From 59ab0befd5f3d6ea6a2b72aeeb045ab93103995a Mon Sep 17 00:00:00 2001
From: Ash Tyndall <git@atyndall.net>
Date: Tue, 18 Oct 2011 11:39:37 +0800
Subject: [PATCH]

---
 scene.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/scene.c b/scene.c
index 34824a4..6c9540a 100644
--- a/scene.c
+++ b/scene.c
@@ -527,6 +527,11 @@ drawFloor(void)
 }
 
 
+static GLfloat lightColor[] = {0.8, 1.0, 0.8, 1.0}; /* green-tinted */
+static GLfloat lightPosition[4];
+static float lightAngle = 0.0, lightHeight = 20;
+
+
 /**
  * Display function
  */
@@ -553,6 +558,47 @@ void display() {
 
    glMatrixMode(GL_PROJECTION);
   glLoadIdentity();*/
+
+
+   /* Reposition the light source. */
+  lightPosition[0] = 12*cos(lightAngle);
+  lightPosition[1] = lightHeight;
+  lightPosition[2] = 12*sin(lightAngle);
+  //if (directionalLight) {
+    lightPosition[3] = 0.0;
+  //} else {
+  //  lightPosition[3] = 1.0;
+  //}
+
+    glPushMatrix();
+
+    /* Tell GL new light source position. */
+    glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);
+
+       /* Draw "bottom" of floor in blue. */
+    glFrontFace(GL_CW);  /* Switch face orientation. */
+    glColor4f(0.1, 0.1, 0.7, 1.0);
+    drawFloor();
+    glFrontFace(GL_CCW);
+
+        /* Draw "top" of floor.  Use blending to blend in reflection. */
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+    glColor4f(0.7, 0.0, 0.0, 0.3);
+    glColor4f(1.0, 1.0, 1.0, 0.3);
+    drawFloor();
+    glDisable(GL_BLEND);
+
+        glPushMatrix();
+    glDisable(GL_LIGHTING);
+
+     /* Draw a yellow ball at the light source. */
+      glTranslatef(lightPosition[0], lightPosition[1], lightPosition[2]);
+      glutSolidSphere(1.0, 5, 5);
+
+          glEnable(GL_LIGHTING);
+    glPopMatrix();
+
    drawFloor();
    glutSwapBuffers();
 }
@@ -567,6 +613,7 @@ void init() {
   glMatrixMode(GL_MODELVIEW);
 }
 
+
 /**
  * Main function
  * @param argc Number of arguments
@@ -617,5 +664,12 @@ int main(int argc, char **argv) {
     0.0, 8.0, 0.0,      /* center is at (0,8,0) */
     0.0, 1.0, 0.);      /* up is in postivie Y direction */
 
+    glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, 1);
+  glLightfv(GL_LIGHT0, GL_DIFFUSE, lightColor);
+  glLightf(GL_LIGHT0, GL_CONSTANT_ATTENUATION, 0.1);
+  glLightf(GL_LIGHT0, GL_LINEAR_ATTENUATION, 0.05);
+  glEnable(GL_LIGHT0);
+  glEnable(GL_LIGHTING);
+
     glutMainLoop();
 }
-- 
2.20.1