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The Computer Graphics site didn't have enough activity during the beta and has been closed. You can download the data dump of all questions here.

51 Example Questions

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up vote 23 down vote
What advantages does scanline rendering have over raytracer rendering?
added by Dan the Man Nov 14 '13 at 16:02
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Reminder: Each question needs only 10 upvotes. Beyond that, the votes are essentially wasted and could be better spent in some other question needing more votes. – Victor Stafusa Feb 12 '14 at 7:28
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@Victor Well said. – Dan the Man Feb 21 '14 at 17:32
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All the people who have already voted for this question are free to remove their vote so that they can vote for a worthy question which still needs to be brought up to 10. Provided this one doesn't drop below 10 it will still count towards the target. – githubphagocyte Mar 16 '14 at 11:45
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It's also worth taking a glance through to see the 5 questions you have upvoted. If they have exceeded 10 votes since you voted for them you can remove your vote and use it lower down. It's worth checking for this frequently as new votes keep coming in... – githubphagocyte Mar 20 '14 at 15:04
up vote 18 down vote
How can I improve the quality of my realtime shadows?
added by MickLH Nov 27 '13 at 20:56
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you must send the url for your code (in github) or at least say what are you doing (opengl or directX, using omni or other ligths, etc). – Pedro Polonia Feb 19 '14 at 0:48
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This site is still a proposal my friend! Perhaps I will start a community wiki with that if it passes! :) – MickLH Feb 21 '14 at 18:43
up vote 16 down vote
How are matrices used to represent and calculate 3d transformations?
added by Dan the Man Nov 18 '13 at 3:54
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up vote 16 down vote
Are there any advantages of using CPU over GPU for rendering?
added by CharlesL Nov 27 '13 at 19:51
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up vote 15 down vote
How to write a GLSL bloom pixel shader?
added by CharlesL Nov 18 '13 at 13:56
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up vote 14 down vote
How do you write a billboard shader in GLSL?
added by Dan the Man Nov 14 '13 at 16:00
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up vote 14 down vote
How efficient is Catmull-Clark subdivision surface on larger meshes (100k+ polygons)?
added by Dan the Man Nov 18 '13 at 4:45
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up vote 14 down vote
Why is it that conditional branches in GLSL shaders makes them so slow?
added by zedutchgandalf Nov 28 '13 at 10:49
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This isn't strictly true, but is only a trend in the current GPU hardware. The situation can be inverse on some completely viable rendering hardware. – MickLH Nov 30 '13 at 8:34
up vote 13 down vote
What is the difference between methodology used by direct3D and openGL for rendering?
added by noob Nov 28 '13 at 19:56
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up vote 11 down vote
Is this algorithm for creating a rhombic triacontahedron accurate?
added by Dan the Man Nov 14 '13 at 16:38
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up vote 10 down vote
Is it possible to add antialiasing to in image using ImageMagick?
added by CharlesL Nov 18 '13 at 17:30
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up vote 10 down vote
Are there any advantages for graphics cards that use shared memory?
added by zedutchgandalf Nov 28 '13 at 10:59
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up vote 10 down vote
What are the advantages of offline mipmap generation?
added by AbigailBuccaneer Nov 28 '13 at 11:58
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up vote 10 down vote
Is there any data structure tailored for storing in the GPU a scalar field for voxel rendering?
added by Trinidad Nov 28 '13 at 16:22
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Great question. – Dan the Man Nov 28 '13 at 18:54
up vote 10 down vote
What are the basics for porting a fixed function OpenGL 1.2 code to modern OpenGL?
added by Trinidad Nov 28 '13 at 16:23
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up vote 10 down vote
How can glossy reflections be implemented efficiently when using Image Based Lighting?
added by heishe Dec 14 '13 at 22:31
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Explanation: Glossy reflections aren't trivially implementable when using image-based light sources, because glossy reflections contain information from many different directions, and a simple texture lookup only samples one direction. Efficiently doing this is not trivial. Example answer would be to have a mip-map chain of the used IBL probe containing the different reflection values based on glossiness of the object, and then to interpolate between the different mip map levels somehow (perhaps just linear interpolation looks good enough). – heishe Jan 24 '14 at 23:04
Weighted average of the surrounding points in the lighting image, using a Gaussian distribution? A small enough sample over a wide enough area may be sufficient for a visually acceptable reflection. – githubphagocyte Mar 14 '14 at 22:23
up vote 10 down vote
What is the purpose of a "Z-prepass" and when should it be used?
added by heishe Dec 28 '13 at 21:05
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Explanation: z-prepass is a technique used to save fill-rate performance by drawing a depth-only rendering pass to populate the z-buffer. this (is supposed, at least,) to avoid the performance penalty from over-draw, for example when rendering the g-buffer pass in deferred shading or just normal rendering of meshes in forward-rendering. – heishe Jan 24 '14 at 23:07
up vote 10 down vote
When should you use the Graham scan algorithm instead of the Jarvis march algorithm for finding a convex hull?
added by Caleb Jan 21 '14 at 16:34
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up vote 10 down vote
Can the Navier-Stokes algorithm take full advantage of parallel processing with OpenCL?
added by Caleb Jan 21 '14 at 16:39
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up vote 10 down vote
Why do renderers essentially evaluate radiance seen for each pixel, as opposed to other physical quantities (radiant intensity, irradiance, etc.)?
added by heishe Jan 24 '14 at 23:10
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Looking for historical significance or algorithmic justification, to get a feel for the way things are done. Either way plenty of scope for citations and examples, and likely to give fresh insight for a large number of readers. – githubphagocyte Mar 13 '14 at 20:31
up vote 10 down vote
How can I realistically animate a sprite jumping? Right now, it looks like figure skating.
added by Brian Rushton Feb 5 '14 at 16:41
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I don't think this is a place for questions about animation and art related techniques. This is more about technical computer graphics programming and techniques. – Dan the Man Feb 21 '14 at 17:36
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Personally I would be happy to see animation questions if they concern the updating of an image and techniques to ensure consistency between frames - that seems nearer to the programming side of things. I agree that art questions are off topic - I wouldn't want to see "help! my animated cat looks more like a dog..." – githubphagocyte Mar 31 '14 at 20:31
up vote 10 down vote
Can finite subdivision rules be used to allow infinite scaling of flat polygonal meshes?
added by Brian Rushton Feb 5 '14 at 16:42
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up vote 10 down vote
Are there efficient algorithms for estimating the homology of black-on white figures?
added by Brian Rushton Feb 5 '14 at 16:46
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up vote 10 down vote
What is the state of art in screen space sampling techniques for Monte Carlo rendering?
added by apiad Feb 19 '14 at 16:11
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Explanation: In classic Monte Carlo rendering algorithms (Path Tracing, MLT, Bidirectional PT), a fixed number of rays is shoot through each pixel. All optimizations are done in the object space (importance sampling, etc.), i.e, for rays that belong to the same pixel. However, we could also optimize in the screen space, spending less rays in "easier" pixels (which converge faster) and more rays in more problematic areas (such as caustics). This question is about exposing existing techniques for determining the optimal number of rays to dedicate to each pixel, to maximize overall image quality. – apiad Feb 19 '14 at 16:16
This is the kind of question I would really like to see. If there's anyone who doesn't consider it worthy of an upvote I'd be fascinated to know why. – githubphagocyte Mar 13 '14 at 20:29
up vote 10 down vote
This caustic algorithm renders twice as fast as anything else, which makes me cautious. How could I exhaustively test it with concave models?
added by githubphagocyte Mar 13 '14 at 20:12
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up vote 10 down vote
I'm aiming to use GPGPU parallel processing distributed across 6 computers (my 2 plus 4 friends over the internet). Can I mix GPU-X and GPU-Y?
added by githubphagocyte Mar 13 '14 at 20:19
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up vote 10 down vote
I'm looking to render a scene over a 4x4 array of monitors, so the resolution is higher than my GPU can handle. Can I somehow get a partial speed up?
added by githubphagocyte Mar 13 '14 at 20:23
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up vote 10 down vote
I'm learning Python so I wrote a raytracer. All my reflections come out in green, even though everything else looks fine.
added by githubphagocyte Mar 13 '14 at 20:26
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up vote 10 down vote
In ray tracing, why are transforms usually applied in reverse on rays instead of normally on the objects?
added by System Down Mar 18 '14 at 18:37
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up vote 10 down vote
How would you simulate a lens in ray tracing?
added by System Down Mar 18 '14 at 18:52
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up vote 10 down vote
How is smoke simulated in ray tracing?
added by System Down Mar 18 '14 at 18:52
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up vote 10 down vote
How could I write a cel shader in GLSL?
added by zedutchgandalf Mar 18 '14 at 23:23
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up vote 10 down vote
Is there a variation of the Bresenham algorithm for drawing an ellipse on the plane with axes not parallel to coordinate axes?
added by Gassa Mar 20 '14 at 14:53
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up vote 10 down vote
Why is a fast inverse square root so important in 3D graphics?
added by System Down Apr 5 '14 at 5:32
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up vote 10 down vote
How can I write a YUV420p to RGB shader in GLSL?
added by cloudraven Apr 6 '14 at 6:30
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up vote 9 down vote
What are the required properties of a material used in physically based rendering?
added by Mokosha Nov 28 '13 at 15:15
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up vote 9 down vote
What are the common principles behind physically based rendering?
added by heishe Dec 1 '13 at 10:11
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up vote 9 down vote
Why does performing the perspective divide in a vertex shader cause artifacts to appear?
added by Mokosha Dec 9 '13 at 0:06
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up vote 9 down vote
Is quaternion mathematics still relevant in modern 3D programming?
added by cww Dec 17 '13 at 10:45
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up vote 9 down vote
How is efficient tree traversal (e.g. for ray tracing) implemented in shaders?
added by heishe Dec 28 '13 at 21:12
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Explanation: Traversing a tree (such as an octree) in shaders can be problematic, due to traversal usually including many branches [bad on many graphics hardware architectures] and shaders having no stack available can cause problems also. – heishe Dec 28 '13 at 21:15
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