# All Questions

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11k views

### What's the difference between orthographic and perspective projection?

I have been studying computer graphics, from the book Fundamentals of Computer Graphic (but the third edition), and I lastly read about projections. Though, I didn't exactly understand what's the ...
78 views

### Finding the maximum number of disconnected fragments

In a plane, we have a convex polygon with n sides. What would be the maximum number of disconnected pieces / fragments if this polygon is clipped against a square?
214 views

### Affine Transformation

We have a matrix $$\begin{bmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{bmatrix}$$ This matrix represents a ...
807 views

### How does everyone count “Rays per Second”?

Recently I'm developing a Monte-Carlo path tracer. To measure my tracer's performance, I decided to implement a simple mechanism to count how many rays can it trace in a second. Then here comes the ...
916 views

### How to implement Constructive Solid Geometry in ray tracing with implicit surfaces (spheres)?

What I'm trying to do is to simulate refraction through biconcave lens described by spheres A, B, ...
107 views

### Global illumination leading to image variation

I have a 3D scene I use to generate some images which I then process in Matlab. I noticed that when global illumination (GI) is not enabled, rendering always generates exactly the same pixel-for-pixel ...
290 views

### Generate this kind of 2d burst or pulse algorithm?

I'm currently trying to develop a game using Cocos2d-x using C++. I really need to generate this burst or (donut-shaped) pulse. I'm having a difficult time how to generate such shape. At first, I was ...
346 views

### What is my GPU waiting on?

I am writing an OpenCL program for use with my AMD Radeon HD 7800 series GPU. According to AMD's OpenCL programming guide, this generation of GPU has two hardware queues that can operate ...
556 views

### Line segments overlapping

I have implemented line segments intersetion test and at the very same test I want to include the fact that if two line segments overlap each other partially or fully , it will be flagged as no ...
560 views

### Line segment intersection test and find the point of intersection

Thanks for the suggestions. Now I am doing it as follows: First off it is identified if two line segments intersect or not. And I am using the algorithm described in the book - "Introduction to ...
134 views

### How can I resize a rendered ray traced image?

Say I have rendered an HDR ray traced image with dimensions 1920x1080 (width x height) pixels and I want to instead represent it with dimensions 960x540. Assume as well that the image has not yet been ...
341 views

### Data structure and algorithm for clipping triangulation with leaf nodes of an octree

I have an application in which I am using an octree to store a volume mesh of axis-aligned bounding boxes (AABBs). Given a water-tight manifold triangle mesh, I need to: find if an AABB is ...
313 views

### Gamma setting in games - Why 3 icons?

Whenever I try to adjust gamma settings in a game, I am shown three different icons and usually asked to make sure the left-most one is barely visible. Example: What are the other two icons for?
171 views

### Creating an Object Orientated Bounding Volume

I'm attempting to test out the maths behind bounding volume algorithms (prior to ray tracing) using MATLAB. So far, I have successfully created the relatively trivial axis aligned bounding volume, ...
174 views

### Find the longest straight line between two points on surface of polygon

My shape is a slightly concave polygon, and I'd like to know the maximal diameter. I imagine a straight line between two points on the surface of the polygon, such that the line does not pass outside ...
2k views

### What kind of technology would be involved in the rendering of human nails?

There are many references related to the physically-based rendering of several natural features of the numan body, such as skin, hair, eyes. However, I could not find specific information about the ...
835 views

### Represent vector with arrow

Another code review question. I am trying to draw an arrow to represent a vector. I have started with an unit arrow with vertices defined as follows: ...
346 views

### Can't render multiple VAO's?

I'm a newbie to OpenGL and I was following a series by "thebennybox" on Youtube. Specifically his series on modern opengl programming. I thought I would try to implement his Mesh wrapper using the ...
124 views

### Parametrize set of unordered points in 3d space

Let's assume that we have some set of points in 3d space sampled from some arbitrary surface, without self intersections and mostly flat. Is it possible to get any parametrization over this set of ...
730 views

### How to blend World Space Normals

I am trying to blend two world space normals inside a shader. One comes from a tangent space normal map converted into world space using a classic TBN matrix and the other one is a mesh normal map in ...
736 views

### How to generate binary gltf array buffers?

I'm looking for any way which enables me to quickly generate gltf files including the conversion of plain array buffers (vertex, index, color, etc.) into binary (bgltf, glb, bin) files. I'm asking ...
722 views

### Is it possible to store the plain buffer data in gltf files?

The GL Transmission Format comes along with a JSON styled main file which basicly describes the scene and binary files which contain the buffers. I'm currently writing a WebGL library and I need to ...
144 views

### Image based lighting, tangent space coordinates, and optimization

When I saw an implementation of normal mapping that computed the TBN matrix in the vertex shader and converted everything (in particular the view vector and light vector) to tangent space at that ...
534 views

### Change particular color in an image

Suppose i have a image and I want to convert the portion of image that is red to blue(or any other color). One way to do this is extract red part of image using HSV or other color values and convert ...
30 views

### Why does the G1 term have a 2 in the numerator in Walter's formula, but not in Heitz's generalized formula?

In Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs, Eric Heitz derives the Separable Masking and Shadowing function as (P.83-84): In the mentioned Microfacet Models for ...
224 views

### What methods/technologies to reduce required performance for virtual reality are there?

I'm interested in virtual reality, but according to some sources, less than 1% of computers in use today have the necessary performance to run modern VR games, granted many of them are not intended ...
470 views

### Ray-tracing the Cornell Box results in really inconsistent image

So I have a vector of glm::vec3 containing the triangles for the classic Cornell Box called triangles. The Draw method casts a ray for each pixel on the screen and ...
632 views

### How to compensate low amount of rays reaching the light in a Path Tracer

I am trying to implement for research purposes a path tracer, but so far but results are not so good and I will explain you why. The general idea before getting to the code: I am working on paths ...
282 views

### Collision detection methods for 2D and 3D environments [closed]

I found many sites, books and articles, all about especifics algorithms, I listed some of them (like bounding boxes, bounding spheres, octrees and KD-tree), but any of these founds lists every ...
5k views

### Is Russian Roulette really the answer?

I have seen that in some implementations of Path Tracing, an approach called Russian Roulette is used to cull some of the paths and share their contribution among the other paths. I understand that ...
4k views

### How to load a model in .json in three.js

I need to load a model "somemodel.json" into my "movie.js".Can someone tell me where i am going wrong.I followed the steps given here. index.html ...
1k views

### How could I use bent normal map

This might be a general question but I have some difficulties about understanding baked bent normal maps and how to use it inside a shader in Unity. From what I understand, bent normals are ...
551 views

### Could we dispense the near clipping plane?

Would it be, at least theoretically, possible to render without a near clipping plane? Could raytracing ignore this perchance? Quite many budding 3d artists have a WTF moment the first time they ...
125 views

### inside and outside region identification from 2D contour

A 3D model is sliced against a plane and the resulting 2D contour is projected onto the plane. I am looking for an efficient algorithm to identify the inside and outside region of the contour. ...
198 views

### Unlit objects in deferred rendering

What is the best way to draw unlit objects with deferred? Like skybox, particles or just glowing objects? I thought about mask in alpha channel, check it in light pass and just set diffuse color but ...
6k views

### What is an index buffer and how is it related to vertex buffers?

I have a vertex buffer like this: 0.0, 0.0, 1.0, 0.0, 0.0, 0.6, 1.0, 0.6, 0.5, 1.0 I have the following index buffer: ...
43 views

### Trouble using java connectivity and data transmition on libgdx [closed]

Hello everybody i have a trouble making datatransmition with mine program just to give the idea im trying to move this blocks when i move mine cars Here I leave the encoding of mine server/client ...
1k views

### Computing camera front direction from Euler angles

I am new to OpenGL and Computer Graphics in general. Lately I was learning how to model a camera, specifically how to model the rotation of camera. I was introduced to Euler angles for this purpose. ...
797 views

### How to generate OSX Flurry screensaver

I want to generate video similar to OSX Flurry screensaver (screenshot, video), but I have no idea how it is made. Does anyone here has an idea about how it's made, its algorithm and method?
5k views

### How to properly combine the diffuse and specular terms?

As far as I understand, in a BRDF the Fresnel term is telling us the probability for a photon to be reflected or refracted when it hits a surface. The reflected photons will contribute to the ...
207 views

### Sine-based Tiled Procedural Bump

I am trying to implement this formula to generate bump but I am facing some issue. The result doesn't look the same it's much darker. Here is my result (without same parameters) but it is much darker ...
561 views

### Path tracer not rendering shadows

I am trying to implement for research purposes a gradient-domain path tracer. In order to achieve this step I first need a working Path tracer. I have been creating one so far but results are wrong ...
589 views

### Can Frameless rendering reduce latency? And, can FPGA do 3D rendering instead of GPU?

In virtual reality, the motion-to-photon time is very important. Oculus says it has to be less than 20ms. Maybe 10~15ms is better. Some people try to introduce Frameless rendering technology into VR. ...
1k views

### Cloud based VR would be the future?

According to the following assumptions, I think Cloud based VR would be the future: 1) Real world scene rendering needs ray tracing or other complex computing graphics technologies. It needs a lot of ...
152 views

### Can V-Sync avoid tearing? I think it can't. Am I wrong?

1) Update the front buffer will cause screen tearing, every one knows it. 2) But V-Sync, I think it still get the same issue. Why I get this idea? 2.1) When GPU flips to the back buffer, current ...
93 views

### Why does the integral of NDF over a solid angle equals the area where micronormals belong to that angle?

In Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs, Section 2.2, Mr Eric Heitz defines the distribution of normals as: And then, he goes on with the following assertion: I ...
781 views

### How are we supposed to fix brightness with square roots?

I recently watched this video that talked from a physics perspective how most of the ways we deal with color on the computer is incorrect because brightness is on a logarithmic not linear scale. ...
94 views

### Converting from 360 degree vr to rectangular

What I am interested in doing is taking a 360 degree stereo video (Oculus Rift etc), and a description of how the viewing direction changes with time (rather than reading from gyroscopes) and then ...