X-Git-Url: http://de.git.xonotic.org/?p=xonotic%2Fdarkplaces.git;a=blobdiff_plain;f=fractalnoise.c;h=06d00db0eedbc805291b94771b13178d17bbcc42;hp=31b140d518972459b866a85687df6722d056efa3;hb=138ae5bad85c0c2b77a1c9a312bab39a5560ac48;hpb=d57be67cb00229acb8564b92c8b7c58eeed8a0cb

diff --git a/fractalnoise.c b/fractalnoise.c
index 31b140d5..06d00db0 100644
--- a/fractalnoise.c
+++ b/fractalnoise.c
@@ -1,7 +1,7 @@
 
 #include "quakedef.h"
 
-void fractalnoise(byte *noise, int size, int startgrid)
+void fractalnoise(qbyte *noise, int size, int startgrid)
 {
 	int x, y, g, g2, amplitude, min, max, size1 = size - 1, sizepower, gridpower;
 	int *noisebuf;
@@ -32,7 +32,7 @@ void fractalnoise(byte *noise, int size, int startgrid)
 		g = g2 >> 1;
 		if (g)
 		{
-			// subdivide, diamond-square algorythm (really this has little to do with squares)
+			// subdivide, diamond-square algorithm (really this has little to do with squares)
 			// diamond
 			for (y = 0;y < size;y += g2)
 				for (x = 0;x < size;x += g2)
@@ -59,7 +59,55 @@ void fractalnoise(byte *noise, int size, int startgrid)
 	// normalize noise and copy to output
 	for (y = 0;y < size;y++)
 		for (x = 0;x < size;x++)
-			*noise++ = (byte) (((n(x,y) - min) * 256) / max);
+			*noise++ = (qbyte) (((n(x,y) - min) * 256) / max);
 	Mem_Free(noisebuf);
 #undef n
 }
+
+// unnormalized, used for explosions mainly, does not allocate/free memory (hence the name quick)
+void fractalnoisequick(qbyte *noise, int size, int startgrid)
+{
+	int x, y, g, g2, amplitude, size1 = size - 1, sizepower, gridpower;
+#define n(x,y) noise[((y)&size1)*size+((x)&size1)]
+
+	for (sizepower = 0;(1 << sizepower) < size;sizepower++);
+	if (size != (1 << sizepower))
+		Sys_Error("fractalnoise: size must be power of 2\n");
+
+	for (gridpower = 0;(1 << gridpower) < startgrid;gridpower++);
+	if (startgrid != (1 << gridpower))
+		Sys_Error("fractalnoise: grid must be power of 2\n");
+
+	startgrid = bound(0, startgrid, size);
+
+	amplitude = 255; // this gets halved before use
+	memset(noise, 0, size*size);
+
+	for (g2 = startgrid;g2;g2 >>= 1)
+	{
+		// brownian motion (at every smaller level there is random behavior)
+		amplitude >>= 1;
+		for (y = 0;y < size;y += g2)
+			for (x = 0;x < size;x += g2)
+				n(x,y) += (rand()&amplitude);
+
+		g = g2 >> 1;
+		if (g)
+		{
+			// subdivide, diamond-square algorithm (really this has little to do with squares)
+			// diamond
+			for (y = 0;y < size;y += g2)
+				for (x = 0;x < size;x += g2)
+					n(x+g,y+g) = (qbyte) (((int) n(x,y) + (int) n(x+g2,y) + (int) n(x,y+g2) + (int) n(x+g2,y+g2)) >> 2);
+			// square
+			for (y = 0;y < size;y += g2)
+				for (x = 0;x < size;x += g2)
+				{
+					n(x+g,y) = (qbyte) (((int) n(x,y) + (int) n(x+g2,y) + (int) n(x+g,y-g) + (int) n(x+g,y+g)) >> 2);
+					n(x,y+g) = (qbyte) (((int) n(x,y) + (int) n(x,y+g2) + (int) n(x-g,y+g) + (int) n(x+g,y+g)) >> 2);
+				}
+		}
+	}
+#undef n
+}
+