fix BC1 compressor

3 files changed, 138 insertions, 22 deletions

diff --git a/convtexture.c b/convtexture.c
index a04e3c9..2670b59 100644
--- a/convtexture.c
+++ b/convtexture.c
@@ -29,10 +29,19 @@ const char* format_names[] = {
 #undef x
 };
 
+unsigned encode_endpoint(const vec3* v) {
+	return
+		((unsigned)(v->r * 31.9999f) << 11) |
+		((unsigned)(v->g * 63.9999f) << 5) |
+		((unsigned)(v->b * 31.9999f));
+}
+
 void get_block(Block* block, Colour* pixels, int stride) {
 	int x, y, i;
 	vec3 cols[4 * 4];
+	vec3 palette[3];
 	vec3 s, e;
+	unsigned es, ee;
 	float cd;
 	for (y = 0; y < 4; y++) {
 		for (x = 0; x < 4; x++) {
@@ -61,19 +70,48 @@ void get_block(Block* block, Colour* pixels, int stride) {
 			}
 		}
 	}
+	es = encode_endpoint(&s);
+	ee = encode_endpoint(&e);
+	if (es == ee) {
+		block->start = s;
+		block->end.r = 0.0f;
+		block->end.g = 0.0f;
+		block->end.b = 0.0f;
+		for (i = 0; i < 16; i++) {
+			block->indices[i] = 0;
+		}
+		return;
+	}
+	if (es < ee) {
+		/* todo alpha */
+		vec3 t = s;
+		s = e;
+		e = t;
+	}
+	palette[0] = s;
+	palette[1] = e;
+	palette[2].r = 0.666666f*palette[0].r + 0.333333f*palette[1].r;
+	palette[2].g = 0.666666f*palette[0].g + 0.333333f*palette[1].g;
+	palette[2].b = 0.666666f*palette[0].b + 0.333333f*palette[1].b;
+	palette[3].r = 0.333333f*palette[0].r + 0.666666f*palette[1].r;
+	palette[3].g = 0.333333f*palette[0].g + 0.666666f*palette[1].g;
+	palette[3].b = 0.333333f*palette[0].b + 0.666666f*palette[1].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);
+		int closest = 0, j;
+		float cd = 99999.0f;
+		for (j = 0; j < 4; j++) {
+			vec3* p = &palette[j];
+			float d =
+				(p->r - col->r) * (p->r - col->r) +
+				(p->g - col->g) * (p->g - col->g) +
+				(p->b - col->b) * (p->b - col->b);
+			if (d < cd) {
+				cd = d;
+				closest = j;
+			}
 		}
+		block->indices[i] = closest;
 	}
 	block->start = s;
 	block->end = e;
@@ -81,19 +119,15 @@ void get_block(Block* block, Colour* pixels, int stride) {
 
 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 start = encode_endpoint(&block->start);
+	unsigned end   = encode_endpoint(&block->end);
 	unsigned indices = 0;
-	fwrite(&palette, 1, 4, f);
+	fwrite(&start, 1, 2, f);
+	fwrite(&end,   1, 2, f);
 	for (i = 0; i < 4 * 4; i++) {
-		indices |= block->indices[i] << (i * 2);
+		int idx = (4 * 4 - 1) - i;
+		idx = i;
+		indices |= block->indices[i] << (idx * 2);
 	}
 	fwrite(&indices, 1, 4, f);
 }
diff --git a/intermediate/triangle.glsl b/intermediate/triangle.glsl
index beee129..8f3b586 100644
--- a/intermediate/triangle.glsl
+++ b/intermediate/triangle.glsl
@@ -49,7 +49,7 @@ void main() {
 
 void main() {
 	vec3 c = texture(colour_texture, interpolator.uv).rgb;
-//	c *= interpolator.colour;
+	c *= interpolator.colour;
 	colour = vec4(c, 1.0);
 }
 
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);
+		}
+	}
+}