problem using particles

Graphics and GPU Programming Programming

Started by _ralph July 19, 2000 03:02 PM

5 comments, last by _ralph 23 years, 9 months ago

122

Author

July 19, 2000 03:02 PM

hi I´ve tried to implement some particle effects in my OGL based landscape engine using additive blending. Therefore I have to disable GL_DEPTH_TEST but as a result of this the particles either appear in front of the scenery or totally behind depending on when they are drawn -> whether before the landscape or after. Does anyone know a sollution for that ? thanks in advance ralph

WitchLord

4,834

July 19, 2000 11:24 PM

You shouldn''t disable GL_DEPTH_TEST. You should disable depth buffer writes. And then draw the particles after drawing the landscape.

- WitchLord

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Anonymous

July 20, 2000 10:24 AM

hi

First of all thanks for your reply but I still can´t get it.
-In order to get additive blending working properly, I have to disable GL_DEPTH_TEST, haven´t I ?
-How can I disable depth buffer writes ?

ralph

max621

139

July 20, 2000 02:45 PM

I''m not sure what additive blending is... (GL_SOURCE_ALPHA and GL_ONE ??) but what I do is I just render the particles as a triangle strip for each one that is put together like a quad. And than I just make them in 3d... I think it would even be better if you make them in 3d.. yeah..

||--------------------------||Black Hole Productionshttp://bhp.nydus.netResident expert on stuffmax621@barrysworld.com||--------------------------||

zedzeek

529

July 20, 2000 05:53 PM

glDepthMask(FALSE);

Captain Courgette, eat more veg

WitchLord

4,834

July 21, 2000 04:15 AM

No, you don''t want to disable GL_DEPTH_TEST, because then your particles would be seen through solid polygons in your world, for example walls.

I believe I know why you think you need to disable the test, because otherwise the particles aren''t rendered correctly. Well, you will fix this by disabling Depth buffer writing instead. This way the particles wont be seen through solid polygons but will blend nicely with each other.

I don''t know how to disable the depth buffer writes though. Maybe zedzeek''s way will work. If it doesn''t I could probably find out for you.

- WitchLord

AngelCode.com - game development and more - Reference DB - game developer references
AngelScript - free scripting library - BMFont - free bitmap font generator - Tower - free puzzle game