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1answer
15 views

How are obj files textured?

I am a new learner in 3d graphics. So forgive me if I seem to ask something very basic. I am confused how obj files are textured. So far I have seen: obj + jpg obj + mtl + jpg When I look online, ...
2
votes
2answers
105 views

What exactly is the orthographic projection used by Matlab

I would like to imitate the orthographic projection that Matlab uses by default: Matlab View Projections and Matlab camproj It seems similar to the "Trimetric" projection described here: ...
1
vote
1answer
81 views

Why is the image from the CUDA version not as sharp as the CPU version?

I am extending Roger Allen's Ray Tracing in One Weekend in CUDA (and also here) by following Peter Shirley's Ray Tracing: The Next Week; specifically Image Texture Mapping. The image I obtain from ...
0
votes
1answer
12 views

How is the multiplication in Gaussian Blur implemented

I have a question regarding how the Gaussian blur works. A pixel consists on the combination of 3 colors: R,G and B. I have read that the Gaussian kernel is multiplied by the input image by placing ...
2
votes
1answer
103 views

An idea for an implementation of continuous collision detection of circles

So I'm making a 2D pool game in OpenGL (you might've guessed as soon as I've mentioned collision of circles). I'm having a little trouble with collision detection. What I mean by that is that I have ...
1
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0answers
8 views

What is the best way to calculate the projected size of a point

In a particle simulation, I am rendering particles as "spheres" using GL_POINTS instead of a mesh for efficiency. With glEnable(GL_PROGRAM_POINT_SIZE) I ...
0
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0answers
9 views

How to intercept call trace in OpenGL

I wonder how software like apitrace is able to output the call trace in OpenGL. Are calls to GPU possible to intercept for a given frame?
0
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0answers
9 views

Silhouette below 3D model

There are some 3D applications which can cast shadow or silhouette below 3D models. They render pretty fast and smooth. I wonder what kind of technology is the standard procedure to get 3D model ...
4
votes
1answer
372 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 ...
1
vote
1answer
26 views

How does the GPU know whether to magnify/minify?

Let me first state what I think I know and please correct me if I'm too inaccurate or plainly wrong. When you use a function like texture, you're requesting a texel value given a pair (u,v) of texture ...
0
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0answers
33 views

Model View Projection Matrix Multiplcation Order

I'm working on a simple software renderer and have a working implementation so far. I'm curious as to why it's actually working since I would expect the multiplication ordering for my world, view and ...
0
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0answers
19 views

Changing shader color

I have the following .fx file for my shader: ...
0
votes
1answer
115 views

What is the PDF for path tracing in the paper "Learning the light transport the reinforced way

It's the algorithm which combines path tracing and reinforcement learning. I can't understand what $p_\omega$ is. The algorithm is clear. The actions are the directions and the states are the hit ...
0
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2answers
55 views

What exactly is it about reality that is so difficult to recreate in a 3D simulation?

I have to admit that, while watching footage of the enhanced 2020 version of the 2018 game Forza Horizon 4, when they are driving fast, I have to sometimes remind myself that I am watching a video ...
0
votes
1answer
59 views

Keep constant number of visible circles in 3D animation

I have created a 3D animation with a perspective projection of white circles moving randomly in a fake 3D space projected on a 2D computer screen (GIF 1). Since I need to keep the same number of ...
0
votes
0answers
10 views

Backface culling in DX12 not working properly

I've modified code of my path-tracer to rasterization only, to play a little with DirectX 12. However, I have problem with correct backface culling, even though my PSO seems to use correct options: ...
0
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0answers
7 views

Calculating minimal voxel size in a mesh

I am developing a script that will determine a minimal voxel size in a mesh. My first thought was to caculate the area of given face. Another approach would be to calculate minimal line length and ...
1
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0answers
16 views

GL_OUT_OF_MEMORY Error when glDispatchCompute takes longer

I built a simple Ray Tracer which takes use of OpenGL's Compute Shader and traces ".obj" Files. The results are passed to the Host-Program via glMapBufferRange after finishing computing. ...
2
votes
1answer
611 views

Feeding vertex data to a compute shader

I'm writing a CAD program in vulkan. In my current design, I have line paths represented as large vertex buffers for rendering. I would like to implement an algorithm for extruding the path outwards, ...
0
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0answers
35 views
+50

Algorithm to select regions based on curvature on a mesh

I'm trying to understand how to implement an algorithm similar to the one used by Magics' mark surface tool, you can see such behaviour on this video. Quoting the video: "Basically with this tool ...
0
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0answers
21 views

Is There an algorithm to remove intersections between two tetrahedrons?

I have a mesh made up of several tetrahedrons, I know for sure that there are intersections between some of them: how can I remove these intersections, without generating others? In other terms: if ...
0
votes
2answers
127 views

Properties of the image reconstruction filter in rendering

Let $f$ denote the measurement contribution function for paths of length $k\in\mathbb N$, i.e. $$f(x)=g(x_0\leftrightarrow x_1)W_{\text e}(x_1\to x_0)t_k(x_0,\ldots,x_k)L_{\text e}(x_k\to x_{k-1}),$$ ...
2
votes
1answer
69 views

Ray tracing where illumination itself affects the geometry

I am interested in a scientific application in which ray tracing is necessary, but also where the light itself alters the geometry of the surface mesh (imagine perhaps that the beams of light have ...
1
vote
0answers
39 views

Blur calculation in shader with fixed CoC

I have just started learning how to use and create shaders in ThreeJS and, while going through some shaders in the example folder, I have come across a bokeh shader. Inside the shader, blur is ...
0
votes
1answer
24 views

Calculate the position and rotation of a quad in 3d space given a 2d projection of that quad from a camera

I am trying to build a VR tracking system with a laptop webcam, and I have succeeded in identifying, and tracking paper markers I put in front of my webcam. For context I am using OpenCV with the ...
0
votes
2answers
68 views

Lambertian shading illuminates all the front of a sphere

I've sucessfully implemented a ray tracer from scratch in C and it's marvelous: The surface normal on this sphere is taken by computing the intersection point, A, and treating this as a euclidean ...
0
votes
1answer
53 views

Looking for a compact file format for outputting 3D geometry with color support

I am looking for a file format to output some 3D geometry. In my case, it only needs to handle very simple shapes - uniformly spaced and sized cubes at points in space. So far I've ended up just ...
3
votes
1answer
568 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 ...
3
votes
0answers
88 views

IBL looks too dark with uniform sampling

I'm making a program that illuminates a sphere using an environment map. For each fragment in the sphere, I compute a many random directions in the hemisphere along the surface normal (no importance ...
0
votes
1answer
27 views

Is glDispatchCompute(a,b,c) any faster than glDispatchCompute(a*b*c,1,1)?

In my application, there is no inherent 2D or 3D structure to the computer shader instances. So having multiple dimensions doesn't benefit me semantically in any way. I am wondering, whether it still ...
0
votes
0answers
19 views

Identifying 2d coordinates of texture from 3d textured sphere

this is best explained by visualization. Below webpage is a spherical textured panorama which gives the effect of being inside of the room. I want to be able to localize (eg) windows by mouse clicks ...
0
votes
0answers
36 views

How to deallocate memory for vertex buffer objects

I have a class that handles loading buffers for a mesh: ...
0
votes
2answers
63 views

Using imageLoad/imageStore to perform atomic add

I have a rgba16f texture that I fill with values using nvidia GL_NV_shader_atomic_fp16_vector extension, which allows to perform ...
3
votes
1answer
307 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 ...
1
vote
1answer
75 views

Too soft shadows from multiple suns

I want to render the transient shadows due to the sunlight over a day in one image. So I placed all the suns, as directional light, in the scene. However the shadows in the rendered image(a raytraced ...
0
votes
0answers
52 views

Is there an existing method to draw a heart of stars that looks more like a heart?

I wrote a C program which prints a heartbeat (heart star) animation. The key is to print a heart of stars, which looks like this consists of line of stars and blanks. ...
0
votes
1answer
46 views

Vertices, Vertex Normals and Face Normals

Using Open 3D Model Viewer, I have converted an OBJ file to an STL file. In the source file, the Vertex Normals are specified and in the destination, the face normal of the triangles are present which ...
0
votes
0answers
33 views

Matrix transforming with translation/rotation/scale at center of screen

I'm trying to create a camera using matrix transforms, the gist as follows: ...
9
votes
1answer
534 views

Using Monte carlo on Rayleigh scattering

Update I am editing and posting this question in a different way; this time from the point of view of Nishita paper. Sunlight gets scattered at P and attenuated before reaching Pv. Therefore ...
0
votes
0answers
18 views

What sort of implementation dependent limits for glPointSize can one expect from modern graphics cards?

As noted here, when rendering using the GL_POINTS primitive, there is an implementation dependent limit to the point size range. I intend to use GL_POINTS for fast billboard rendering of particles, so ...
11
votes
1answer
871 views

Why do adjacent triangles never overlap when rasterized?

Apologies for the following noob question, it's just I can't find a satisfactory answer anywhere... When I render a simple axis-aligned quad made up of two triangles, I don't understand why there's ...
0
votes
1answer
46 views

Operations in the Rendering Pipeline

I have a few short question regarding operations happening in the rendering pipeline (OpenGL, Vulkan, I'd expect for all questions to have similar answers for these two frameworks while DirectX might ...
0
votes
1answer
22 views

THREEjs: updating an object's matrix doesnt change it's position and rotation params

I want to set a transformation matrix to an object upon creation and then control it by position, rotation and scale, but while changing the matrix does change the object in world space, it's position ...
1
vote
2answers
107 views

Defining “inside” and “outside” of a 3D space

I am not sure if this is the correct SE to ask this question. However, lets say I have been given 3D models of several enclosed spaces. I want to populate spaces with, lets say, planes flying through ...
1
vote
2answers
46 views

BVH uses aabb for a sphere in Ray Tracing: The Next Week

While studying Peter Shirley's Ray Tracing:The Next Week, I came across an issue that I cannot quite figure out: Stepping through the random_scene() case of the ...
0
votes
0answers
37 views

Can surface normal be used for obtaining points on a plane?

Excuse my wording. I will use the picture below to explain what I mean. I want to use the surface normals for each arrow shown like below to draw lines parallel to each plane like the image shown ...
0
votes
1answer
33 views

Drawing a square using glDrawArrays with GL_TRIANGLES

I used a version of the following code to draw a triangle using glDrawArrays with GL_TRIANGLES, per Anton Gerdelan's very nice tutorial here: Hello Triangle ! It draws a nice triangle. I have modified ...
0
votes
2answers
551 views

How can i wrap the earth image around a 3D Sphere using OpenGL, GLFW, GLAD, GLM?

Please help me out with this thing and currently i am a little more than a beginner so please tell me in that context. i don't need any obsolete methods for creating this like using GLUT or GLEW.can ...
15
votes
1answer
13k views

World coordinates, Normalised device coordinates and device coordinates

Can I get to know the difference between the three? A good example would add up too.
0
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0answers
20 views

How to update large step probability when exchanging states in Metropolis Sampler?

I want to implement good path guiding for photons for my Vertex Merging integrator. After reading through this 2 papers: Hachisuka T., Jensen H. W.: https://www.ci.i.u-tokyo.ac.jp/~hachisuka/...

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