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0025351: Visualization - provide pseudo random number generator in OCCT ray-tracing core

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This commit is contained in:
dbp
2014-12-23 14:39:18 +03:00
committed by bugmaster
parent 51023771f9
commit 312a4043c2
3 changed files with 67 additions and 1 deletions
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46
src/Shaders/RaytraceBase.fs
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@@ -19,6 +19,11 @@ uniform vec3 uOriginRT;
//! Origin of viewing ray in right-bottom corner.
uniform vec3 uOriginRB;
//! Width of the rendering window.
uniform int uWinSizeX;
//! Height of the rendering window.
uniform int uWinSizeY;
//! Direction of viewing ray in left-top corner.
uniform vec3 uDirectLT;
//! Direction of viewing ray in left-bottom corner.
@@ -141,6 +146,47 @@ vec3 MatrixRowMultiplyDir (in vec3 v,
dot (m2.xyz, v));
}
//! 32-bit state of random number generator.
uint RandState;
// =======================================================================
// function : SeedRand
// purpose : Applies hash function by Thomas Wang to randomize seeds
// (see http://www.burtleburtle.net/bob/hash/integer.html)
// =======================================================================
void SeedRand (in int theSeed)
{
RandState = uint (int (gl_FragCoord.y) * uWinSizeX + int (gl_FragCoord.x) + theSeed);
RandState = (RandState + 0x479ab41du) + (RandState << 8);
RandState = (RandState ^ 0xe4aa10ceu) ^ (RandState >> 5);
RandState = (RandState + 0x9942f0a6u) - (RandState << 14);
RandState = (RandState ^ 0x5aedd67du) ^ (RandState >> 3);
RandState = (RandState + 0x17bea992u) + (RandState << 7);
}
// =======================================================================
// function : RandInt
// purpose : Generates integer using Xorshift algorithm by G. Marsaglia
// =======================================================================
uint RandInt()
{
RandState ^= (RandState << 13);
RandState ^= (RandState >> 17);
RandState ^= (RandState << 5);
return RandState;
}
// =======================================================================
// function : RandFloat
// purpose : Generates a random float in [0, 1) range
// =======================================================================
float RandFloat()
{
return float (RandInt()) * (1.f / 4294967296.f);
}
// =======================================================================
// function : MatrixColMultiplyPnt
// purpose : Multiplies a vector by matrix