From c99a1eacd073b39c7300a2627dad9f67f89554a4 Mon Sep 17 00:00:00 2001
From: Eric Anholt <eric@anholt.net>
Date: Fri, 31 Jul 2009 10:15:32 -0700
Subject: Add test for gluLookAt4v and fix a bug it revealed.

---
 .gitignore       |  1 +
 src/matrix.c     | 17 +++++++----
 test/Makefile.am |  5 +--
 test/lookat4v.c  | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 108 insertions(+), 8 deletions(-)
 create mode 100644 test/lookat4v.c

diff --git a/.gitignore b/.gitignore
index 430b2cf..339c871 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,3 +18,4 @@ autom4te.cache
 src/.deps
 test/.deps
 test/add4v_4v
+test/lookat4v
diff --git a/src/matrix.c b/src/matrix.c
index 48a862f..db3bd8d 100644
--- a/src/matrix.c
+++ b/src/matrix.c
@@ -54,13 +54,13 @@ void gluScale4v(GLUmat4 *result, const GLUvec4 *t)
 
 
 void gluLookAt4v(GLUmat4 *result,
-		 const GLUvec4 *eye,
-		 const GLUvec4 *center,
-		 const GLUvec4 *up)
+		 const GLUvec4 *_eye,
+		 const GLUvec4 *_center,
+		 const GLUvec4 *_up)
 {
 	static const GLUvec4 col3 = { { 0.0f, 0.0f, 0.0f, 1.0f } };
 	const GLUvec4 e = { 
-		{ -eye->values[0], -eye->values[1], -eye->values[2], 0.0f }
+		{ -_eye->values[0], -_eye->values[1], -_eye->values[2], 0.0f }
 	};
 	GLUmat4  translate;
 	GLUmat4  rotate;
@@ -68,12 +68,17 @@ void gluLookAt4v(GLUmat4 *result,
 	GLUvec4  f;
 	GLUvec4  s;
 	GLUvec4  u;
+	GLUvec4  center, up;
 
+	center = *_center;
+	center.values[3] = 0;
+	up = *_up;
+	up.values[3] = 0;
 
-	gluSub4v_4v(& f, center, eye);
+	gluAdd4v_4v(& f, &center, &e);
 	gluNormalize4v(& f, & f);
 
-	gluNormalize4v(& u, up);
+	gluNormalize4v(& u, &up);
 
 	gluCross4v(& s, & f, & u);
 	gluCross4v(& u, & s, & f);
diff --git a/test/Makefile.am b/test/Makefile.am
index b8a5c70..a0e33d2 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,8 +1,9 @@
 AM_CFLAGS = -I$(srcdir)/../include
-LDADD = ../src/libGLU3.a
+LDADD = ../src/libGLU3.a -lm
 
 TESTS = \
-	add4v_4v
+	add4v_4v \
+	lookat4v
 
 EXTRA_PROGRAMS = $(TESTS)
 CLEANFILES = $(EXTRA_PROGRAMS)
diff --git a/test/lookat4v.c b/test/lookat4v.c
new file mode 100644
index 0000000..892e0ef
--- /dev/null
+++ b/test/lookat4v.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright © 2009 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Eric Anholt <eric@anholt.net>
+ *
+ */
+
+#include <glu3.h>
+#include <assert.h>
+
+static GLboolean vec4_equals(const GLUvec4 *a, const GLUvec4 *b)
+{
+	int i;
+	for (i = 0; i < 4; i++) {
+		if (a->values[i] != b->values[i])
+			return GL_FALSE;
+	}
+
+	return GL_TRUE;
+}
+
+static void vec4_divide(GLUvec4 *a)
+{
+	a->values[0] /= a->values[3];
+	a->values[1] /= a->values[3];
+	a->values[2] /= a->values[3];
+	a->values[3] = 1.0;
+}
+
+int main(int argc, char **argv)
+{
+	GLUvec4 eye = {{0.0, 0.0, 0.0, 0.0}};
+	GLUvec4 center = {{0.0, 0.0, -1.0, 0.0}};
+	GLUvec4 up = {{0.0, 1.0, 0.0, 0.0}};
+	GLUvec4 result;
+	GLUmat4 identity_lookat;
+	GLUvec4 a = {{1.0, 2.0, 3.0, 1.0}};
+	GLUvec4 b = {{-2.0, 3.0, 5.0, 1.0}};
+
+	(void)argc;
+	(void)argv;
+
+	gluLookAt4v(&identity_lookat,
+		    &eye,
+		    &center,
+		    &up);
+	gluMult4m_4v(&result, &identity_lookat, &a);
+	vec4_divide(&result);
+	assert(vec4_equals(&result, &a));
+	gluMult4m_4v(&result, &identity_lookat, &b);
+	vec4_divide(&result);
+	assert(vec4_equals(&result, &b));
+
+	/* Make sure that LookAt doesn't take the 4th component
+	 * eye/center/up into account.
+	 */
+	eye.values[3] = 1.0;
+	center.values[3] = 1.0;
+	up.values[3] = 1.0;
+
+	gluLookAt4v(&identity_lookat,
+		    &eye,
+		    &center,
+		    &up);
+	gluMult4m_4v(&result, &identity_lookat, &a);
+	vec4_divide(&result);
+	assert(vec4_equals(&result, &a));
+	gluMult4m_4v(&result, &identity_lookat, &b);
+	vec4_divide(&result);
+	assert(vec4_equals(&result, &b));
+
+	return 0;
+}
-- 
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