Cycles: Add support for single channel byte textures.

This way, we also save 3/4th of memory for single channel byte textures (e.g. Bump Maps).

Note: In order for this to work, the texture *must* have 1 channel only.
In Gimp you can e.g. do that via the menu: Image -> Mode -> Grayscale

intern/cycles/kernel/kernels/cpu/kernel.cpp

@@ -138,6 +138,22 @@ void kernel_tex_copy(KernelGlobals *kg,
 			tex->extension = extension;
 		}
 	}
+	else if(strstr(name, "__tex_image_byte")) {
+		texture_image_uchar *tex = NULL;
+		int id = atoi(name + strlen("__tex_image_byte_"));
+		int array_index = id - TEX_IMAGE_BYTE_START_CPU;
+
+		if(array_index >= 0 && array_index < TEX_NUM_BYTE_IMAGES_CPU) {
+			tex = &kg->texture_byte_images[array_index];
+		}
+
+		if(tex) {
+			tex->data = (uchar*)mem;
+			tex->dimensions_set(width, height, depth);
+			tex->interpolation = interpolation;
+			tex->extension = extension;
+		}
+	}
 	else
 		assert(0);
 }