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#include "render.h"
#include <stdio.h>
#include <stdlib.h>
typedef struct {
float r, g, b;
} vec3;
typedef struct {
vec3 start, end;
unsigned char indices[4 * 4];
} Block;
void get_block(Block* block, Colour* pixels, int stride) {
int x, y, i;
vec3 cols[4 * 4];
vec3 s, e;
float cd;
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
Colour pixel = pixels[x + y * stride];
vec3 vec;
vec.r = (float)pixel.r / 255.0f;
vec.g = (float)pixel.g / 255.0f;
vec.b = (float)pixel.b / 255.0f;
cols[x + y * 4] = vec;
}
}
cd = -1.0f;
for (i = 0; i < 4 * 4; i++) {
int j;
vec3* a = &cols[i];
for (j = i + 1; j < 4 * 4; j++) {
vec3* b = &cols[j];
float d =
(b->r - a->r) * (b->r - a->r) +
(b->g - a->g) * (b->g - a->g) +
(b->b - a->b) * (b->b - a->b);
if (d > cd) {
cd = d;
s = *a;
e = *b;
}
}
}
for (i = 0; i < 4 * 4; i++) {
vec3* col = &cols[i];
float d;
d =
(e.r - col->r) * (e.r - col->r) +
(e.g - col->g) * (e.g - col->g) +
(e.b - col->b) * (e.b - col->b);
if (cd < 0.0001f)
block->indices[i] = 0;
else {
d = d / cd;
block->indices[i] = (int)((1.0f - d) * 3.1f);
}
}
block->start = s;
block->end = e;
}
void compress_block(const Block* block, FILE* f) {
int i;
unsigned start =
((unsigned)(block->start.r * 31.9999f) << 11) |
((unsigned)(block->start.g * 63.9999f) << 5) |
((unsigned)(block->start.b * 31.9999f));
unsigned end =
((unsigned)(block->end.r * 31.9999f) << 11) |
((unsigned)(block->end.g * 63.9999f) << 5) |
((unsigned)(block->end.b * 31.9999f));
unsigned palette = (start << 16) | end;
unsigned indices = 0;
fwrite(&palette, 1, 4, f);
for (i = 0; i < 4 * 4; i++) {
indices |= block->indices[i] << (i * 2);
}
fwrite(&indices, 1, 4, f);
}
void compress_bc1(Colour* pixels, int w, int h, FILE* f) {
int x, y, cw, ch;
Block block;
fwrite(&w, 1, 4, f);
fwrite(&h, 1, 4, f);
cw = w / 4;
ch = h / 4;
for (y = 0; y < ch; y++) {
for (x = 0; x < cw; x++) {
get_block(&block, &pixels[x * 4 + y * 4 * w], w);
compress_block(&block, f);
}
}
}
int main(int argc, const char** argv) {
FILE* outfile, * infile;
char bmp_magic[2];
unsigned bmp_offset;
int bmp_w, bmp_h, s, x, y;
unsigned short bmp_bits;
Colour* buffer;
Colour pixel;
if (argc < 3) {
fprintf(stderr, "Usage: %s infile outfile.\n", argv[0]);
return 1;
}
infile = fopen(argv[1], "rb");
if (!infile) {
fprintf(stderr, "Failed to open %s.\n", argv[1]);
return 2;
}
fread(bmp_magic, 2, 1, infile);
if (bmp_magic[0] != 'B' || bmp_magic[1] != 'M') {
fprintf(stderr, "Not a valid bitmap file.\n");
return 3;
}
fseek(infile, 10, SEEK_SET);
fread(&bmp_offset, 4, 1, infile);
fseek(infile, 18, SEEK_SET);
fread(&bmp_w, 4, 1, infile);
fread(&bmp_h, 4, 1, infile);
fseek(infile, 28, SEEK_SET);
fread(&bmp_bits, 2, 1, infile);
if (bmp_bits != 32) {
fprintf(stderr, "Bitmap must have 32 bit pixels. Instead has %d bit pixels.\n", bmp_bits);
return 4;
}
if (bmp_w % 4 != 0 || bmp_h % 4 != 0) {
fprintf(stderr, "Bitmap must have a size divisible by four.\n");
return 5;
}
fseek(infile, bmp_offset, SEEK_SET);
s = bmp_w * bmp_h;
buffer = malloc(s * 4);
/* Flip & read. */
for (y = 0; y < bmp_h; y++) {
for (x = 0; x < bmp_w; x++) {
unsigned char t;
fread(&pixel, 1, 4, infile);
t = pixel.r;
pixel.r = pixel.b;
pixel.b = t;
if (pixel.a == 0) {
pixel.r = 0;
pixel.g = 0;
pixel.b = 0;
}
buffer[x + (bmp_h - y - 1) * bmp_w] = pixel;
}
}
outfile = fopen(argv[2], "wb");
if (!outfile) {
fprintf(stderr, "Failed to open %s.\n", argv[2]);
return 6;
}
compress_bc1(buffer, bmp_w, bmp_h, outfile);
fclose(outfile);
return 0;
}
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