diff options
Diffstat (limited to 'nebu/video/png_texture.c')
| -rw-r--r-- | nebu/video/png_texture.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/nebu/video/png_texture.c b/nebu/video/png_texture.c new file mode 100644 index 0000000..0721523 --- /dev/null +++ b/nebu/video/png_texture.c @@ -0,0 +1,157 @@ +#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; +} |