GPU Pro 6

2. Tile-Based Omnidirectional Shadows 325

for ( uint i=gl_LocalInvocationIndex ; i<groupCounter ; i+=←

LOCAL_SIZE_X )

{

lightIndexBuffer . lightIndices [ startLightIndex+i ]=

groupLightIndices [ i ];

}

}

Listing 2.2. Compute shader for generating indirect draw buffer.

For the Crytek Sponza scene with 103 meshes and 128 processed light sources,

the GPU time taken for this computation task was about 0.02 ms on an NVIDIA

GeForce GTX 880 Mobile.

Finally, care must be taken to reset the atomic counters of the indirect draw

and light-index buffers at the beginning of each frame, which can be done by

using the OpenGL command

glClearBufferSubData().

2.3.3 Indirect