63 lines
2.1 KiB
C++
63 lines
2.1 KiB
C++
/* THIS CODE CARRIES NO GUARANTEE OF USABILITY OR FITNESS FOR ANY PURPOSE.
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* WHILE THE AUTHORS HAVE TRIED TO ENSURE THE PROGRAM WORKS CORRECTLY,
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* IT IS STRICTLY USE AT YOUR OWN RISK. */
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/* This file contains code to read and write four byte rgbe file format
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developed by Greg Ward. It handles the conversions between rgbe and
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pixels consisting of floats. The data is assumed to be an array of floats.
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By default there are three floats per pixel in the order red, green, blue.
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(RGBE_DATA_??? values control this.) Only the mimimal header reading and
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writing is implemented. Each routine does error checking and will return
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a status value as defined below. This code is intended as a skeleton so
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feel free to modify it to suit your needs.
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(Place notice here if you modified the code.)
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posted to http://www.graphics.cornell.edu/~bjw/
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written by Bruce Walter (bjw@graphics.cornell.edu) 5/26/95
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based on code written by Greg Ward
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*/
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#include <glm/glm.hpp>
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#include "rgbe.hpp"
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using glm::frexp;
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using glm::ldexp;
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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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