20 lines
838 B
C
20 lines
838 B
C
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//========== Copyright (c) Valve Corporation, All rights reserved. ==========//
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// derivative of catmull rom spline courtesy of calc
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float4 DCatmullRomSpline ( float4 a, float4 b, float4 c, float4 d, float t )
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{
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return 0.5 *( c - a + t * ( 2 * a - 5 * b + 4 * c - d + t * (3 * b - a - 3 * c + d ) )
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+ t * ( 2 * a - 5 * b + 4 * c - d + 2 * ( t * ( 3 * b - a - 3 * c + d ) ) ) );
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}
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float3 DCatmullRomSpline3 ( float3 a, float3 b, float3 c, float3 d, float t )
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{
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return 0.5 *( c - a + t * ( 2 * a - 5 * b + 4 * c - d + t * (3 * b - a - 3 * c + d ) )
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+ t * ( 2 * a - 5 * b + 4 * c - d + 2 * ( t * ( 3 * b - a - 3 * c + d ) ) ) );
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}
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float4 CatmullRomSpline( float4 a, float4 b, float4 c, float4 d, float t )
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{
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return b + 0.5 * t * ( c - a + t * ( 2 * a - 5 * b + 4 * c - d + t * ( -a + 3 * b -3 * c + d ) ) );
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}
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