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Member Since 17 Dec 2009
Offline Last Active Jun 07 2012 02:12 AM

Topics I've Started

use depth from MSAA buffer in a non MSAA buffer

07 June 2012 - 02:11 AM


I have a situation where my forward scene requires a lot of alpha blending that is going to be dead slow in my MSAA buffer. So i was thinking about rendering the sampler heavy stuff (alpha) in one non multisampled buffer and blend this final result over my final scene. The question is, how can i use the depth buffer from the MSAA scene for depth tests in my non-MSAA render batches?


Scale bezier curve along normal

07 May 2012 - 04:37 AM


I want to resize a bezier curve along its normals in order to resize a free form shape. I want to resize the object, but not _scale_ it.

What i do right now is the following:

Take the set of control points
Calculate the normal on the tangent points
Add normal * size to the control points

Of course, this doesn't work exactly as it should. The tangents should be changed, but i don't know how. Right now, my shape (that is tesselated later) looks like it is liquified :)

Any idea?

My control point setup gives me a point, and a tangent in, and tangent out value (defining the other 2 control points). But if i add the normal to these points, they get eased out, as they are handled as tangents and the original point is already translated. I hope you can follow me...

I also tried to tesselate first and move every vertex along its vertex normal, but this gives me intersections pretty soon.

Thank you very much, any help is appreciated and i am happy to share a working solution as soon as i get there...


OpenGL Driver Version and Settings - how to read them?

22 February 2010 - 11:59 PM

Hi! I want to dump driver version and settings (e.g. AA, VSync, TripBuff etc, all states) - any idea how? I assume there must be extensions for that, as it is highly vendor/driver specific stuff. Can you help me? Thanks :)

cloud rendering - infinite horizon - touching the ground

03 February 2010 - 01:48 AM

hey, i'm working on a cloud system. shading, performance everything works well. i'm just stuck on the "infinite horizon" problem. as the whole scenery is almost flat, i need to render the clouds up to the maximum scene visibility, which is, by default, 170km. That's way too much for my cloud system. My current system can handle clouds up to 8.5km with high precision. normally, you would fake this by applying distance fog. i can't do this because, as said, of the high visibility that need to be provided. in real world, clouds are touching the ground in far distance. this is due to the fact of perspective and earth bending. i used this fact to simply move the clouds down to the bottom in distance. this fake looks pretty good. i just apply a factor to the cloud particle.y value based on the distance to the viewer. Now i have the following problem: if i apply this bending fake, my cloud altitude is changed. due to my application, i need to provide a correct cloud base, even in distance. This is where my depth test fails badly (hills, spaceship, etc) i tried to adjust the fragment depth value in order to avoid this problem, but this doesn't work out. or i'm too stupid to calculate the correct value. how to calculate this value? any other ideas? my depth value adjusting idea goes like this: 1. calculate the depth of the fragment without having the bending fake applied 2. apply bending fake 3. do projection etc 4. write the manual frag depth in the shader thanks! thomas thanks :)

sharing depth buffers / cloud depth question

17 December 2009 - 09:24 PM

hi, i'm going to implement volumetric clouds in my game engine. as i am going to render single clouds, scattered stuff and overcast situations with the same implementation, i was going to think about having one lowres fbo imposter for the background and render the clouds in the foreground just straight forward. so far so good, looks awesome and such, i just have 2 questions: 1) i have my main screen content directly rendered (so no fbo) - how can i use this depth information in my fbo? (as depth attachment?) or should i render the main scene in another fbo and simply use the same depth renderbuffer attachment for both fbos? does this work? 2) my clouds should touch the horizon in the lowres fbo, so i was thinking about applying a bend factor to the cloud particle.y coordinate. if i do this, my depth gets of course changed. but i need to keep the same cloud altitude for my mountains disappearing in the clouds at the right height. i know that the depth value can be changed (fragcoord.w?) - how can i change this correctly in my glsl shader? thanks in advance! :)