All Questions

4
votes
1answer
92 views

Conversion from cubic catmull-rom spline to cubic b-spline

I have a bunch of points that are the control vertices of a cubic catmull-rom spline. I would like to convert these to the control vertices of a cubic bspline. I believe I can do this using this ...
0
votes
0answers
22 views

How to rotate camera in CAD package application

I can rotate camera to change the view for the first person. But as I am working on a camera object for a cad package this isn't a first person or walk-through. I am not sure how to rotate the camera ...
1
vote
1answer
69 views

preserving z-values during projection?

Consider this figure for projection. There are two equations that give value for the xp and yp coordinates: $x_p=x.\frac{(z_{vp}-z_{prp})}{h}+ x_{prp}.\frac{(z-z_{vp})}{h}$ and $y_p=y.\frac{(z_{vp}...
1
vote
1answer
170 views

How to match Blenders polynomial lens distortion model with GLSL?

I'm trying to re-implement Blenders (libmv) polynomial lens distortion model using shadertoy, in order to apply the lens distortion in another application ideally by generating a STMap for that. I ...
5
votes
1answer
159 views

High variance in path tracing specular objects

I'm testing my path tracer for specular surfaces. Images rendered with my own code have very noisy appearance, and I think they look like variance. I use point light and the bunny is of mirror ...
2
votes
0answers
45 views

Binary representation of Pascal's triangle [closed]

I recently learnt about the binary representation of Pascal's triangle. Here is what it looks like I am a java learner. Is there a way for me to find the java source code to graph this binary ...
0
votes
1answer
169 views

finding the projection matrix for one point perspective

I found the derivation for two point and three point perspective here on this site, even though it says review on one point perspective, it doesn't give a link to previous pages, but I'd like to ...
0
votes
1answer
179 views

perspective projection transformation matrix

In one text, the derivation for perspective projection goes like this: If $x',y',z'$ represent any point along the projection line,and $x_{prp},y_{prp},z_{prp}$ are the projection ...
3
votes
0answers
158 views

ray-triangle intersection precision - c++

I'm building a software renderer but I think there might be some problem with my ray-triangle intersection accuracy. I implemented the algorithm referring to ...
2
votes
1answer
97 views

Ask for detailed derivation of a formula in “Advanced Global Illumination”

Attached is page 34 of "Advanced Global Illumination", 2nd edition, by Dutre et al. I don't understand how (2.22) is derived from (2.21) and the given incident radiance distribution $L(x\leftarrow\Psi)...
2
votes
2answers
169 views

How can I draw this style of grid?

I'm trying to write code (in any language) to render this 3D grid, matching the look and colors as closely as possible:
0
votes
1answer
67 views

Adding vbos to a vao once it has been created

Is it possible to add vbos to vbos after their creation? For example (pseudo-code): ...
2
votes
0answers
65 views

Can you disable strip cutting (AKA primitive restart) on Direct3D 11?

Line strips and triangle strips are drawing modes supported across 3D graphics APIs, such as OpenGL, Direct3D, and Vulkan. When using indices to control drawing, a more recent feature is "strip ...
1
vote
0answers
42 views

Cook-Torrance Specular BRDF Artifact [duplicate]

I am currently experiencing a very obvious artifact that occurs when looking at objects on very grazing angles Here is a picture of the artifact: I noticed that the issue was coming from my ...
0
votes
1answer
109 views

3D scene construction and change of coordinates

My book says: After a scene has been constructed we transfer object descriptions to the viewing-coordinate reference frame. This conversion of object descriptions is equivalent to a sequence of ...
1
vote
1answer
24 views

Converting color to equivalent with opacity

Assume a color X with alpha 1 and RGB 255,230,210. How can i find another color with alpha A ( or an array of colors ) that blended with a background of color Y ( e.g 255,255,255 ) would produce the ...
7
votes
1answer
88 views

Do operating programs such as Microsoft Office or Windows Explorer use OpenGL to draw?

I have a server and my only monitor is plugged into its graphics card. My question is - do all programs (Windows explorer, Excel whatever) draw their output using the graphics card and more ...
2
votes
1answer
48 views

What is the equivalent of rotation matrix in Euler angle space for Quaternions?

I have to load a mesh in Blender (which uses Z and Y as up and forward axes), modify it and export it (with setting up and ...
0
votes
1answer
75 views

How to include OpenGL extension loader in my project

I have a modern OpenGL project hosted publicly. I want to create the easiest experience so someone can just clone the repo and have it just work. So far, I have included (as git submodules) the ...
1
vote
1answer
56 views

How to rotate a shape in another 3D software so that the rotation matches with the rotation in Blender?

I import a mesh in Blender, export it with setting axis_forward='-Z', axis_up='Y', import in NVIDIA's FleX, rotate it and store it on disk; I call this mesh ...
1
vote
1answer
80 views

Using depth texture to mask local pixels

I have a scene with camera facing billboards drawn with depth write off so they appear on top of other objects. I would like to draw each sprite so that any obscured pixels are drawn with a very low ...
3
votes
2answers
126 views

Which graphics APIs texture formats are HDR texture formats?

I understand that HDR files are images encoded with a higher precision in order to keep more details. When loading such images in real-time rendering applications using common Graphics APIs (DirectX, ...
0
votes
1answer
53 views

How to compute A and B in projection matrix

I'm trying to compute a projection matrix to transform from view space to NDC with a near clip plane at -1 and far plane at +1. The general form of this matrix (disregarding aspect ratio and focal ...
1
vote
1answer
72 views

Wrong tangential directions for cubic bezier curve

I am well aware that there are several ways to find the tangents to a Bezier curve. However, I choose to just substitute the result of differentiating the Bezier curve equation. So, given four ...
8
votes
1answer
3k views

Raytracing: why are the spheres in the image below appear stretched?

Some context. Above are the code and the resulting image for it in Peter Shirley's Raytracing in one weekend's book. As you can see from the code, he adds in some spheres. And yet in the final image ...
0
votes
1answer
78 views

qt - view geomview (.off ) file

I want to open a .off file and view the content 3d model using libQGLViewer, qt-creator. I don't know how to display the 3d model after opening its .off file. ...
2
votes
0answers
67 views

Plotting software used in old scientific papers

Does anyone know what software was used in many old scientific papers (please see attached example). I love the clean look of the graph and the typeface. Thanks. Graph example
0
votes
1answer
46 views

Resolution issue of generating a PNG icon for macOS menu bar

Wonder if anyone has experienced this. When generating png image icons for macos. its recommended at 19x19 pixels. However, based on that, the icon (shield) that is generated is pixellated compared ...
1
vote
1answer
56 views

What objects do get loaded into GDDR?

I currently have a 4K monitor and want to buy a new graphics card. My choice would either be the RTX 2080 or the RTX 2080 Ti. Now I need to know which one I really need. The Ti variant has 12 GB of ...
3
votes
1answer
1k views

How to convert Euler angles to Quaternions and get the same Euler angles back from Quaternions?

I am rotating n 3D shape using Euler angles in the order of XYZ meaning that the object is first rotated along the X axis, then Y...
4
votes
0answers
40 views

Does MRG32k3a compare well with PCG and Xorshift256*?

I've been using standard 32-bit Xorshift in my GPU path-tracer for a while, following Nathan Reed's approach with hashed seeds and decorrelated state. I (finally) discovered today that Xorshift is ...
0
votes
1answer
163 views

GLSL Debugging Volumetric light

I'm implementing basic volumetric lighting using deferred shading (gbuffer + render to screen quad) and basic shadow mapping. So, I am sending the position texture and shadow map to a separate shader,...
1
vote
0answers
25 views

D3D12EnableExperimentalFeatures causes D3D12CreateDevice to fail

I am following Nvidia's DXR tutorial: D3D12HelloTriangle. I call below code before creating device and it returns true ...
5
votes
1answer
66 views

How to randomly draw Quaternions within a specific range of Euler angles for rotation?

I am pretty new to Quaternions so please bear with me. I want to draw random Quaternion samples so that their Euler angle equivalent would range within [-30, +30] ...
1
vote
2answers
104 views

WebGL - issues doing a simple texture downsample

I'm working on an image processing app which uses WebGL to apply shaders to a bunch of input photos. At one point in the algorithm, I need to create some image pyramids where I downscale the input ...
4
votes
1answer
281 views

What are Metal and Vulcan?

I keep coming across the terms 'Metal' and 'Vulcan' on this site. Guessing this to be some CG software, I'm interested to know what these are exactly and what the intended and most common usage is. A ...
1
vote
1answer
78 views

Why is pixel 0,0 at the top left of some formats and bottom left of others?

It seems that every image format (jpeg, png, tiff, bmp, jp2000...) doesn't place their origin at the same corner. Do you know where I could find some info about this differences? I can only say that ...
2
votes
0answers
52 views

Identification of visible area of a plane in OpenGL

I have somewhat generalized version of this question: https://stackoverflow.com/questions/52475104/how-to-show-visible-part-of-planar-world-rendered-with-3d-perspective-on-topside -‎ I would also like ...
1
vote
1answer
73 views

How are the three plane equations derived in the NVIDIA's CG Tutorial chapter 8?

I'm reading the chapter 8 of the Cg tutorial and I could not understand 8.4.1 : Because all these coordinates lie in the plane of the same triangle, it is possible to derive plane equations for x, ...
9
votes
2answers
100 views

Why replicating the higher bits of RGB565 when converting to RGBA8888?

I have seen in some computer graphics software's code bases that sometimes the higher bits of RGB565-format image data are replicated into the lower bits when converting to higher-bit-depth format ...
0
votes
1answer
37 views

Confused about graphic art and what software is used to create the environment of it? [closed]

I have a question that I am stuck on, I am wondering what style is this image considered? And what program do people generally use to create this?
1
vote
1answer
60 views

What is a “Vulkan Extension”?

When creating a VkInstance, you need to setup the API's extensions that are going to be used by your application (for example you need an extension to interface with the window system on desktop ...
2
votes
2answers
229 views

What's the point of “work groups” for OpenGL compute shaders?

glDispatchCompute has the number of work groups as arguments. What is the point of having work groups? How are they useful, compared to just having NxM independent pixel calculations with a known (x,...
7
votes
1answer
186 views

How does this small fractal shader work?

I would like to know the magic behind this tiny fractal shader; I didn't really understand the code and the mentioned thread... Is there an accessible explaination? https://www.shadertoy.com/view/...
4
votes
1answer
80 views

Hodge Decomposition in fluid simulations

I have just started implementing a fluid simulator based on the navier stokes equation. I am following Jos Stam's paper to do so. In this paper, it says that the velocity field must be mass conserving....
2
votes
1answer
157 views

What is shader warming, and why does Direct3D seem to avoid it?

I am involved in a project that had been modified to run on Apple and Linux computers, when it was originally Windows only. Specifically, Metal and Vulkan renderers have been written alongside the ...
5
votes
1answer
114 views

Surface fairing, implementation detail

I'm reading through Polygon Mesh Processing, section 4.3 (Surface fairing). The reference I mentioned defined defines "Surface Fairing" as The goal of surface fairing is to compute shapes that are ...
2
votes
1answer
110 views

Computing perspective directly

Assume the screen is axis aligned with origin at 0 and there is absolutely no view transformation. in other words we will simply try to project the model onto the screen plane following perspective. ...
1
vote
0answers
141 views

Understanding bad shadows with voxel ray tracing

I have a voxel raytracer that is generating some weird shadows and I want to understand what is the source of the problem. The image is voxelized, resulting in: I then generate Hard shadows from the ...
4
votes
1answer
95 views

How to apply wire texture for realistic rendering of embroidery?

I am building an algorithm which takes a bitmap image as input and render the image as an embroidery design. The different steps are : Vectorize the image, I keep only 5 colors (Done) Generate ...

15 30 50 per page