All Questions

0
votes
0answers
3 views

Specular error - wrong TBN transformations

I have a problem with TBN matrices due to their transformation in world space. In .cpp I am trasforming my worldMatrix based on rotation: ...
0
votes
0answers
5 views

Non jagged line algorithm for javascript canvas

I'm trying to draw a line between two specified points, by updating values in an array which is heightxWidth with each element a set of four bytes (r,g,b,a). In my naive implementation I get the top ...
0
votes
0answers
14 views

sdl2: Compiler throws “Undefined Reference”

I'm trying to learn computer graphics, but when I tried to get this very simple windower running with c ...
0
votes
0answers
27 views

Sub pixel rendered white text on black background changes color when resized to a very small size

download: https://upload.wikimedia.org/wikipedia/commons/5/57/Subpixel-rendering-RGB.png The above picture is an example for sub pixel rendering. I tried resizing the image to very small size in ...
0
votes
0answers
17 views

Why cache working set per multiprocessor for texture memory in Nvidia has a variable size?

I saw it here https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#features-and-technical-specifications__technical-specifications-per-compute-capability , I don't know if it also happens ...
1
vote
0answers
29 views

Why don't I see tile-based 3D graphics?

As we know, tiles can make it quicker to update large portions of the display at once, as compared with a bitmap. To put, say a letter, on the screen, the Commodore 64 typically does two writes (the ...
0
votes
0answers
16 views

What is the difference between world coordinate, viewing coordinate and device coordinate in computer graphics?

The 2D pipeline involves with the construction of world coordinate scene followed by converting world coordinate to viewing coordinate, then transforming viewing coordinate to normalized coordinate ...
0
votes
0answers
15 views

How to rotate an object in OpenGL on the X, Y and Z axis on its local coordinates?

I've read multiple tutorials, but I still can't understand how do I properly rotate an object in 3D space on all 3 axis at once. For example, I'd like to give the object a pitch of 60 degrees, yaw of ...
0
votes
1answer
14 views

Multiple swapchains in Vulkan app with ImGui

I am integrating imgui into my app using glfw + vulkan example. The function vkCreateSwapchainKHR() is also called by imgui setup logic in addition to my app on the same device and it fails with "...
0
votes
1answer
39 views

shaderc compile through api with #include

I'm using shaderc to compile glsl code in to spirv module and pass to pipelie in REAL-TIME. I want to use #include to reuse some of the shader code but shaderc is having problems recognizing it. Any ...
0
votes
0answers
24 views

RGB map into numerical data

the image below uses an RGB scale (the values of the scale are displayed on the image) to show the magnetic field strength at each point on the map. I've been struggling to find a way to convert this ...
0
votes
0answers
20 views

Mesh Simplification Algorithms

I'm currently looking into Mesh Simplification to batch-simplify a large amount of .obj files. It is necessary for these algorithms to preserve the visual representation of a mesh as well as possible. ...
2
votes
1answer
40 views

Is vkCmdPushDescriptorSetKHR efficient?

I am new to Vulkan. Compared to DX12, the resource binding procedure seems a little bit complicated. In terms of per draw call uniform buffers, I currently have two approaches in mind, and they both ...
0
votes
0answers
27 views

Clarification about Phong lighting model

I've read some tutorials about Phong and Blinn lighting models and tried to implement a rendered myself. To my knowledge, the basic approach consists of the following steps: calculate the vector from ...
1
vote
1answer
43 views

Tone Mapping in a physically based rendering ray tracer

I'm implementing a pbr ray tracer. Let's say that I'm at the end of the process: for each pixel pi, I accumulated the radiance value in vector pi = (radR, radG, radB). At this point, these values are ...
0
votes
1answer
40 views

how to update my scene graph?

I am updating my scene graph in response to user input and the network. What is the best way to do this? The updating threads are separate. Some approaches I am thinking about: double buffer. There ...
0
votes
0answers
18 views

How to pass an SAH based BVH to the GPU using OpenCL

So I'm in the midst of implementing an SAH based BVH (the one implemented in PBRT) for my pathtracer. The whole path tracer is written inside an OpenCL kernel. Now I need to build the BVH on the CPU ...
0
votes
0answers
22 views

Confused on GPU Voxelization

I am learning how to voxelize a scene using GPU. In OpenGL Insights, there is a algorithm doing this on page 6. However, I am confused on the last step: Convert 2D fragment to 3d voxel. In the book, ...
0
votes
0answers
24 views

Algorithm for randomly generating polyhedrons?

I want to randomly generate polyhedrons which need not be convex. What is the most efficient way for doing so? I can think of an algorithm for generating random convex polyhedrons, but am unable to ...
0
votes
1answer
19 views

Unity: Pass texture pointer from OpenGL to Unity

I'm working on a scene in Unity where I have textures loaded at runtime. As a result of that, the scene is being slowed down (even with co-routines), so I thought maybe I could move the texture ...
0
votes
0answers
20 views

PostScript's readstring: Is there a more efficient way to parse lines? [migrated]

(I hope this is the most appropriate StackExchange site for asking PostScript questions, but I realize there is no "postscript" tag available) A very old PostScript code of mine that parses input ...
0
votes
1answer
35 views

WebGL Can't render anything, wrong projection?

I'm trying to understand and learn WebGL and computer graphics from button up, that is why I started to work on my own little library for that. I've spent couple of days looking for right answer and I ...
0
votes
1answer
36 views

Are non manifold meshes problematic for Virtual Reality?

A simple question. I know that non-manifold meshes are problematic for physics simulations, boolean operations, and 3D printing. I was wondering if they can be problematic for a virtual reality ...
0
votes
0answers
3 views

Linker Error in VS 2017 community with GLAD [migrated]

This code is a direct copy of an example. I have references set, however it appears that GLAD doesn't have a lib file; and I think that is what I am missing. Does anyone know a way around this issue?...
1
vote
2answers
272 views

How are colors really mixed?

I'm kind of stuck on this one. When following a conventional, high-level shading tutorial, you'll come across these images that are like ambient + diffuse + specular = result, but I can tell that it's ...
2
votes
1answer
36 views

Programmatically generating bin files for GLTF models

I have a need to generate a series of GLB files. I have a base template for a GLTF file which I have to derive off of. The models thus generated will only have varying textures on them. The base mesh ...
0
votes
0answers
36 views

Using octree for cheking intersection of ray and meshes

I wrote the code for checking intersection of ray and meshes on scene. It consist of two parts - broad phase and narrow phase. In broad phase I build an oriented bounding box around each mesh and ...
1
vote
1answer
50 views

gl_FragCoord and glViewport

I've been scanning the specifications for both OpenGL and GLSL, and I can't find a definitive answer as to how exactly are gl_FragCoord's ...
0
votes
1answer
26 views

Vulkan: efficient way to update VBO mesh vertices?

I would like to change/add/remove some mesh vertices in existing VBO's (while deforming and remeshing 3D objects) . With OpenGL I would have to reload whole vertex VBO's. I suppose with Vulkan there ...
0
votes
1answer
32 views

How to make the lines of a (binary) image dotted or dashed?

Let's say I had a binary image (i.e. only contains black and white pixels). For example, this one: How would I make all the lines in this image dotted or dashed? In other words, the eyes would be ...
0
votes
0answers
13 views

Export images in sketchup models

I built a model on Sketchup and imported png images in it to fill some faces. At first time, I tried to fill with a texture pointing to the desired image but it wasn't centered. Then when I export my ...
2
votes
0answers
47 views

How to project an image on spherical surface with least possible distortion

I did not know where to ask, I will try it here. I work in a local planetarium and I wonder if it is possible to edit an image in such way, that when projected on spherical cupola (diameter 8 m), it ...
1
vote
1answer
39 views

Why BMP file format last line of image is first line on file?

I'm studying Microsoft Windows Bitmap File Format, extension BMP. I'm curious to know why scanlines are stored on file from bottom to up: the last scanline on image is the first line on file and the ...
1
vote
2answers
62 views

How to calculate interpolation between multiple skeleton poses?

I found out that I should use spherical linear interpolation to blend two poses of a joint. I cannot find what to do if I have hundreds of poses to blend except applying the SLERP iteratively. What ...
2
votes
1answer
60 views

Why the Bresenham's algorithm does not work for those two points?

I am using the Bresenham algorithm from wikipedia: ...
0
votes
1answer
55 views

Factor of 2 converting radiance to irradiance

For a Lambertian surface, the radiance at a point is $$L = \frac{\alpha}{\pi}\cos\theta_i E_0$$ If we have an infinite flat surface, albedo = 1, illuminated directly normal, then we get $$L = \...
0
votes
1answer
63 views

Any good sources on advaced/special rasterization algorithms and techniques and theory behind them?

I spent quite some time looking for books on rasterization of vector graphics and related challenges. The best I found is "Raster Tragedy in Low Resolution",which is old and focused on fonts. There ...
0
votes
0answers
28 views

Where to store a very small set of shading constants in D3D12?

My rendering engine heavily uses implicit rendering techniques, so I have relatively little constant data to upload every frame (just 240 bytes of rendering settings; surface parameters are passed ...
0
votes
0answers
56 views

Programmatic rendering of 3D animations

Many years ago I used POV-Ray to render some 3D animations. I liked POV-Ray's Scene Description Language (SDL) as I could generate the required files programmatically using other languages (e.g. Perl)...
2
votes
0answers
98 views

Recreate geometry from normal map

I have a group of low polygon meshes, with associated normal maps. The normal maps were created by baking from high polygon meshes, which I no longer have access to. Is it possible to recreate ...
4
votes
0answers
124 views

Pre-filtered environment map, deriving the equation

I'm reading through this article, and more specifically I'm trying to derive the equation that would explain the implementation the following shader (still in the same article): ...
-1
votes
0answers
49 views

How can I draw a 3D crystal unit cell (NaCl as an example) on OpenGL?

I'm a physics a student and currently working on OpenGl. I have been searching for applications related to physics that could be simulated. I want to write a code for a unit cell of NaCl on Opengl. ...
3
votes
0answers
71 views

Microfacet GGX not integrating as expected

I'm trying to complete a look-up table for an energy-conserving variation of microfacet GGX as implemented here: https://patapom.com/blog/BRDF/MSBRDFEnergyCompensation/ I have a (pretty standard) GGX ...
2
votes
1answer
64 views

How is this normals map supposed to work?

I have come across this image that's labelled a bump map to be used with a 3D model. It looks like this: In this map, which is an RGB map, it seems we have pixels whose normals face upwards shaded ...
0
votes
0answers
29 views

gradual transition of light intensity formula

Imagine I have an x value that ranges from 1-100. The light source is pointed at x=50. From points 35 to 65 I want intensity to be 1 At the ends (ie 1 and 100), intensity should be 0 What formula ...
4
votes
1answer
62 views

Dealing with interpolated normals within a raytracer

I am trying to render a teapot within a simple raytracing that can handle reflection, refraction, and shadowing from point and directional lights. I am very confused about one detail of the raytracer ...
3
votes
1answer
98 views

Calculating the gradient of a triangular mesh

This question is regarding a homework assignment (want to be upfront because many people on stack exchange don't like helping with homework questions). I have a triangular mesh, which is defined by a ...
2
votes
1answer
48 views

Confusion about data types in Jensen's subsurface scattering paper

I am currently trying to implement Jensen's paper on subsurface scattering, but I am getting confused when I am trying to implement it in my pathtracer. I have questions about the data types of ...
0
votes
1answer
60 views

Nice way to make noise seamless (without tampering with the noise generator)

Here's the problem : I have multiple noise generators in my program I Can't change. Perlin Noise, Diamond Square, Voronoi, etc. Unfortunately for me, I want the noise to be tileable, no matter the ...
3
votes
1answer
55 views

Wrong color in .ppm file

I'm going through the rasterizer tutorial from Scratchapixel, but I encountered a problem with the generation of the .ppm file. Since something was off, I reduced the example to the bare minimum, so I ...

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