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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 ...
1
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1answer
16 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, ...
1
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0answers
9 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 ...
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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?
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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 ...
1
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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 ...
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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 ...
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0answers
19 views

Changing shader color

I have the following .fx file for my shader: ...
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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. ...
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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 ...
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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 ...
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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 ...
1
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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 ...
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 ...
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
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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
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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
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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 ...
1
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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 ...
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0answers
36 views

How to deallocate memory for vertex buffer objects

I have a class that handles loading buffers for a mesh: ...
3
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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 ...
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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. ...
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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: ...
0
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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 ...
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
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
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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 ...
1
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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
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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 ...
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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0answers
17 views

Packing a GL_RGB from three separate buffers?

I'm decoding an .mp4 to use as a texture on a tristrip. It's easy enough to use an unsigned byte array of RGB triplets to create this texture, but frames come out ...
0
votes
1answer
25 views

Problem sampling uniformly envmap with GGX

I have made a program that samples uniformly an environment map and computes the lighting using the GGX BRDF. I have made a small example that reproduces the issue I'm having. You can check it out ...
2
votes
1answer
37 views

How to draw surface normals from surface normal maps?

Using deep learning to estimate surface normals from monocular RGB images is a common task. The resulting image generally looks like this: My question is how can I use this map to actually draw a ...
0
votes
1answer
28 views

How to visualize density data as volume using OpenGL?

I have a CT scan of a portion of a human body, with each point describing density. The data file provides X, Y, Z, and density values. I want to know how to visualize this data, using OpenGL or a ...
-1
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0answers
28 views

How to split vertices during UV Mapping?

I'm currently implementing UV Mapping with Box Gizmo. It is the same function as the image below. (Box Projection UV Mapping in 3ds Max) As above, I have implemented texture mapping to the model. (...
2
votes
1answer
62 views

Debugging refraction in a sphere

I have been working on recreating some of the scenes from Peter Shirley's raytracing books using compute shaders and the new Metal raytracing API. It is going well but I am having some trouble with ...
0
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0answers
23 views

What do you do when the root skeleton is not defined in a gltf file?

Cross posting from stack overflow: Reading the source code of tinygltf I see this: ...
2
votes
1answer
51 views

Is there different between 'if' and 'ternary operator' in GLSL?

I'm practicing GLSL on ShaderToy ...
0
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0answers
29 views

How to render a rotated raster image with lesser aliasing

I am wondering about techniques for rendering a rotated and or scaled raster image. Currently I use the following algorithm Render everything at double resolution and store the result in ...
1
vote
1answer
79 views

Rendering a particle system as a smooth blob

What is a good algorithm for rendering a particle system as a coherent mesh, in realtime? I am running a smoothed-particle hydrodynamics fluid simulation, and I would like to render the particles not ...
0
votes
0answers
47 views

Can ambient light reflection of a surface be larger than diffuse reflection?

According to Phong's reflection model, there are different reflection constants (k) and different intensities of the light source (i) for ambient, diffuse, and specular terms: $I_p=k_ai_a+\sum_{m \in ...
0
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0answers
51 views

Different OpenGL behaviour on Windows and Ubuntu

While porting this project with slightly modified code to Linux I ran into some weird behaviour. On Windows it runs just fine (https://youtu.be/xH6Dc6xOuow). But on Ubuntu it shows some weird ...
3
votes
1answer
111 views

How do we know if a ray intersected a triangle in one in a million

I've taken a class about ray-plane intersection on this: https://www.khanacademy.org/computing/pixar/rendering/rendering-2/v/rendering-5 Suppose we shoot a ray at the scene and this scene contains ...
1
vote
1answer
133 views

Energy redistribution sample re-integration

I'm implementing ERPT-style energy redistribution of primary samples within a pathtracer. Specifically, to improve the sampling of defocused areas. The core algorithm does two things: If sample ...
1
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0answers
40 views

Layer rendering in Vulkan

I am writing a Vulkan video manipulation engine which has the following layers: Foreground (2D) Scene (3D) Background (2D) Note that each layer may have multiple objects, some of which may be ...
1
vote
1answer
44 views

projecting 3d onto 2d plane is not showing up correctly

I am trying to learn about 3d graphics from first principles, so i have decided to implement a simple thing, create a circle in 3d space & rotate it along some axis. I understand the basics theory....
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 ...

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