fix BC1 compressor

1 files changed, 82 insertions, 0 deletions

diff --git a/testbc1.c b/testbc1.c
new file mode 100644
index 0000000..1ae5a3e
--- /dev/null
+++ b/testbc1.c
@@ -0,0 +1,82 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct {
+	unsigned char r, g, b, a;
+} Colour;
+
+typedef struct {
+	float r, g, b;
+} vec3;
+
+void lerp(vec3* d, const vec3* a, const vec3* b, float t) {
+	d->r = a->r + t * (b->r - a->r);
+	d->g = a->g + t * (b->g - a->g);
+	d->b = a->b + t * (b->b - a->b);
+}
+
+Colour get_pixel(unsigned* data, int x, int y, int w) {
+	vec3 c[4];
+	float t;
+	int i;
+	Colour r = { 0 };
+	unsigned palette = data[(x / 4 + y / 4 * (w / 4)) * 2];
+	unsigned indices = data[(x / 4 + y / 4 * (w / 4)) * 2 + 1];
+	c[0].r = (float)((palette & (31 << 11)) >> 11) / 32.0f;
+	c[0].g = (float)((palette & (63 << 5))  >> 5)  / 64.0f;
+	c[0].b = (float)((palette & (31     ))      )  / 32.0f;
+	c[1].r   = (float)((palette & (31 << 27)) >> 27) / 32.0f;
+	c[1].g   = (float)((palette & (63 << 21)) >> 21) / 64.0f;
+	c[1].b   = (float)((palette & (31 << 16)) >> 16) / 32.0f;
+	c[2].r = 2.0f/3.0f*c[0].r + 1.0f/3.0f*c[1].r;
+	c[2].g = 2.0f/3.0f*c[0].g + 1.0f/3.0f*c[1].g;
+	c[2].b = 2.0f/3.0f*c[0].b + 1.0f/3.0f*c[1].b;
+	c[3].r = 1.0f/3.0f*c[0].r + 2.0f/3.0f*c[1].r;
+	c[3].g = 1.0f/3.0f*c[0].g + 2.0f/3.0f*c[1].g;
+	c[3].b = 1.0f/3.0f*c[0].b + 2.0f/3.0f*c[1].b;
+	i = x % 4 + (y % 4) * 4;
+	i = (indices & (3 << i * 2)) >> i * 2;
+	r.r = (int)(c[i].r * 255.0f);
+	r.g = (int)(c[i].g * 255.0f);
+	r.b = (int)(c[i].b * 255.0f);
+	return r;
+}
+
+int main(int argc, const char** argv) {
+	FILE* infile, * outfile;
+	unsigned* data;
+	int w, h, x, y, cw, ch;
+	unsigned palette, indices;
+	vec3 colour;
+	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;
+	}
+	outfile = fopen(argv[2], "w");
+	if (!infile) {
+		fprintf(stderr, "Failed to open %s.\n", argv[2]);
+		return 3;
+	}
+	fseek(infile, 4, SEEK_SET);
+	fread(&w, 1, 4, infile);
+	fread(&h, 1, 4, infile);
+	fseek(infile, 4, SEEK_CUR);
+	cw = w / 4;
+	ch = h / 4;
+	data = malloc(cw * ch * 8);
+	fread(data, 1, cw * ch * 8, infile);
+	fprintf(outfile, "P3\n");
+	fprintf(outfile, "%d %d\n", w, h);
+	fprintf(outfile, "255\n");
+	for (y = 0; y < h; y++) {
+		for (x = 0; x < w; x++) {
+			Colour c = get_pixel(data, x, y, w);
+			fprintf(outfile, "%d %d %d\n", c.r, c.g, c.b);
+		}
+	}
+}