Phong model for lighting

git-svn-id: svn://cook.msm.cam.ac.uk:745/thrust3d/thrust3d@208 84d2e878-0bd5-11dd-ad15-13eda11d74c5

2 files changed, 26 insertions, 24 deletions

diff --git a/data/shaders/lighting.frag b/data/shaders/lighting.frag
index 1bc0afd..5545b03 100644
--- a/data/shaders/lighting.frag
+++ b/data/shaders/lighting.frag
@@ -9,13 +9,14 @@
  *
  */
 
+varying vec3 pos;
 varying vec3 normal;
 
 varying vec3 light0vc;
-varying vec3 light0hvc;
+varying float light0dist;
+
 varying vec3 light1vc;
 varying vec3 light2vc;
-varying vec3 light2hvc;
 
 uniform sampler2D texture;
 uniform sampler2D normalmap;
@@ -52,31 +53,32 @@ void main() {
 	/* Fill-in light (light 2) */
 	if ( fill_light_enabled ) {
 		
-		float ndothv;
+		float diff_fac, spec_fac;
+		
+		diff_fac = max(dot(norm, normalize(light2vc)), 0.0);
+		diff += col_ambi_diff * gl_LightSource[2].diffuse.rgb * diff_fac;
 		
-		ndothv = max(dot(norm, normalize(light2hvc)), 0.0);
-		diff += col_ambi_diff * gl_LightSource[2].diffuse.rgb * max(dot(vec3(light1vc), norm), 0.0);
-		spec += gl_LightSource[2].specular.rgb * pow(ndothv, 80.0);
-
 	} else {
 	
 		/* Spotlight (light 0) - positional, spotlight */
-		float falloff;
-		float spot;
-		float ndothv;
+		float falloff, spot;
+		float diff_fac, spec_fac;
 		
 		falloff = 1/ (  gl_LightSource[0].constantAttenuation
-			            + gl_LightSource[0].linearAttenuation * length(light0vc)
-			            + gl_LightSource[0].quadraticAttenuation * pow(length(light0vc), 2.0) );
+			            + gl_LightSource[0].linearAttenuation * light0dist
+			            + gl_LightSource[0].quadraticAttenuation * pow(light0dist, 2.0) );
+		
 		spot = max(dot(normalize(-light0vc), gl_LightSource[0].spotDirection), 0.0);
 		spot = pow(spot, gl_LightSource[0].spotExponent);
 		
-		ndothv = max(dot(norm, normalize(light0hvc)), 0.0);
+		diff_fac = max(dot(norm, normalize(light0vc)), 0.0);
+		diff += col_ambi_diff * gl_LightSource[0].diffuse.rgb * spot * falloff * diff_fac;
 		
-		diff += col_ambi_diff * gl_LightSource[0].diffuse.rgb * spot * falloff *
-									max(dot(normalize(light0vc).xyz, norm), 0.0);
+		vec3 E = normalize(-pos);
+		vec3 R = normalize(-reflect(light0vc, norm)); 
 		
-		spec += vec3(1.0, 1.0, 1.0) * gl_LightSource[0].specular.rgb * spot * falloff * pow(ndothv, 80.0);
+		spec_fac = pow(max(0.0, dot(R, E)), 80.0);
+		spec += vec3(1.0, 1.0, 1.0) * gl_LightSource[0].specular.rgb * spot * falloff * spec_fac;
 		
 		/* Background glow (light 1) - diffuse only, directional */
 		diff += col_ambi_diff * gl_LightSource[1].diffuse.rgb * max(dot(vec3(light1vc), norm), 0.0);
diff --git a/data/shaders/lighting.vert b/data/shaders/lighting.vert
index 7f9d606..59d026d 100644
--- a/data/shaders/lighting.vert
+++ b/data/shaders/lighting.vert
@@ -9,13 +9,14 @@
  *
  */
 
+varying vec3 pos;
 varying vec3 normal;
 
 varying vec3 light0vc;
-varying vec3 light0hvc;
+varying float light0dist;
+
 varying vec3 light1vc;
 varying vec3 light2vc;
-varying vec3 light2hvc;
 
 varying vec3 col_ambi_diff;
 varying vec3 col_emit;
@@ -23,16 +24,16 @@ varying vec3 col_emit;
 void main() {
 	
 	vec4 vert;
-	vec4 E;
+	vec3 vert_to_light;
 	
 	vert = gl_ModelViewMatrix * gl_Vertex;
+	pos = vec3(vert);
 	normal = gl_NormalMatrix * gl_Normal;
-	E = vec4(0.0, 0.0, 1.0, 0.0) - vert;
 	
 	/* Spotlight - positional light */
-	light0vc = vec3(gl_LightSource[0].position - vert);
-	light0hvc = normalize(vec3(E) + light0hvc);
-	light0vc = normalize(light0vc);
+	vert_to_light = vec3(gl_LightSource[0].position - vert);
+	light0dist = length(vert_to_light);
+	light0vc = normalize(vert_to_light);
 	
 	/* Diffuse "background glow" - this can be normalised only once, here, since 'position'
 	 * is really 'direction' and is the same for all vertices. */
@@ -40,7 +41,6 @@ void main() {
 	
 	/* Fill-in light */
 	light2vc = normalize(vec3(gl_LightSource[2].position));
-	light2hvc = normalize(vec3(E) + light2vc);
 	
 	/* Material properties */
 	col_ambi_diff = gl_Color.rgb;