0
votes
1answer
77 views

Blending and shadowmapping?

I am trying to implement shadow mapping, and currently I have 2 point lights and 1 global ambient light source and my rendering loop looks roughly like this (the details are not relevant): void ...
2
votes
3answers
668 views

OpenGL additive blending not working as expected

I am trying to achieve additive blending with point sprites. When the sprites overlap, all I get is solid red, when I expect to get a smooth blend from red->yellow->white. My sprite texture has all ...
1
vote
0answers
86 views

How to put OpenGL in a state for drawing blended, colored, nontextured polys?

Using OpenGL1.1 (sadly) I'm trying to draw a cube, which is colored and alpha blended. It is instead showing up as opaque black. Even without including alpha in the color it still shows up as opaque ...
5
votes
1answer
372 views

What are the rest of the blending functions used for?

In general, I know of five ways to make use of blending functions (these are for OpenGL, but replace glBlendFunc() with SetRenderState(D3DRS_SRCBLEND) and SetRenderState(D3DRS_DESTBLEND) for DirectX): ...
1
vote
1answer
147 views

Artifacts when draw particles with some alpha

I want to draw in my game some particles. But when I draw one particle above another particle, alpha channel from this above "clear" previous drawed particle. I set in OpenGL blend in this way: ...
0
votes
1answer
224 views

Rendering two textures with blending and alpha test

What I am looking for is the following: I have a circle on a square image, alpha is 0 at the corners and also a square shadow, alpha is 0 everywhere else I would like to have as final result a ...
2
votes
1answer
1k views

Understanding how OpenGL blending works

I am attempting to understand how OpenGL (ES) blending works. I am finding it difficult to understand the documentation and how the results of glBlendFunc and glBlendEquation effect the final pixel ...
2
votes
0answers
372 views

AlphaToCoverage + Alpha Blending = Artifacts

I'm experiencing a strange problem using OpenGL SampleAlphaToCoverage mode. There are rendering artifacts when using alpha-blending on pixels that have been rendered using alpha-to-coverage - and I ...
26
votes
5answers
7k views

How can I achieve a good fire effect with alpha blending and particles?

Using the following setting for the OpenGL particle effect: SRC: GL_SRC_ALPHA DST: GL_ONE Creates an additive blend, which looks spectacular on a black background but terrible on brighter colours, ...
1
vote
1answer
541 views

How can I implement “cut outs” for lighting in OpenGL?

So, I'm working with OpenGL (I'm not exactly sure of the version), and I want to do an old-style lighting setup by essentially drawing a black rectangle over the screen, and drawing white circles over ...
3
votes
2answers
1k views

blending alpha textures in gluOrtho2D

i'm doing a simple game/application with some minimal 2d graphics: png textures and ploygons with standard glVertex calls my setting: glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0, w, ...
9
votes
2answers
5k views

How do I use depth testing and texture transparency together in my 2.5D world?

Note: I've already found an answer (which I will post after this question) - I was just wondering if I was doing it right, or if there is a better way. I'm making a "2.5D" isometric game using OpenGL ...
4
votes
2answers
1k views

Blending 2d images to subtract alpha

I'm looking into doing a 2d lighting system with a result similar to this: http://forums.tigsource.com/index.php?topic=15619.0 This thread I believe disregards color, as well as doesn't really list a ...