Particle Engine, Creating alot of Rain/Snow

Medo Mex · 2012-06-09T02:26:39

I have created a particle engine, basically, it create ONE single vertex using CreateVertexBuffer() and rendering it as much as particles we need. Using the class I assign the number of particles that I want to generate at once, I am using "for() { }" statement to generate that number each time like the following: void RenderParticles(...) { // Some other codes goes here... for(DWORD i = 0; i < maxNumOfParticles; i++) CreateNewParticle(); } When I create a rain usually I set a high number for maxNumOfParticles number like 150-250, so I can have alot of rains rendering (if the weather is so rainy). However, the rendering SLOW down when 'maxNumOfParticles' is high, making the game slow even on a modern graphic card.

Graphics and GPU Programming Programming

Started by Medo Mex June 08, 2012 02:20 AM

11 comments, last by jefferytitan 11 years, 10 months ago

Medo Mex

891

Author

June 08, 2012 09:24 PM

@DJNT: I am using point sprites (billboarding) each vertex contains one texture.

21st Century Moose

13,459

June 08, 2012 11:51 PM

I personally use one vertex (containing initial position, velocity, gravity factors, acceleration, time-since-spawn, etc) with forward/left/up values as shader constants, combined with instancing - everything is computed on the GPU from there and up to 16384 (arbitrary choice) particles are drawn per draw-call. There's no need whatsoever for any matrix changes and it runs faster than a slippery snot on a slope.

Again - show some more code, and how many draw calls?

Direct3D has need of instancing, but we do not. We have plenty of glVertexAttrib calls.

jefferytitan

2,525

June 09, 2012 02:26 AM

I think the other posters are on the same page as me. You may be making savings on the CPU by using a single vertex, but you're punishing the GPU by making many separate draw calls. It would probably run better if you had 200 vertices but pushed them through in a single batch.

Particle Engine, Creating alot of Rain/Snow

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Particle Engine, Creating alot of Rain/Snow

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