From fecc8a0e4423c54a08abc0a3183cda55c181f3d4 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+git@gmail.com>
Date: Fri, 6 May 2011 09:19:24 -0400
Subject: [PATCH] corrected phong lighting shader

---
 lighting/f_shader.glsl | 16 +++++++++-------
 lighting/test.cc       | 12 ++++++++++++
 lighting/v_shader.glsl |  7 ++-----
 3 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/lighting/f_shader.glsl b/lighting/f_shader.glsl
index e1fdafb..abca9aa 100644
--- a/lighting/f_shader.glsl
+++ b/lighting/f_shader.glsl
@@ -1,7 +1,9 @@
 
-varying vec3 eye_pos_i;
+uniform vec4 ambient, diffuse, specular;
+uniform float shininess;
+
+varying vec3 pos_i;
 varying vec3 normal_i;
-varying vec4 diffuse_i;
 
 void main(void)
 {
@@ -9,8 +11,8 @@ void main(void)
     vec4 color;
     float NdotL, RdotEye;
 
-    lightDir = vec3(-0.1, 0, -0.9);
-    color = vec4(0.2, 0.2, 0.2, 1.0);  /* ambient light */
+    lightDir = normalize(vec3(-0.4, 0, -0.9));
+    color = vec4(0.2, 0.2, 0.2, 1.0) * ambient;  /* ambient light */
     n = normalize(normal_i);
 
     NdotL = max(dot(n, -lightDir), 0.0);
@@ -18,12 +20,12 @@ void main(void)
     if (NdotL > 0.0)
     {
         /* diffuse component */
-        color += diffuse_i * NdotL;
+        color += diffuse * NdotL;
         /* specular component */
-        RdotEye = dot(normalize(eye_pos_i), normalize(reflect(-lightDir, n)));
+        RdotEye = dot(normalize(-pos_i), normalize(reflect(-lightDir, n)));
         if (RdotEye > 0.0)
         {
-            color += pow(RdotEye, 96.5);
+            color += clamp(specular * pow(RdotEye, shininess), 0.0, 1.0);
         }
     }
 
diff --git a/lighting/test.cc b/lighting/test.cc
index 1c98886..ae0aee0 100644
--- a/lighting/test.cc
+++ b/lighting/test.cc
@@ -27,6 +27,7 @@ const GLushort indices[] = {
     0, 1, 2, 3, 4, 5
 };
 GLuint program, vs, fs, data_vbo, index_vbo;
+GLint ambient_loc, diffuse_loc, specular_loc, shininess_loc;
 enum Locations {
     LOC_POSITION,
     LOC_COLOR,
@@ -171,6 +172,17 @@ bool init(int width, int height)
         return false;
     }
 
+    ambient_loc = glGetUniformLocation(program, "ambient");
+    diffuse_loc = glGetUniformLocation(program, "diffuse");
+    specular_loc = glGetUniformLocation(program, "specular");
+    shininess_loc = glGetUniformLocation(program, "shininess");
+
+    glUseProgram(program);
+    glUniform4f(ambient_loc, 0.2, 0.2, 0.2, 1.0);
+    glUniform4f(diffuse_loc, 1.0, 0.6, 0.0, 1.0);
+    glUniform4f(specular_loc, 1.0, 1.0, 1.0, 1.0);
+    glUniform1f(shininess_loc, 85.0);
+
     data_vbo = makeBuffer(GL_ARRAY_BUFFER, data, sizeof(data));
     index_vbo = makeBuffer(GL_ELEMENT_ARRAY_BUFFER, indices, sizeof(indices));
 
diff --git a/lighting/v_shader.glsl b/lighting/v_shader.glsl
index 4881a17..6fde1ce 100644
--- a/lighting/v_shader.glsl
+++ b/lighting/v_shader.glsl
@@ -1,16 +1,13 @@
 
 attribute vec3 pos;
-attribute vec3 color;
 attribute vec3 normal;
 
-varying vec3 eye_pos_i;
+varying vec3 pos_i;
 varying vec3 normal_i;
-varying vec4 diffuse_i;
 
 void main(void)
 {
     gl_Position = gl_ModelViewProjectionMatrix * vec4(pos, 1);
-    eye_pos_i = vec3(gl_Position.x, gl_Position.y, gl_Position.z);
+    pos_i = vec3(gl_Position.x, gl_Position.y, gl_Position.z);
     normal_i = gl_NormalMatrix * normal;
-    diffuse_i = vec4(color, 1);
 }