41 lines
1.1 KiB
C++
41 lines
1.1 KiB
C++
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#include <cmath>
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#include "rgbe.hpp"
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/* standard conversion from float pixels to rgbe pixels */
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/* note: you can remove the "inline"s if your compiler complains about it */
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void float2rgbe(unsigned char rgbe[4], float red, float green, float blue) {
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float v;
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int e;
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v = red;
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if (green > v) v = green;
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if (blue > v) v = blue;
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if (v < 1e-32) {
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rgbe[0] = rgbe[1] = rgbe[2] = rgbe[3] = 0;
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}
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else {
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v = frexp(v,&e) * 256.0/v;
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rgbe[0] = (unsigned char) (red * v);
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rgbe[1] = (unsigned char) (green * v);
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rgbe[2] = (unsigned char) (blue * v);
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rgbe[3] = (unsigned char) (e + 128);
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}
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}
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/* standard conversion from rgbe to float pixels */
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/* note: Ward uses ldexp(col+0.5,exp-(128+8)). However we wanted pixels */
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/* in the range [0,1] to map back into the range [0,1]. */
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void rgbe2float(float & red, float & green, float & blue, unsigned char rgbe[4]) {
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float f;
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if (rgbe[3]) { /*nonzero pixel*/
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f = ldexp(1.0,rgbe[3]-(int)(128+8));
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red = rgbe[0] * f;
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green = rgbe[1] * f;
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blue = rgbe[2] * f;
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}
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else
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red = green = blue = 0.0;
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}
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