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Better estimation of principle component. Fixes issue 120.

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This commit is contained in:
castano 2010-04-19 18:41:42 +00:00
parent 4783d5621e
commit ac5f849e91
1 changed files with 24 additions and 2 deletions
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26
src/nvtt/squish/maths.cpp
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@ -61,6 +61,22 @@ Sym3x3 ComputeWeightedCovariance( int n, Vec3 const* points, float const* weight
}
static Vec3 EstimatePrincipleComponent( Sym3x3 const& matrix )
{
Vec3 const row0(matrix[0], matrix[1], matrix[2]);
Vec3 const row1(matrix[1], matrix[3], matrix[4]);
Vec3 const row2(matrix[2], matrix[4], matrix[5]);
float r0 = Dot(row0, row0);
float r1 = Dot(row1, row1);
float r2 = Dot(row2, row2);
if (r0 > r1 && r0 > r2) return row0;
if (r1 > r2) return row1;
return row2;
}
#define POWER_ITERATION_COUNT 8
#if SQUISH_USE_SIMD
@ -70,7 +86,13 @@ Vec3 ComputePrincipleComponent( Sym3x3 const& matrix )
Vec4 const row0( matrix[0], matrix[1], matrix[2], 0.0f );
Vec4 const row1( matrix[1], matrix[3], matrix[4], 0.0f );
Vec4 const row2( matrix[2], matrix[4], matrix[5], 0.0f );
Vec4 v = VEC4_CONST( 1.0f );
//Vec4 v = VEC4_CONST( 1.0f );
//Vec4 v = row0; // row1, row2
Vec3 v3 = EstimatePrincipleComponent( matrix );
Vec4 v( v3.X(), v3.Y(), v3.Z(), 0.0f );
for( int i = 0; i < POWER_ITERATION_COUNT; ++i )
{
// matrix multiply
@ -91,7 +113,7 @@ Vec3 ComputePrincipleComponent( Sym3x3 const& matrix )
Vec3 ComputePrincipleComponent( Sym3x3 const& matrix )
{
Vec3 v(1, 1, 1);
Vec3 v = EstimatePrincipleComponent( matrix );
for (int i = 0; i < POWER_ITERATION_COUNT; i++)
{
float x = v.X() * matrix[0] + v.Y() * matrix[1] + v.Z() * matrix[2];