add spotlight params and a light color shading routine. other things.

among these other things are clamping the color
channels to [0,1] internally, and adding a
modulation function for mixing colors/points.

1 files changed, 18 insertions, 0 deletions

diff --git a/shadeop.c b/shadeop.c
index c6080e3..4b74256 100644
--- a/shadeop.c
+++ b/shadeop.c
@@ -30,3 +30,21 @@ smoothstep(double edge0, double edge1, double n)
 	t = fclamp((n-edge0)/(edge1-edge0), 0, 1);
 	return t*t * (3 - 2*t);
 }
+
+/* TODO apply attenuation for punctual lights */
+Color
+getlightcolor(LightSource *l, Point3 dir)
+{
+	double cθs, cθu, cθp, t;
+
+	/* see “Spotlights”, Real-Time Rendering 4th ed. § 5.2.2 */
+	if(l->type == LIGHT_SPOT){
+		cθs = dotvec3(mulpt3(dir, -1), l->dir);
+		cθu = cos(l->θu);
+		cθp = cos(l->θp);
+//		return mulpt3(l->c, smoothstep(cθu, cθp, cθs));
+		t = fclamp((cθs - cθu)/(cθp - cθu), 0, 1);
+		return mulpt3(l->c, t*t);
+	}
+	return l->c;
+}