# Tagged Questions

54 views

For a while now I used PCSS for my shadow technique of choice until I discovered a type of percentage closer filtering. This method creates really smooth shadows and with hopes of improving ...
110 views

### The math behind Variance Shadow Maps - moments

I am not asking how to implement them (that's not particularly difficult), but I'm having a bit of trouble understanding why the moments used in Chebyshev's inequality (indirectly) are equal to the ...
99 views

### Smooth Ramp to zonal harmonics

I have written in blitz3D some code to generate arbitrary 2D lighting lookup textures and I'm looking for a way to compress them. The idea is that they look rather smooth and low frequency, there must ...
65 views

### Surface normal to screen angle

I've been struggling to get this working. I simply wish to take a surface normal and convert it to a screen angle. As an example, assuming we're working with the highlighted surface on the sphere ...
213 views

### Directional light and matrix issues

I'm trying to implement basic directional lightning in OpenGL 3.3 by emulating the logic shown in this guide: http://www.arcsynthesis.org/gltut/Illumination/Tutorial%2009.html I do not understand ...
4k views

### Basics of drawing in 2d with OpenGL 3 shaders

I am new to OpenGL 3 and graphics programming, and want to create some basic 2d graphics. I have the following scenario of how I might go about drawing a basic (but general) 2d rectangle. I'm not ...
312 views

### What is the point of this hard-coded vector when calculating luminance in glow/bloom effects?

I have looked at two different vertex shaders that calculate luminance and both use a "magic" vector that I'm not sure the meaning of the the actual values. For instance: const mediump vec3 ...
2k views

### Rotating a vector by another vector in shader

I have a terrain surface with a normal for each point on the terrain. I have a second detail normal map to be applied to the terrain. These normals are in 3-space. The Y value of both normals is ...
2k views

### 2D shader to draw representation of rotating sphere

I want to display a 3D textured sphere, and then rotate it in one direction. The direction will never change, and the camera will never move. One way is to actually create a spherical mesh, map a ...