shithub: libgraphics

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fb: do a better greyscale to color raster conversion.

--- a/fb.c

+++ b/fb.c

@@ -81,16 +81,35 @@

 rasterconvF2C(Raster *dst, Raster *src)

 {

 	ulong *c, len;

-	float *f;

+	float *f, min, max;

 	uchar b;

-	c = dst->data;

+	/* first run: get the domain */

 	f = (float*)src->data;

 	len = Dx(dst->r)*Dy(dst->r);

+	for(min = 0, max = 0; len--; f++){

+		if(isInf(*f, -1))	/* -∞ is the DNotacolor of the z-buffer */

+			continue;

+		min = min(*f, min);

+		max = max(*f, max);

+	}

+	/* center it at zero: [min, max] → [0, max-min]*/

+	max -= min;

+	if(max == 0)

+		max = 1;

+	/* second run: average the values */

+	c = dst->data;

+	f = (float*)src->data;

+	len = Dx(dst->r)*Dy(dst->r);

 	while(len--){

-		b = fclamp(*f++, 0, 1)*0xFF;

-		*c++ = 0xFF<<24 | b<<16 | b<<8 | b;

+		if(isInf(*f, -1)){	/* -∞ is the DNotacolor of the z-buffer */

+			*c++ = 0x00;

+			f++;

+			continue;

+		}

+		b = (*f++ - min)/max * 0xFF;

+		*c++ = (b * 0x00010101)<<8 | 0xFF;

 	}

 }