From 8bd56f42aa9abaae62985c8837afc42cc75f2a42 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+git@gmail.com>
Date: Sun, 1 May 2011 08:34:13 -0400
Subject: [PATCH] first lighting attempt; specular not working

---
 lighting/f_shader.glsl | 28 +++++++++++++++++++++++++++-
 lighting/test.cc       | 21 +++++++++++++--------
 lighting/v_shader.glsl |  9 ++++++++-
 3 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/lighting/f_shader.glsl b/lighting/f_shader.glsl
index db724ca..e1fdafb 100644
--- a/lighting/f_shader.glsl
+++ b/lighting/f_shader.glsl
@@ -1,5 +1,31 @@
 
+varying vec3 eye_pos_i;
+varying vec3 normal_i;
+varying vec4 diffuse_i;
+
 void main(void)
 {
-    gl_FragColor = gl_Color;
+    vec3 n, lightDir;
+    vec4 color;
+    float NdotL, RdotEye;
+
+    lightDir = vec3(-0.1, 0, -0.9);
+    color = vec4(0.2, 0.2, 0.2, 1.0);  /* ambient light */
+    n = normalize(normal_i);
+
+    NdotL = max(dot(n, -lightDir), 0.0);
+
+    if (NdotL > 0.0)
+    {
+        /* diffuse component */
+        color += diffuse_i * NdotL;
+        /* specular component */
+        RdotEye = dot(normalize(eye_pos_i), normalize(reflect(-lightDir, n)));
+        if (RdotEye > 0.0)
+        {
+            color += pow(RdotEye, 96.5);
+        }
+    }
+
+    gl_FragColor = color;
 }
diff --git a/lighting/test.cc b/lighting/test.cc
index 73db8bb..1c98886 100644
--- a/lighting/test.cc
+++ b/lighting/test.cc
@@ -15,13 +15,13 @@ using namespace std;
 #define STRIDE(a, b) ((unsigned long)(b) - (unsigned long)(a))
 #define OFFSET(a, b) ((const GLvoid *)STRIDE((a), (b)))
 
-const GLfloat data[][2][3] = {
-    {{-1.0, -0.6, 0.0}, {1, 0, 0}},
-    {{-0.2, -0.6, 0.0}, {0, 1, 0}},
-    {{-0.6, 0.6, 0.0}, {0, 0, 1}},
-    {{0.2, -0.6, 0.0}, {1, 0, 0}},
-    {{1.0, -0.6, 0.0}, {0, 1, 0}},
-    {{0.6, 0.6, -10.0}, {0, 0, 1}}
+const GLfloat data[][3][3] = {
+    {{-1.0, -0.6, 0.0}, {1, 0, 0}, {0, 0, 1}},
+    {{-0.2, -0.6, 0.0}, {0, 1, 0}, {0, 0, 1}},
+    {{-0.6, 0.6, 0.0}, {0, 0, 1}, {0, 0, 1}},
+    {{0.2, -0.6, 0.0}, {1, 0, 0}, {0, 0.7071, 0.7071}},
+    {{1.0, -0.6, 0.0}, {0, 1, 0}, {0, 0.7071, 0.7071}},
+    {{0.6, 0.6, -10.0}, {0, 0, 1}, {0, 0.7071, 0.7071}}
 };
 const GLushort indices[] = {
     0, 1, 2, 3, 4, 5
@@ -29,7 +29,8 @@ const GLushort indices[] = {
 GLuint program, vs, fs, data_vbo, index_vbo;
 enum Locations {
     LOC_POSITION,
-    LOC_COLOR
+    LOC_COLOR,
+    LOC_NORMAL
 };
 
 char * loadFile(const char *fname)
@@ -154,6 +155,7 @@ bool init(int width, int height)
 
     glBindAttribLocation(program, LOC_POSITION, "pos");
     glBindAttribLocation(program, LOC_COLOR, "color");
+    glBindAttribLocation(program, LOC_NORMAL, "normal");
 
     glLinkProgram(program);
 
@@ -183,10 +185,13 @@ void display(void)
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_vbo);
     glEnableVertexAttribArray(LOC_POSITION);
     glEnableVertexAttribArray(LOC_COLOR);
+    glEnableVertexAttribArray(LOC_NORMAL);
     glVertexAttribPointer(LOC_POSITION, 3, GL_FLOAT, GL_FALSE,
             STRIDE(&data[0], &data[1]), OFFSET(&data[0], &data[0][0]));
     glVertexAttribPointer(LOC_COLOR, 3, GL_FLOAT, GL_FALSE,
             STRIDE(&data[0], &data[1]), OFFSET(&data[0], &data[0][1]));
+    glVertexAttribPointer(LOC_NORMAL, 3, GL_FLOAT, GL_FALSE,
+            STRIDE(&data[0], &data[1]), OFFSET(&data[0], &data[0][2]));
     glDrawElements(GL_TRIANGLES, sizeof(indices)/sizeof(indices[0]),
             GL_UNSIGNED_SHORT, OFFSET(&indices, &indices[0]));
     SDL_GL_SwapBuffers();
diff --git a/lighting/v_shader.glsl b/lighting/v_shader.glsl
index c76673f..4881a17 100644
--- a/lighting/v_shader.glsl
+++ b/lighting/v_shader.glsl
@@ -1,9 +1,16 @@
 
 attribute vec3 pos;
 attribute vec3 color;
+attribute vec3 normal;
+
+varying vec3 eye_pos_i;
+varying vec3 normal_i;
+varying vec4 diffuse_i;
 
 void main(void)
 {
     gl_Position = gl_ModelViewProjectionMatrix * vec4(pos, 1);
-    gl_FrontColor = vec4(color, 1);
+    eye_pos_i = vec3(gl_Position.x, gl_Position.y, gl_Position.z);
+    normal_i = gl_NormalMatrix * normal;
+    diffuse_i = vec4(color, 1);
 }