From 25a5dc2ea718863af84511491b9184d06a8c2931 Mon Sep 17 00:00:00 2001
From: Brian Paul <brian.paul@tungstengraphics.com>
Date: Tue, 27 Mar 2001 17:08:20 +0000
Subject: moved shadow code into teapot.c

---
 progs/demos/teapot.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 78 insertions(+), 1 deletion(-)

(limited to 'progs/demos/teapot.c')

diff --git a/progs/demos/teapot.c b/progs/demos/teapot.c
index cb1ba4b827..dd2eadf352 100644
--- a/progs/demos/teapot.c
+++ b/progs/demos/teapot.c
@@ -17,7 +17,6 @@
 
 #include <GL/glut.h>
 #include "readtex.c"
-#include "shadow.c"
 
 #ifdef XMESA
 #include "GL/xmesa.h"
@@ -66,6 +65,84 @@ static int joyactive=0;
 static GLuint t1id,t2id;
 static GLuint teapotdlist,basedlist,lightdlist;
 
+
+
+/******************** begin shadow code ********************/
+
+/* Taken from the projshadow.c - by Tom McReynolds, SGI */
+
+/* Modified by David Bucciarelli */
+
+enum {
+  X, Y, Z, W
+};
+enum {
+  A, B, C, D
+};
+
+/* create a matrix that will project the desired shadow */
+void
+shadowmatrix(GLfloat shadowMat[4][4],
+  GLfloat groundplane[4],
+  GLfloat lightpos[4])
+{
+  GLfloat dot;
+
+  /* find dot product between light position vector and ground plane normal */
+  dot = groundplane[X] * lightpos[X] +
+    groundplane[Y] * lightpos[Y] +
+    groundplane[Z] * lightpos[Z] +
+    groundplane[W] * lightpos[W];
+
+  shadowMat[0][0] = dot - lightpos[X] * groundplane[X];
+  shadowMat[1][0] = 0.f - lightpos[X] * groundplane[Y];
+  shadowMat[2][0] = 0.f - lightpos[X] * groundplane[Z];
+  shadowMat[3][0] = 0.f - lightpos[X] * groundplane[W];
+
+  shadowMat[X][1] = 0.f - lightpos[Y] * groundplane[X];
+  shadowMat[1][1] = dot - lightpos[Y] * groundplane[Y];
+  shadowMat[2][1] = 0.f - lightpos[Y] * groundplane[Z];
+  shadowMat[3][1] = 0.f - lightpos[Y] * groundplane[W];
+
+  shadowMat[X][2] = 0.f - lightpos[Z] * groundplane[X];
+  shadowMat[1][2] = 0.f - lightpos[Z] * groundplane[Y];
+  shadowMat[2][2] = dot - lightpos[Z] * groundplane[Z];
+  shadowMat[3][2] = 0.f - lightpos[Z] * groundplane[W];
+
+  shadowMat[X][3] = 0.f - lightpos[W] * groundplane[X];
+  shadowMat[1][3] = 0.f - lightpos[W] * groundplane[Y];
+  shadowMat[2][3] = 0.f - lightpos[W] * groundplane[Z];
+  shadowMat[3][3] = dot - lightpos[W] * groundplane[W];
+
+}
+
+/* find the plane equation given 3 points */
+void
+findplane(GLfloat plane[4],
+  GLfloat v0[3], GLfloat v1[3], GLfloat v2[3])
+{
+  GLfloat vec0[3], vec1[3];
+
+  /* need 2 vectors to find cross product */
+  vec0[X] = v1[X] - v0[X];
+  vec0[Y] = v1[Y] - v0[Y];
+  vec0[Z] = v1[Z] - v0[Z];
+
+  vec1[X] = v2[X] - v0[X];
+  vec1[Y] = v2[Y] - v0[Y];
+  vec1[Z] = v2[Z] - v0[Z];
+
+  /* find cross product to get A, B, and C of plane equation */
+  plane[A] = vec0[Y] * vec1[Z] - vec0[Z] * vec1[Y];
+  plane[B] = -(vec0[X] * vec1[Z] - vec0[Z] * vec1[X]);
+  plane[C] = vec0[X] * vec1[Y] - vec0[Y] * vec1[X];
+
+  plane[D] = -(plane[A] * v0[X] + plane[B] * v0[Y] + plane[C] * v0[Z]);
+}
+
+/******************** end shadow code ********************/
+
+
 static void calcposobs(void)
 {
   dir[0]=sin(alpha*M_PI/180.0);
-- 
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