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Update seed_rng() in stdlib to take a varying seed.

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Previously, we were trying to take a uniform seed and then shuffle that
around to initialize the state for each of the program instances.  This
was becoming increasingly untenable and brittle.

Now a varying seed is expected and used.
This commit is contained in:
Matt Pharr
2012-05-30 10:35:41 -07:00
parent 5cb53f52c3
commit 8fd9b84a80
6 changed files with 11 additions and 58 deletions
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2
examples/aobench/ao.ispc
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@@ -210,7 +210,7 @@ static void ao_scanlines(uniform int y0, uniform int y1, uniform int w,
{ { 1.0f, 0.0f, -2.2f }, 0.5f } };
RNGState rngstate;
seed_rng(&rngstate, y0);
seed_rng(&rngstate, programIndex + (y0 << (programIndex & 15)));
float invSamples = 1.f / nsubsamples;
foreach_tiled(y = y0 ... y1, x = 0 ... w,

2
examples/aobench_instrumented/ao.ispc
View File

@@ -211,7 +211,7 @@ static void ao_scanlines(uniform int y0, uniform int y1, uniform int w,
{ { 1.0f, 0.0f, -2.2f }, 0.5f } };
RNGState rngstate;
seed_rng(&rngstate, y0);
seed_rng(&rngstate, programIndex + (y0 << (programIndex & 15)));
// Compute the mapping between the 'programCount'-wide program
// instances running in parallel and samples in the image.