Yours3!f

Hi,

is there any way to prevent OGL to write the depth buffer from the fragment shader? I'm thinking of something like discard.

I'd like to throw away pixels whose alpha is not big enough. This would help me to perform early depth testing to reduce overdraw.

Node that this is a 2D engine, so all of this are basically sprites.

Best regards,

Yours3lf

Hi,

I'm trying out the OpenGL compute shader functionality using the new Catalyst 13.4 driver from AMD.

However when I execute the compute shader the driver restarts.

I used this example as a basis: http://wili.cc/blog/opengl-cs.html

here's the project:
https://docs.google.com/file/d/0B33Sh832pOdOaWFlVS00N040bFE/edit?usp=sharing
 

any idea what may be wrong?

Best regards,

Yours3!f

Hi,

I've implemented the "screen space soft shadows" technique (in OGL):

[Gumbau] Jesus Gumbau, Miguel Chover, and Mateu Sbert, “Screen-Space Soft Shadows”, GPU Pro, pp. 477 – 490

The shadow looks nice and soft, however making the shadow soft didn't remove the blockiness. I found out that this can be reduced by increasing the shadow map size from  1024 to 2048 ( and so on ), but this kills performance, and memory bandwith. Is there some kind of filtering technique that can reduce this basic blocky property of shadow mapping? So that soft shadows can really look soft. Not blocky soft

I've attached a picture with soft shadows turned up, and of the simple shadow map.

Best regards,

Yours3lf

Hi,

I'm writing a cpu raytracer using my math library based on this tutorial:

http://www.flipcode.com/archives/Raytracing_Topics_Techniques-Part_1_Introduction.shtml

I got through it up to chapter 6, where I noticed that I get subtle artifacts in the rendering (see pic), which gets even more pronounced when I enable fast mode (only diffuse lighting, 3 fps).

Any idea what am I doing wrong?

download here:

https://docs.google.com/file/d/0B33Sh832pOdOaE1LU3ZqMWZBUzQ/edit?usp=sharing

EDIT: to run the exe on linux, set the LD_LIBRARY_PATH to ../external/lib, ../external/lib/tbb

you'll also need to create a symlink from external/lib/libGLEW.so to libGLEW.so.1.6 (for some reason it links to libGLEW.so.1.6 too... even though I have 1.7)

you'll also need to install gsl (GNU scientific lib)

you can also build it using cmake. To disable the tbb (Intel thread building blocks) and gsl dependencies, set in globals.h USE_QRNG to 0, and COUNT_INTERSECTIONS to 1. Make sure you're not linking to it after this. Note that this will disable threading and usage of quasi random numbers.

Best regards,

Yours3lf

Hi,

I'd like to pack a float and two booleans into a rgba8 texture.

Unfortunately I don't really know how to do this

The way I imagined this is:

break up the bits of the float in 3 parts, store them in rgb, so they'd get 24 bits precision

store the two booleans in the a channel somehow...

any ideas how to do this?

best regards,

Yours3lf