# Questions tagged [rendering]

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### Why do Vertex Buffer Objects improve performance?

From my basic understanding, a Vertex Buffer Object works something like this (pseudo code): Normally, if one wanted to say, draw a square, one could issue line drawing commands. ...
2k views

### Perspective Correct Texture Mapping

So I'm trying to correctly map my textures in my software renderer using the u, v coordinates but I can't seem to get it working. I got affine texture mapping working. This is what I can produce using ...
615 views

### Multiple Importance Sampling in Path tracer produces Dark Images

So I recently implemented Multiple Importance Sampling in my path tracer which was based on next event estimation. The problem is without MIS I get images like, This is obtained by setting ...
740 views

### How to calculate the RGB intensity values at center of face using flat shading?

Consider a triangular face of three vertices A(0,2,1), B(3,0,1) and the origin, and the normal vectors at the vertices are nA=(0,0,1), nB=(1,1,0) and nO=(-1,-1,1), respectively. The incident light is ...
2k views

### What is the “dipole approximation” for subsurface scattering?

If you read papers about subsurface scattering, you'll frequently come across references to something called the "dipole approximation". This term seems to go back to the paper A Practical Model for ...
2k views

### Correct Specular Term of the Cook-Torrance / Torrance-Sparrow Model

For a while I have been doing some research on the topic of Physically Based Rendering. One reflection model that is mentioned over and over is the Cook-Torrance / Torrance-Sparrow model. It seems ...
4k views

### Physically based rendering and ray tracing

I've got a lot of confusion and I need to clarify some terminology and put together the knowledge. If I say that an engine is a ray tracer (so it uses the ray tracing algorithm to render the scene), ...
410 views

### What physical properties are “lacking” to keep this 3D scene from looking like a real photograph?

So I know that I'm basically asking to identify the main problem to be solved in creating realistic 3d Graphics, but as someone without much technical experience in the field, I'm curious that if ...
2k views

### What is the difference in overlay and framebuffer?

I have been trying to understand display and graphics. I feel that it's hard to make a logical image of the terms. I understand this: Frame buffer is a dedicated memory that has the image/video/...
597 views

### Energy conservation of BRDF

I'm reading Advanced Global Illumination. Here is the part confusing me: What do the second equation and $\delta$-function mean? Why the third equation is a sufficient condition even though a reason ...
615 views

### Trying to implement Microfacet BRDF but my result images are wrong

I am trying to implement microfacet BRDF model. I am reading Sebastien Lagarde's slides. I implemented formulas to my code but i think result image is wrong. Yellow is base color of material. ...
796 views

### Resulting Probabilty Density in Path Tracer for paths using Next Event Estimation

I am trying to implement my own Gradient Domain Path Tracer by following the code of this guy who already implemented it: https://gist.github.com/BachiLi/4f5c6e5a4fef5773dab1 I already managed to ...
2k views

### Multiple VAO share a VBO

Let's say I have a have 10 different terrains. Each terrain have the same x and z coordinates, but they have different y coordinate, normals and colors. The indices used for element rendering is also ...
218 views

### Why for perfect reflections a surface must have G2 continuity?

Why for perfect reflections a surface must have G2 continuity (class A surface)? I would like a mathematical answer.
551 views

### How should I fill a shape consisting of Bezier curves and straight lines?

I have been working on a graphics library for some time now and have gotten to the point where I have to draw Bezier and line based fonts. Up to this point I am stuck with this: The green lines are ...
158 views

### Proper architecture for rendering history of streamed data (points)

Overview My program receives some data points (0-400 per sec). ...
202 views

### Mix shader looks wrong on my path tracer

I apologize if my methods seem way off because this is my first time trying to build a path tracer and I'm struggling quite a bit. Currently, I am trying to mimic the "mix shader" node in Blender 3D ...
239 views

### Rendering same vertex-array in different modes

here is my vertex array I am using: ...
Consider a triangular face of three vertices $A=(0,2,1)$, $B=(3,0,1)$ and the origin $O$, with normal vectors $(0,0,1)$, $(1,1,0)$, and $(-1,-1,1)$, respectively. The incident light is white and ...