: I'd appreciate any advice on achieving this kind of look with ES 2 shaders.

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• Use depth bias for shadows in deferred shading

  - by cubrman

  We are building a deferred shading engine and we have a problem with shadows. To add shadows we use two maps: the first one stores the depth of the scene captured by the player's camera and the second one stores the depth of the scene captured by the light's camera. We then ran a shader that analyzes the two maps and outputs the third one with the ready shadow areas for the current frame. The problem we face is a classic one: Self-Shadowing: A standard way to solve this is to use the slope-scale depth bias and depth offsets, however as we are doing things in a deferred way we cannot employ this algorithm. Any attempts to set depth bias when capturing light's view depth produced no or unsatisfying results. So here is my question: MSDN article has a convoluted explanation of the slope-scale: bias = (m × SlopeScaleDepthBias) + DepthBias Where m is the maximum depth slope of the triangle being rendered, defined as: m = max( abs(delta z / delta x), abs(delta z / delta y) ) Could you explain how I can implement this algorithm manually in a shader? Maybe there are better ways to fix this problem for deferred shadows?

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• Writing the correct value in the depth buffer when using ray-casting

  - by hidayat

  I am doing a ray-casting in a 3d texture until I hit a correct value. I am doing the ray-casting in a cube and the cube corners are already in world coordinates so I don't have to multiply the vertices with the modelviewmatrix to get the correct position. Vertex shader world_coordinate_ = gl_Vertex; Fragment shader vec3 direction = (world_coordinate_.xyz - cameraPosition_); direction = normalize(direction); for (float k = 0.0; k < steps; k += 1.0) { .... pos += direction*delta_step; float thisLum = texture3D(texture3_, pos).r; if(thisLum > surface_) ... } Everything works as expected, what I now want is to sample the correct value to the depth buffer. The value that is now written to the depth buffer is the cube coordinate. But I want the value of pos in the 3d texture to be written. So lets say the cube is placed 10 away from origin in -z and the size is 10*10*10. My solution that does not work correctly is this: pos *= 10; pos.z += 10; pos.z *= -1; vec4 depth_vec = gl_ProjectionMatrix * vec4(pos.xyz, 1.0); float depth = ((depth_vec.z / depth_vec.w) + 1.0) * 0.5; gl_FragDepth = depth;

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• Screen becomes black after pressing dash or alt-tab

  - by cegerxwin

  I did an upgrade from 11.04 to 11.10. Unity 3d becomes a black screen after pressing the dash-button or after pressing alt-tab to switch between open windows. I can see the panel on the top(lock,sound,..) and the panel on the left (launcher) but the rest is black. It looks like a maximised black window. The open Windows are active but I cant see them. I logout by pressing logout in the right top corner and pressing enter (because logout is default focused on the dialogue screen) and leave unity3d. Unity3d worked with 11.04 very good. If I press the dash button the dash looks like an 16-Bit or 8-Bit window and buttons for maximise, minimise and close are displayed and looks inverted. I have rebooted my notebook just now and log in to Unity 3D and tested some features of Unity and everything works well. The black thing is only a layer. I can use my desktop but cant see anything because of the layer, but everything works. It seems so, that a layer appear when pressing dash or alt-tab and does not disappear when close dash or choose a running app with alt-tab. you will see the necessary info related video problems: Unity support: /usr/lib/nux/unity_support_test -p OpenGL vendor string: X.Org R300 Project OpenGL renderer string: Gallium 0.4 on ATI RC410 OpenGL version string: 2.1 Mesa 7.11-devel Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: yes xorg glxinfo lspci -nn | grep VGA 01:05.0 VGA compatible controller [0300]: ATI Technologies Inc RC410 [Radeon Xpress 200M] [1002:5a62]

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• Cocos2d: Tongue effect like in Munch Time

  - by Joey Green

  I'm wanting to do a tongue effect for my character like the one in Munch Time( shown in pic ). The player does some action and his tongue attaches to the nearest platform. I'm thinking this is simply a get distance to platform and keep player at that distance as he moves back and forth giving him the swinging effect. For the drawing, I'm wanting the same effect where the tongue sprite is the skinniest in the middle of the distance between the character and platform. I know how to do this in a shader( I'm using cocos2d v2 btw ), but I'm wondering if there is some built-in functionality to allow me to do this. First, is this the right approach using distance? Second, is their an easy way to do the tongue sprite effect without a shader? Third, I'm wanting to have the player spring up at will in the direction of the platform. I'm using Box2D. Would there be a way to do this using force's or would it be easier to write my own code?

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• BlitzMax - generating 2D neon glowing line effect to png file

  - by zanlok

  Originally asked on StackOverflow, but it became tumbleweed. I'm looking to create a glowing line effect in BlitzMax, something like a Star Wars lightsaber or laserbeam. Doesn't have to be realtime, but just to TImage objects and then maybe saved to PNG for later use in animation. I'm happy to use 3D features, but it will be for use in a 2D game. Since it will be on black/space background, my strategy is to draw a series of white blurred lines with color and high transparency, then eventually central lines less blurred and more white. What I want to draw is actually bezier curved lines. Drawing curved lines is easy enough, but I can't use the technique above to create a good laser/neon effect because it comes out looking very segmented. So, I think it may be better to use a blur effect/shader on what does render well, which is a 1-pixel bezier curve. The problems I've been having are: Applying a shader to just a certain area of the screen where lines are drawn. If there's a way to do draw lines to a texture and then blur that texture and save the png, that would be great to hear about. There's got to be a way to do this, but I just haven't gotten the right elements working together yet. Any help from someone familiar with this stuff would be greatly appreciated. Using just 2D calls could be advantageous, simpler to understand and re-use. It would be very nice to know how to save a PNG that preserves the transparency/alpha stuff. p.s. I've reviewed this post (and many many others on the Blitz site), have samples working, and even developed my own 5x5 frag shaders. But, it's 3D and a scene-wide thing that doesn't seem to convert to 2D or just a certain area very well. I'd rather understand how to apply shading to a 2D scene, especially using the specifics of BlitzMax.

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• How to enable Unity 3D support in 12.04 using open-source drivers for RadeonHD cards?

  - by martin

  As the title says I can't enable the Unity 3D support when I'm using open-source drivers (xorg-edgers). I have an xfx Radeon HD 6950 by the way. If I install the proprietary 12.3 drivers from AMD it works, but I get poorer 2D performance than the open-source drivers and also I get some freezes and lock ups at random. So because of this I'm trying the open-source drivers and so far no issues at all, except this one. Running this command $ /usr/lib/nux/unity_support_test -p shows this: OpenGL vendor string: VMware, Inc. OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 0x300) OpenGL version string: 2.1 Mesa 8.0.2 Not software rendered: no Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: no And this command $ lspci -nn | grep VGA shows: 01:00.0 VGA compatible controller [0300]: Advanced Micro Devices [AMD] nee ATI Cayman PRO [Radeon HD 6950] [1002:6719] So, is this normal? Do I need to go back to proprietary drivers to enable Unity 3D? If anyone can give me help, I'll much appreciate it.

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• Billboarding restricted to an axis (cylindrical)

  - by user8709

  I have succesfully created a GLSL shader for a billboarding effect. I want to tweak this to restrict the billboarding to an arbitrary axis, i.e. a billboarded quad only rotates itself about the y-axis. I use the y-axis as an example, but essentially I would like this to be an arbitrary axis. Can anyone show me how to modify my existing shader below, or if I need to start from scratch, point me towards some resources that could be helpful? precision mediump float; uniform mat4 u_modelViewProjectionMat; uniform mat4 u_modelMat; uniform mat4 u_viewTransposeMat; uniform vec3 u_axis; // <------------ !!! the arbitrary axis to restrict rotation around attribute vec3 a_position0; attribute vec2 a_texCoord0; varying vec2 v_texCoord0; void main() { vec3 pos = (a_position0.x * u_viewTransposeMat[0] + a_position0.y * u_viewTransposeMat[1]).xyz; vec4 position = vec4(pos, 1.0); v_texCoord0 = a_texCoord0; gl_Position = u_modelViewProjectionMat * position; }

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• Stage3D: Camera pans the whole screen

  - by Thomas Versteeg

  I am trying to create a 2D Stage3D game where you can move the camera around the level in an RTS style. I thought about using Orthographic Matrix3D functions for this but when I try to scroll the whole "stage" also scrolls. This is the Camera code: public function Camera2D(width:int, height:int, zoom:Number = 1) { resize(width, height); _zoom = zoom; } public function resize(width:Number, height:Number):void { _width = width; _height = height; _projectionMatrix = makeMatrix(0, width, 0, height); _recalculate = true; } protected function makeMatrix(left:Number, right:Number, top:Number, bottom:Number, zNear:Number = 0, zFar:Number = 1):Matrix3D { return new Matrix3D(Vector.<Number>([ 2 / (right - left), 0, 0, 0, 0, 2 / (top - bottom), 0, 0, 0, 0, 1 / (zFar - zNear), 0, 0, 0, zNear / (zNear - zFar), 1 ])); } public function get viewMatrix():Matrix3D { if (_recalculate) { _recalculate = false; _viewMatrix.identity(); _viewMatrix.appendTranslation( -_width / 2 - _x, -_height / 2 - y, 0); _viewMatrix.appendScale(_zoom, _zoom, 1); _renderMatrix.identity(); _renderMatrix.append(_viewMatrix); _renderMatrix.append(_projectionMatrix); } return _renderMatrix; } And the camera is send directly to the GPU with: c3d.setProgramConstantsFromMatrix(Context3DProgramType.VERTEX, 0, cameraMatrix, true); And these are the shaders: ------Vertex Shader------ m44 op, va0, vc0 mov v0, va1.xy mov v0.z, va0.z ------Fragment Shader------ tex ft0, v0, fs0 <2d,linear,nomip> mov oc, ft1 Here is a example and here are two screenshots to show what I mean: How do I only let the inside of the stage3D scroll and not the whole stage?

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• Tessellating to a curve?

  - by Avi

  I'm creating a game engine, and I'm trying to define a 3D model format I want to use. I haven't come across a format that quite does what I want. My game engine assumes a shader model 5+ environment. By the time I'm finished with it, that won't be a very unreasonable requirement. Because it assumes such a modern environment, I'm going to try and exploit tessellation. The most popular way, it seems, to procedurally increase geometry through tessellation is to tessellate to a height map. This works for a lot of things, but has limitations in that height maps still use up VRAM and also only have finite scalability. So I want to be able to use curves to define what a mesh should tessellate to. The thing is, I have no idea what definition of curves I should use, how I should store it, and how I should tessellate to it. Do I use NURBS curves? Bezier? Hermite? And once I figure that out, is there an algorithm to determine how the tessellation shader should produce and move vertices to match the curve as closely as possible? Is the infinite scalability and lower memory usage when compared to height maps worth the added computational complexity? I'm sorry I'm kind if ignorant as to these matters. I just don't know where to start.

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• Is there a way to display navmesh agent path in Unity?

  - by Antoine Guillien

  I'm currently making a prototype for a game I plan to develop. As far as I did, I managed to set up the navigation mesh and my navmeshagents. I would like to display the path they are following when setDestination() is fired. I did some researches but didn't find anything about it. EDIT 1 : So I instantiate an empty object with a LineRenderer and I have a line bewteen my agent and the destination. Still I've not all the points when the path has to avoid an obstacle. Furthermore, I wonder if the agent.path does reflect the real path that the agent take as I noticed that it actually follow a "smoothier" path. Here is the code so far : GameObject container = new GameObject(); container.transform.parent = agent.gameObject.transform; LineRenderer ligne = container.AddComponent<LineRenderer>(); ligne.SetColors(Color.white,Color.white); ligne.SetWidth(0.1f,0.1f); //Get def material ligne.gameObject.renderer.material.color = Color.white; ligne.gameObject.renderer.material.shader = Shader.Find("Sprites/Default"); ligne.gameObject.AddComponent<LineScript>(); ligne.SetVertexCount(agent.path.corners.Length+1); int i = 0; foreach(Vector3 v in p.corners) { ligne.SetPosition(i,v); //Debug.Log("position agent"+g.transform.position); //Debug.Log("position corner = "+v); i++; } ligne.SetPosition(p.corners.Length,agent.destination); ligne.gameObject.tag = "ligne"; So How can I get the real coordinates my agent is going to walk throught ?

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• Ubuntu and bumblebee and intel problem

  - by LnxSlck

  I have a brain teaser that i can't solve. When 12.04 (64bits) came out, i did a fresh install and then installed bumblebee with: sudo add-apt-repository ppa:bumblebee/stable sudo apt-get install bumblebee bumblebee-nvidia And Ubuntu recognized (System Settings - Details) Intel Card for primary card, and i could launch applications with optirun. I have: 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 01:00.0 VGA compatible controller: NVIDIA Corporation GF119 [GeForce GT 520MX] (rev ff) Now, a few days back, i did the exact same thing, installed from the same DVD everything the same, installed bumblebee the same way. Nvidia with Optirun works fine, but Ubuntu doesn't have 3D effects: root@deathstar:~# optirun /usr/lib/nux/unity_support_test -p OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: GeForce GT 520MX/PCIe/SSE2 OpenGL version string: 4.2.0 NVIDIA 295.40 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: no GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: no I never did anything to install Intel drivers (except installing mesa-utils), before bumblebee got everything working, but now i can't get Ubuntu to get Unity with 3D. Can someone help me please get Unity 3d working? Your help will be much appreciated

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• nvidia segfault crashes XServer (12.04 fresh install)

  - by Sébastien GILLES

  I am on a fresh install of 12.04, and my video card is a Quadro FX 570, which appears to be supported (see output of unity_support_test below). But my Xserver crashes randomly and causes my session to just shutdown and bring me back to the logging screen. This happens several times per hour. After checking syslog it that a segfault in the nvidia driver is the cause of the problem: Jun 13 11:14:17 lima kernel: [86569.828982] Xorg[17940]: segfault at ffebeb69 ip b4c8f7aa sp bf8076dc error 4 in nvidia_drv.so[b47a7000+706000] Jun 13 11:14:36 lima gnome-session[18119]: Gdk-WARNING: gnome-session: Fatal IO error 11 (Ressource temporairement non disponible) on X server :3.#012 The funny thing is that as I was reporting this bug, my xserver crashed again (!) and this time I got another error message: Jun 13 11:29:39 lima kernel: [87491.106441] NVRM: Xid (0000:02:00): 6, PE0001 Jun 13 11:29:39 lima gnome-session[26493]: Gdk-WARNING: gnome-session: Fatal IO error 11 (Ressource temporairement non disponible) on X server :4.#012 Any idea as to what can be the problem given that i am on a fresh install with a supported video card ? Sébastien == Output of unity_support_test $ /usr/lib/nux/unity_support_test -p OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: Quadro FX 570/PCIe/SSE2 OpenGL version string: 3.3.0 NVIDIA 295.40 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: yes

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• Creating a retro-style palette swapping effect in OpenGL

  - by Zack The Human

  I'm working on a Megaman-like game where I need to change the color of certain pixels at runtime. For reference: in Megaman when you change your selected weapon then main character's palette changes to reflect the selected weapon. Not all of the sprite's colors change, only certain ones do. This kind of effect was common and quite easy to do on the NES since the programmer had access to the palette and the logical mapping between pixels and palette indices. On modern hardware, though, this is a bit more challenging because the concept of palettes is not the same. All of my textures are 32-bit and do not use palettes. There are two ways I know of to achieve the effect I want, but I'm curious if there are better ways to achieve this effect easily. The two options I know of are: Use a shader and write some GLSL to perform the "palette swapping" behavior. If shaders are not available (say, because the graphics card doesn't support them) then it is possible to clone the "original" textures and generate different versions with the color changes pre-applied. Ideally I would like to use a shader since it seems straightforward and requires little additional work opposed to the duplicated-texture method. I worry that duplicating textures just to change a color in them is wasting VRAM -- should I not worry about that?

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