GPU Pro 7

3. Deferred Attribute Interpolation Shading 93

1 #e x t e n si on GL NV shader thread group : e nable

2 uint sid =0; // Shading sample address

3 if (( gl_ThreadInWarpNV &3)==0) // One thread allocates memory.

4 sid = atomicCounterIncrement ( ctr_shading_samples );

5 // Communicate to all invocations .

6 uint sid_sw = floatBitsToUint (

7 quadSwizzle0NV ( uintBitsToFloat( sid )));

8 if ( sid_sw == 0 ) { // Fails when there are helper−invocations .

9 if( sid == 0 ) // Allocate shading samples for all invocations .

10 sid = atomicCounterIncrement ( ctr_shading_samples );

11 store_shading_sample ( sid );

12 } else if (( gl_ThreadInWarpNV &0x03)==0) {

13 sid