All Questions

-1
votes
0answers
21 views

Insert an edges in a surface - CGAL error: assertion violation

'm creating an application using qt creator which read .off files as CGAL::Linear_cell_complex_for_combinatorial_map and preview it I want to make operations on the read mesh such as removing edge and ...
-1
votes
2answers
83 views

How to use multisampling with “if … return” in a fragment shader?

I draw transparent figures by depth peeling, the result is ugly when I render to multisample (a grid appears) ...
2
votes
0answers
29 views

Transforming arcs and perspective change

I have a SVG with group of independent arcs that move around common origin. On user event those arcs can change both their radii and start/end angles. On other user event the user can change view from ...
-1
votes
0answers
19 views

Compose multiple images in a single SDL surface

In this piece of code i managed to load a image with SDL and then succesfully pass it as a texture. Basically ...
2
votes
1answer
73 views

Computing sRGB color from SPDs

I'm trying to write my own spectral path tracer and a bit stuck with converting computed SPDs to LDR RGB values. What I'm doing right now is convert sampled SPDs (in ...
0
votes
1answer
42 views

Inconsistent behavior involving VkPhysicalDeviceFeatures.fillModeNonSolid

I departed slightly from the Vulkan tutorial I was following and decided to draw a wireframe instead of a solid triangle. As soon as I call ...
4
votes
1answer
51 views

Modify camera matrix so that it renders a “chunk” of the frustum

Given a perspective projection matrix. How can one from it derive a set of matrices representing "chunks" of the viewport? So that the rendered chunks can be "stiched" to form an image "chunk times ...
1
vote
1answer
42 views

Confused on reflection coeffcient of Fresnel equations

I am reading a paper about layered materials. However, I am confused on the implementation of this paper. The following picture describe the layered material. r_ab is a complex reflection coeffcient ...
2
votes
1answer
57 views

Bump mapping with triangles and height maps

I'm trying to add bump mapping to my ray tracer, and I'm currently struggling to add bump mapping to it, as I don't seem to get the transformations from texture space to world space correctly. I have ...
0
votes
1answer
50 views

Efficiently drawing multiple instances of 3D objects

I was able to write the following working code to draw any number of "sprites" (defined as 2 tringles, 6 vertices) ...
1
vote
1answer
44 views

If you can use subdivision surfaces for 2D curves

I've seen how subdivision surfaces are good for 3D curves/modeling, but haven't seen anything on if it's good, or even usable, in 2D. My question is just that, if (a) you can even use subdivision ...
2
votes
1answer
97 views

What algorithm is used in this animation from Tatami Galaxy?

Is there a name for this type of effect where many area sizes are increased/decreased in relation to each other? I'm looking for some type of algorithm, formula, logic, etc. for recreating this. Here ...
-1
votes
0answers
23 views

Understanding threshold finding in the Hough space in Python

I am following a tutorial on writing a Hough algorithm in Python: to my understanding it is very well written but I am new to computer graphic algorithms (not really used to thinking in terms of ...
0
votes
1answer
54 views

Problems with Subdivision Surfaces

It sounds like Subdivision Surfaces are better than NURBS but not as good as T-splines. I would like to know some of the disadvantages of Subdivision Surfaces, what they can't do or what they do ...
1
vote
0answers
81 views

Why do perspective correction based texture mapping do depth division

I'm currently trying to understand how works perspective correction texture mapping. I saw that actually it works by interpolating the z value of the three point of the triangle which the current ...
1
vote
3answers
197 views

How to calculate ray

In ray-tracing technique critical point is to calculate rays which came out from eye $E$ to target $T$ through pixel $P_{ij}$ on viewport. The "viewport" is represented as rectangle divided to square ...
1
vote
0answers
30 views

Convex hull around polygon for cave mapping

For the purpose of mapping caves, we survey new passages so that we take main polygon (survey from point A to point B) and on each "node" (survey station A in example), we shoot multiple "splay shots" ...
1
vote
2answers
79 views

How to get the 3D position for the point with (0,0) UV coordinates?

I have a 3D triangular mesh(vertices, indices, uv coords) that I'm rendering to the screen. Let's assume that the UV mapping is one-to-one. I'm trying to find a way to find the 3D position of the ...
2
votes
1answer
96 views

Naive Path tracer produces much darker images than Explicit light sampling

So I just thought of comparing the results from a Naive Path tracer and one using Next Event Estimation aka Explicit Direct Light Sampling. However the results from the Naive PT are very dark. Is ...
1
vote
1answer
75 views

Can't understand the Importance sampling GGX

I've read many articles relating to importance sampling of GGX. However, I still feel confused. The formula of GGX is : And many article says we should use this formula to sample: In the formula, ...
1
vote
1answer
34 views

How does a GLSL Sampler2D read a Vec2 UV coordinate to determine UV range

I am working with an atlas shader that steps through various sprite tiles within a single png atlas page to playback an animation with sampler2D. Looking at the shader code, I would expect to have to ...
0
votes
1answer
56 views

Convert shader from GLsl 1.50 to 1.30

I'm a newbie with OpenGl and I'm stuck in following the tutorial. I found this tutorial with these shaders ...
2
votes
0answers
52 views

What to reproject when doing temporal filtering in stochastic screen space reflection?

I am in the middle of implementing stochastic screen space reflection based on frostbite presentation here. On page number 39, it is stated that we need to reproject the ray intersection location ...
3
votes
3answers
761 views

Why Diffuse Light use max(N · H, 0) instead of just letting it be negative?

In Cg tuts, Diffuse Section Surfaces that face away from the light will produce negative dot-product values, so the max(N · L, 0) in the equation ensures that these surfaces show no diffuse ...
3
votes
1answer
109 views

Need help with change of basis (world to camera frame)

I'm reading up on coordinate systems and geometric transformations but the change of basis topic still confuses me. I found this exercise but, honestly, I wouldn't know how to begin: Given a world ...
1
vote
1answer
36 views

Make a texture a clickable Button

What would be the best way to make a texture a clickable button? Suppose I have a Room (respresented by a 2D texture), where there are buttons. Would I in the main loop: check when the mouse is ...
3
votes
1answer
71 views

Why don't Direct3D/Metal support texture swizzles?

To be clear, I'm talking about behavior like https://www.khronos.org/opengl/wiki/Texture#Swizzle_mask, not "normal" myColorVariable.rbgr swizzling in a shader. I ...
3
votes
1answer
200 views

Multiple Importance Sampling in Path tracer produces Dark Images

So I recently implemented Multiple Importance Sampling in my path tracer which was based on next event estimation. The problem is without MIS I get images like, This is obtained by setting ...
1
vote
1answer
80 views

Texturing an “infinite” plane

I am rendering an infinite plane as described in the following answers: https://stackoverflow.com/questions/12965161/rendering-infinitely-large-plane https://stackoverflow.com/questions/7380250/how-...
3
votes
1answer
129 views

Why does some text on my laptop have gray-scale pixels and some have color pixels?

In this question I generated the images below to explain why I can't use TTFs for that 1-bit display application. But now I would like to understand from the perspective of a non-expert, why is some ...
2
votes
1answer
98 views

Comprehensive explanation of conservative rasterization algorithm

I am trying to implement conservative voxelization as part of real time GI in my hobby rendering engine. I find this article by NVIDIA. I am stuck at understanding the second algorithm. The problem ...
1
vote
1answer
38 views

Export Model Textures Per Face

(Note that as far as attempts go, I can't find anything that helps me) I have a 3D polygon, and for simplicity's sake it's going to be the one below: It is textured using the UV map below: Side ...
2
votes
1answer
40 views

Composition of decomposed transformations

Say I have a scene graph, and each node has a scale, rotation, and translation. Can I combine these into a single scale, rotation, and translation?
1
vote
1answer
119 views

Get intersection Ray with square

I have a class Ray and Square public class Rayo { public Point origen; public Vector direction; Square{ X,Y,Widht, height; } I need intersection between this ...
2
votes
1answer
32 views

R16_FLOAT, SampleCmp and CheckFormatSupport

I want to use PCF shadow map on my d3d11 app. My shadow map is an R16_FLOAT texture. When I use SampleCmpLevelZero it didn't give a correct result. After enabling debug layer, it shows: The Shader ...
4
votes
1answer
59 views

How to shift color values of a single RGB channel

I’m a weaver and textile maker with no prior coding or programming experience. In researching and reading through posts on this and other message boards, I was able to find a lot of useful information,...
2
votes
2answers
83 views

Rotate a model or a view with mouse input to produce intuitive results

I am writing 3D graphics software in Java using the LibGDX framework (which is a front-end for OpenGL), and am baffled by a transformation problem. How do I rotate the orientation of the camera or ...
1
vote
0answers
15 views

What is best way to use wavefront material file color parameter Kd to set vertex color in MetalKit submeshes?

I am developing a MacOS program using MacOS MetalKit and ModelIO. The ultimate goal is to use the 3D model to analyze the acoustic properties of a performance space. Initially I'm just creating a ...
2
votes
1answer
48 views

What does GPU serialized mean?

With GPU isolation : multiple processes use the single GPU will be serialized, cause OOM easily link https://www.slideshare.net/mobile/Hadoop_Summit/deep-learning-on-yarn-running-distributed-...
4
votes
1answer
68 views

How much does driver quality affect Vulkan and DX12 compared to OpenGL and DX11?

Considering the fact that Vulkan and DX12 delegate most of the memory management / work scheduling tasks to the application itself, how much do drivers affect performance? To put my question into ...
3
votes
2answers
70 views

Why MOCAP data don't use simple point coordinates?

This might sound stupid for you but I really don't know how it works in the domain of 3d animation and motion capture, but I need to work with ASF/AMC files at the moment and I find it a little bit ...
2
votes
1answer
71 views

Rendering Equation for photons carrying flux

I am trying to understand the mathematical/physical foundations of photon mapping better. In the forward photon tracing step it is established, that the rays are carrying portions of total power (...
2
votes
1answer
50 views

3ds max: Z-fighting when working with Large Objects

I had a z-fighting/z-clipping issue with a scene containing some very large objects yesterday in 3ds max. It can be seen in the image below: For some reason downscaling the scene significantly (a ...
-1
votes
1answer
58 views

How can I make a cube with faces of different colors? Webgl

I have to draw cubes with faces of different colors (each per face), but I don't know how to accomplish this task: I draw cubes using CPU and GPU meshes (no vertexBuffer or three.js "style") and I don'...
3
votes
0answers
82 views

How can you avoid thin triangles in a parametric shape in a smart way?

I have created a closed 3D mesh using a parametric function. The shape is constructed by taking an arbitrary closed b-spline and scaling it based on one of the parameters (similar idea to a parametric ...
7
votes
1answer
78 views

Bitmap-images or SVG

I'd like to create a GUI in my first Unity-game (2D). I want my GUI appear sharp in all resolutions (e.g. 1920x1200 or 3840x2160). The problem I am facing now is that I don't know if I should save my ...
3
votes
1answer
138 views

Rendering Fluid Simulations?

I've read about Lagrangian and Eulerian fluid simulations and here's what I take from their methods: Lagrangian - Simulating fluid particles by calculating displacement for each particle Eulerian - ...
2
votes
1answer
42 views

Alpha component in color buffer affects RGB components?

I'm looking for a way to make my surface semitransparent, and for now i ended up using this configuration: ...
2
votes
1answer
82 views

How do I convert a hit on an infinite plane to UV coordinates for texturing in a Raytracer?

I am trying to convert a ray hit on an infinite plane, defined by an origin and a normal vector, into UV coordinates, so I can find the appropriate texel at that point. Code I have is close to ...
1
vote
1answer
47 views

How do I swap the buffers when using a Win32 window with Vulkan?

I was recently told here how to manage the integration between Vulkan and Win32. I am writing a windowing library like "GLFW", that is only going to support Vulkan; I have now come to the point where ...

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