change the raster format to RGBA32. draw to any image format. clean up.

got rid of the bullshit dance between XRGB32 and RGBA32, now
all rasters are RGBA32 and premultiply alpha before loading
up an image and drawing over the destination. this lets the
user compose their own scenes with correct transparency.

no more mediocre clearcolor.

as a consequence drawing got slower, but if i get the turbo
drawing pool working properly that should go away.

textures also take alpha pre-multiplied channels into account,
dividing them when sampling, so loading transparent textures
will show the correct colors.

1 files changed, 7 insertions, 0 deletions

diff --git a/texture.c b/texture.c
index 5d04b89..df5089a 100644
--- a/texture.c
+++ b/texture.c
@@ -48,6 +48,7 @@ _memreadcolor(Texture *t, Point sp)
 	uchar cbuf[4];
 
 	switch(t->image->chan){
+	default: sysfatal("unsupported texture format");
 	case RGB24:
 		unloadmemimage(t->image, rectaddpt(UR, sp), cbuf+1, sizeof cbuf - 1);
 		cbuf[0] = 0xFF;
@@ -63,6 +64,12 @@ _memreadcolor(Texture *t, Point sp)
 	}
 
 	c = cbuf2col(cbuf);
+	/* remove pre-multiplied alpha */
+	if(hasalpha(t->image->chan) && c.a > 0 && c.a < 1){
+		c.r /= c.a;
+		c.g /= c.a;
+		c.b /= c.a;
+	}
 	switch(t->type){
 	case sRGBTexture: c = srgb2linear(c); break;
 	}