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#include "video/nebu_png_texture.h"
#include <stdio.h>
#include <stdlib.h>
#if !defined(WIN32) && !defined(macintosh)
#include <unistd.h>
#endif
#define ERR_PREFIX "[load_png_texture] "
#include <png.h>
FILE *f;
void user_read_data(png_structp png_ptr,
png_bytep data, png_size_t length) {
fread(data, 1, length, f);
}
png_texture* load_png_texture(char *filename) {
unsigned int i;
int bpc, color_type, zsize;
png_texture *tex;
/* the following is defined in <png.h> */
png_uint_32 x, y;
png_structp png_ptr;
png_infop info_ptr;
png_byte **row_pointers;
f = fopen(filename, "rb");
if(f == NULL) {
fprintf(stderr, ERR_PREFIX "can't open file %s\n", filename);
return NULL;
}
png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING, 0, 0, 0);
if (!png_ptr)
return NULL;
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr){
png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
return NULL;
}
/* png_init_io(png_ptr, f);
fprintf(stderr, "png, after init io \n"); */
/* I need to do this, otherwise it crashes on win32 */
png_set_read_fn(png_ptr, 0, user_read_data);
/* fprintf(stderr, "png, after init user_read_data\n"); */
png_read_info(png_ptr, info_ptr);
/* fprintf(stderr, "png, after read info \n"); */
png_get_IHDR(png_ptr, info_ptr, &x, &y, &bpc, &color_type, 0, 0, 0);
if(color_type != PNG_COLOR_TYPE_RGB &&
color_type != PNG_COLOR_TYPE_RGB_ALPHA) {
png_destroy_read_struct(&png_ptr, &info_ptr, 0);
fprintf(stderr, ERR_PREFIX "wrong png_color_type\n");
fclose(f);
return NULL;
}
if(bpc != 8) {
png_destroy_read_struct(&png_ptr, &info_ptr, 0);
fprintf(stderr, ERR_PREFIX "wrong bitdepth: %d\n", bpc);
fclose(f);
return NULL;
}
switch(color_type) {
case PNG_COLOR_TYPE_RGB: zsize = 3; break;
case PNG_COLOR_TYPE_RGB_ALPHA: zsize = 4; break;
default:
fprintf(stderr, "unknown png color type\n");
return NULL;
}
tex = (png_texture*) malloc(sizeof(png_texture));
tex->data = malloc(x * y * zsize);
tex->width = x;
tex->height = y;
tex->channels = zsize;
/* get pointers */
row_pointers = (png_byte**) malloc(y * sizeof(png_byte*));
for(i = 0; i < y; i++)
row_pointers[i] = tex->data + (y - i - 1)
* zsize * x;
png_read_image(png_ptr, row_pointers);
png_destroy_read_struct(&png_ptr, &info_ptr, 0);
free(row_pointers);
fclose(f);
return tex;
}
void unload_png_texture(png_texture *tex) {
free(tex->data);
free(tex);
}
#define TARGET(X, Y, I) (mip->data + I + mip->channels * (X + Y * mip->width))
#define SOURCE(X, Y, I) (source->data + I + \
source->channels * (X + Y * source->width))
png_texture* mipmap_png_texture(png_texture *source, int level,
int clamp_u, int clamp_v) {
png_texture *mip;
int i;
int x, y;
int fx, fy;
if(level != 1) return NULL;
mip = (png_texture*) malloc(sizeof(png_texture));
mip->channels = source->channels;
fx = (source->width > 1) ? 2 : 1;
fy = (source->height > 1) ? 2 : 1;
mip->width = source->width / fx;
mip->height = source->height / fy;
mip->data = (unsigned char*) malloc(mip->width * mip->height *
mip->channels);
/* simple linear filtering */
for(i = 0; i < mip->channels; i++) {
for(y = 0; y < mip->height; y++) {
for(x = 0; x < mip->width; x++) {
/*
*( TARGET(x, y, i) ) = ( *( SOURCE(x * fx, y * fy, i) ) +
*( SOURCE((x + 1) * fx, (y + 1) * fy, i) ) +
*( SOURCE((x + 1) * fx, y * fy, i) ) +
*( SOURCE(x * fx, (y + 1) * fy, i) ) ) / 4;
*/
int sx, sy, xoff, yoff;
sx = fx * x;
sy = fy * y;
xoff = fx - 1;
yoff = fy - 1;
*( mip->data + i + mip->channels * ( x + y * mip->width ) ) =
( *( source->data + i + source->channels * ( sx + sy * source->width) ) +
*( source->data + i + source->channels * ( sx + xoff + sy * source->width) ) +
*( source->data + i + source->channels * ( sx + xoff + (sy + yoff) * source->width) ) +
*( source->data + i + source->channels * ( sx + (sy + yoff) * source->width) ) ) / 4;
}
}
}
return mip;
}
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