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tweak baldurk's hdr implementation

This commit is contained in:
Sean Barrett 2015-01-17 07:46:22 -08:00
parent 258fb15340
commit edd5e6700d
1 changed files with 39 additions and 20 deletions
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51
stb_image_write.h
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@ -1,16 +1,16 @@
/* stb_image_write - v0.95 - public domain - http://nothings.org/stb/stb_image_write.h
/* stb_image_write - v0.96 - public domain - http://nothings.org/stb/stb_image_write.h
writes out PNG/BMP/TGA images to C stdio - Sean Barrett 2010
no warranty implied; use at your own risk
Before including,
Before #including,
#define STB_IMAGE_WRITE_IMPLEMENTATION
in the file that you want to have the implementation.
in the file that you want to have the implementation.
Will probably not work correctly with strict-aliasing optimizations.
Will probably not work correctly with strict-aliasing optimizations.
ABOUT:
@ -56,6 +56,17 @@ USAGE:
HDR expects linear float data. Since the format is always 32-bit rgb(e)
data, alpha (if provided) is discarded, and for monochrome data it is
replicated across all three channels.
CREDITS:
PNG/BMP/TGA
Sean Barrett
HDR
Baldur Karlsson
TGA monochrome:
Jean-Sebastien Guay
Bugfixes:
Chribba@github
*/
#ifndef INCLUDE_STB_IMAGE_WRITE_H
@ -68,7 +79,7 @@ extern "C" {
extern int stbi_write_png(char const *filename, int w, int h, int comp, const void *data, int stride_in_bytes);
extern int stbi_write_bmp(char const *filename, int w, int h, int comp, const void *data);
extern int stbi_write_tga(char const *filename, int w, int h, int comp, const void *data);
extern int stbi_write_hdr(char const *filename, int w, int h, int comp, const void *data);
extern int stbi_write_hdr(char const *filename, int w, int h, int comp, const float *data);
#ifdef __cplusplus
}
@ -83,6 +94,7 @@ extern int stbi_write_hdr(char const *filename, int w, int h, int comp, const vo
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <math.h>
typedef unsigned int stbiw_uint32;
typedef int stb_image_write_test[sizeof(stbiw_uint32)==4 ? 1 : -1];
@ -193,7 +205,7 @@ int stbi_write_tga(char const *filename, int x, int y, int comp, const void *dat
// *************************************************************************************************
// Radiance RGBE HDR writer
// originally by Baldur Karlsson
// by Baldur Karlsson
#define stbiw__max(a, b) ((a) > (b) ? (a) : (b))
void stbiw__linear_to_rgbe(unsigned char *rgbe, float *linear)
@ -204,7 +216,7 @@ void stbiw__linear_to_rgbe(unsigned char *rgbe, float *linear)
if (maxcomp < 1e-32) {
rgbe[0] = rgbe[1] = rgbe[2] = rgbe[3] = 0;
} else {
maxcomp = (float) frexp(maxcomp, &exponent) * 256.0f/maxcomp;
float normalize = (float) frexp(maxcomp, &exponent) * 256.0f/maxcomp;
rgbe[0] = (unsigned char)(linear[0] * maxcomp);
rgbe[1] = (unsigned char)(linear[1] * maxcomp);
@ -216,6 +228,7 @@ void stbiw__linear_to_rgbe(unsigned char *rgbe, float *linear)
void stbiw__write_rle_data(FILE *f, int length, unsigned char databyte)
{
unsigned char lengthbyte = 0x80 | (unsigned char)(length & 0x7f);
assert(length <= 0x7f);
fwrite(&lengthbyte, 1, 1, f);
fwrite(&databyte, 1, 1, f);
}
@ -223,11 +236,12 @@ void stbiw__write_rle_data(FILE *f, int length, unsigned char databyte)
void stbiw__write_nonrle_data(FILE *f, int length, unsigned char *data)
{
unsigned char lengthbyte = (unsigned char )(length & 0xff);
assert(length <= 0x7f);
fwrite(&lengthbyte, 1, 1, f);
fwrite(data, length, 1, f);
}
void stbiw__write_hdr_scanline(FILE *f, int width, int comp, unsigned char *scratch, float *scanline)
void stbiw__write_hdr_scanline(FILE *f, int width, int comp, unsigned char *scratch, const float *scanline)
{
unsigned char scanlineheader[4] = { 2, 2, 0, 0 };
unsigned char rgbe[4];
@ -324,26 +338,28 @@ void stbiw__write_hdr_scanline(FILE *f, int width, int comp, unsigned char *scra
}
}
int stbi_write_hdr(char const *filename, int x, int y, int comp, const void *data)
int stbi_write_hdr(char const *filename, int x, int y, int comp, const float *data)
{
int i;
FILE *f;
unsigned char *scratch;
if (y <= 0 || x <= 0) return 0;
if (y <= 0 || x <= 0 || data == NULL) return 0;
f = fopen(filename, "wb");
if (f) {
float *scanline = (float *)data;
/* Each component is stored separately. Allocate scratch space for full output scanline. */
scratch = (unsigned char *) malloc(x*4); if (!scanline) { fclose(f); return 0; }
fprintf(f, "#?RADIANCE\n# Written by stb_image_write.h\nFORMAT=32-bit_rle_rgbe\n");
fprintf(f, "EXPOSURE= 1.0000000000000\n\n-Y %d +X %d\n", y, x);
for(i=0; i < y; i++) stbiw__write_hdr_scanline(f, x, comp, scratch, scanline + comp*i*x);
unsigned char *scratch = (unsigned char *) malloc(x*4);
fprintf(f, "#?RADIANCE\n# Written by stb_image_write.h\nFORMAT=32-bit_rle_rgbe\n" );
fprintf(f, "EXPOSURE= 1.0000000000000\n\n-Y %d +X %d\n" , y, x);
for(i=0; i < y; i++)
stbiw__write_hdr_scanline(f, x, comp, scratch, data + comp*i*x);
free(scratch);
fclose(f);
}
return f != NULL;
}
/////////////////////////////////////////////////////////
// PNG
// stretchy buffer; stbiw__sbpush() == vector<>::push_back() -- stbiw__sbcount() == vector<>::size()
#define stbiw__sbraw(a) ((int *) (a) - 2)
#define stbiw__sbm(a) stbiw__sbraw(a)[0]
@ -666,6 +682,9 @@ int stbi_write_png(char const *filename, int x, int y, int comp, const void *dat
/* Revision history
0.96 (2015-01-17)
add HDR output
fix monochrome BMP
0.95 (2014-08-17)
add monochrome TGA output
0.94 (2014-05-31)