# All Questions

2,341 questions
8 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 ...
10 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 "...
38 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 ...
22 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 ...
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### 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. ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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 ...
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### 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, ...
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### 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 ...
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 ...
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### 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 ...
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### 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 ...
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 ...
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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?...
271 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 ...
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 ...
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### 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 ...
48 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 ...
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 ...
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 ...
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### 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 ...
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### 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 ...
38 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 ...
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### 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 ...
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### Why the Bresenham's algorithm does not work for those two points?

I am using the Bresenham algorithm from wikipedia: ...
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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 = \...
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### 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 ...
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### 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 ...
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)...
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 ...
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): ...
48 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. ...
70 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 ...
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 ...
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 ...
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 ...
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### 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 ...
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 ...
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 ...
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### 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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### How do I represent the grid patterns of the image in the included figure with a DITHER MATRIX?

The problem statement is: "Represent the grid patterns in [the the figure linked below] with a dither matrix." The figure is: https://www.docdroid.net/d90WXko/figure.pdf Apparently, according to the ...
Perfect mirror's brdf is simple, $F\frac{\delta(\omega_i-\omega_r)}{|\cos(\theta_r)|}$ as in http://www.pbr-book.org/3ed-2018/Reflection_Models/Specular_Reflection_and_Transmission.html As shown in ...