From ef3a460ec41af11278c1a4bd6021f610e8423e59 Mon Sep 17 00:00:00 2001 From: Jorge Rodriguez Date: Sun, 27 Jul 2014 00:55:47 -0700 Subject: [PATCH] Some better looking horners save another multiplication. --- stb_resample.h | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/stb_resample.h b/stb_resample.h index 113c6cf..e577f0f 100644 --- a/stb_resample.h +++ b/stb_resample.h @@ -279,12 +279,10 @@ static float stbr__filter_bicubic(float x) { x = (float)fabs(x); - float xx = x*x; - if (x < 1.0f) - return 0.5f * (x * xx) - xx + 0.66666666666f; + return 0.66666666666f + x*x*(0.5f*x - 1); else if (x < 2.0f) - return -0.16666666f * (x * xx) + xx - 2 * x + 1.3333333333f; + return 1.3333333333f + x*(-2 + x*(1 - 0.16666666f * x)); return (0.0f); } @@ -293,12 +291,10 @@ static float stbr__filter_catmullrom(float x) { x = (float)fabs(x); - float xx = x*x; - if (x < 1.0f) - return 1.5f * xx * (x - 1.66666666f) + 1; + return 1 - x*x*(1.5f - 2.5f*x); else if (x < 2.0f) - return -0.5f * x * ((xx - 5 * x) + 8) + 2; + return 2 - x*(4 + x*(0.5f*x - 2.5f)); return (0.0f); } @@ -307,12 +303,10 @@ static float stbr__filter_mitchell(float x) { x = (float)fabs(x); - float xx = x*x; - if (x < 1.0f) - return 1.1666666666666f * xx * (x - 1.714285715f) + 0.8888888888f; + return 0.8888888888f + x*x*(1.1666666666666f * x - 2.0f); else if (x < 2.0f) - return -0.3888888888f * x * ((xx - 5.14285714f * x) + 8.571428571f) + 1.777777777777f; + return 1.777777777777f + x*(-3.3333333333f + x*(2 - 0.3888888888888f*x)); return (0.0f); }