add lookat for spotLight

close #834

src/operators/light/spotLight.glsl

@@ -9,6 +9,10 @@ ReturnT thismap(CoordT p, ContextT ctx) {
 	#endif
 	{
 		vec3 spotDir = normalize(THIS_Direction);
+		if (IS_TRUE(THIS_Enablelookat)) {
+			mat4 m = lookAtViewMatrix(light.pos, THIS_Lookatpos, THIS_Upvec);
+			spotDir = (m * vec4(spotDir, 0.0)).xyz;
+		}
 		pRotateOnXYZ(spotDir, THIS_Rotate);
 		float innerCutoffCos = cos(radians(THIS_Coneangle));
 		float outerCutoffCos = cos(radians(THIS_Coneangle + THIS_Conedelta));

src/operators/light/spotLight.yaml

@@ -1,7 +1,7 @@
 !rop
 meta: !meta
   opType: raytk.operators.light.spotLight
-  opVersion: '12'
+  opVersion: '13'
   opStatus: default
 opDef: !def
   enable: true

src/operators/light/spotLight_params.txt

@@ -1,4 +1,4 @@
 names	source	handling	readOnlyHandling	conversion	enable
-Position[xyz] Direction[xyz] Color[rgb] Intensity Coneangle Conedelta Attenuationstart Attenuationend	param	runtime	macro		1
-Enableattenuation Enableshadow	param	runtime	constant		1
+Position[xyz] Direction[xyz] Color[rgb] Intensity Coneangle Conedelta Attenuationstart Attenuationend Lookatpos[xyz] Upvec[xyz]	param	runtime	macro		1
+Enableattenuation Enableshadow Enablelookat	param	runtime	constant		1
 Rotate[xyz]	param	runtime	macro	angle	1