Add generic routines to generate surfaces of revolution.

4 files changed, 208 insertions, 1 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 6230523..b84e560 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -24,7 +24,7 @@ AM_CXXFLAGS=-I../include
 AM_CFLAGS=-I../include
 
 lib_LIBRARIES = libGLU3.a
-libGLU3_a_SOURCES = matrix.c load_text.c arcball.c
+libGLU3_a_SOURCES = matrix.c load_text.c arcball.c revolve.c
 
 libGLU3includedir = ${includedir}
 libGLU3include_HEADERS = ../include/glu3.h ../include/glu3_scalar.h
diff --git a/src/revolve.c b/src/revolve.c
new file mode 100644
index 0000000..ff41029
--- /dev/null
+++ b/src/revolve.c
@@ -0,0 +1,116 @@
+/*
+ * Copyright © 2010 Ian D. Romanick
+ *
+ * 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.
+ */
+
+#include "revolve.h"
+
+void
+revolve(const GLUvec4 *points, const GLUvec4 *normals, const float *u,
+	unsigned num_points, 
+	const GLUvec4 *axis,
+	unsigned steps, float start_angle, float end_angle,
+	revolve_cb *cb, void *data)
+{
+	const float angle_step = (end_angle - start_angle) / (float) steps;
+	const GLUvec4 tangent = {{ 0.0, 0.0, 1.0, 0.0 }};
+	unsigned i;
+	unsigned j;
+
+
+	for (i = 0; i < steps; i++) {
+		const float a = start_angle + (angle_step * i);
+		const float v = i / (steps - 1);
+		GLUmat4 r;
+
+		/* Generate a rotation matrix to rotate the position and the
+		 * normal around the axis by the current angular step.  This
+		 * generates the new position and normal.
+		 */
+		gluRotate4v(& r, axis, a);
+
+		for (j = 0; j < num_points; j++) {
+			GLUvec4 p;
+			GLUvec4 n;
+			GLUvec4 t;
+			GLUvec4 uv;
+
+			gluMult4m_4v(& p, & r, & points[j]);
+			gluMult4m_4v(& n, & r, & normals[j]);
+			gluMult4m_4v(& t, & r, & tangent);
+
+			uv.values[0] = u[j];
+			uv.values[1] = v;
+			uv.values[2] = 0.0;
+			uv.values[3] = 0.0;
+
+			(*cb)(data, & p, & n, & t, & uv);
+		}
+	}
+}
+
+
+void
+generate_sphere(double radius, unsigned slices, unsigned stacks,
+		_Bool normals_point_out,
+		revolve_cb *cb, void *data)
+{
+	const GLUvec4 y_axis = {{ 0.0, 1.0, 0.0, 0.0 }};
+	GLUvec4 *positions;
+	GLUvec4 *normals;
+	float *u;
+	double latitude_step;
+	unsigned i;
+
+	positions = (GLUvec4 *) malloc((2 * sizeof(GLUvec4) + sizeof(float))
+				       * (stacks + 1));
+	normals = positions + (stacks + 1);
+	u = (float *)(normals + (stacks + 1));
+
+	latitude_step = M_PI / (double)(stacks);
+	for (i = 0; i < (stacks + 1); i++) {
+		const double latitude = latitude_step * i;
+
+		normals[i].values[0] = sin(latitude);
+		normals[i].values[1] = cos(latitude);
+		normals[i].values[2] = 0.0;
+		normals[i].values[3] = 0.0;
+
+		gluMult4v_f(& positions[i],
+			    & normals[i],
+			    radius);
+		positions[i].values[3] = 1.0;
+
+		u[i] = (float) i / (float) stacks;
+
+		if (!normals_point_out) {
+			normals[i].values[0] = -normals[i].values[0];
+			normals[i].values[1] = -normals[i].values[1];
+		}
+	}
+
+	/* Note the rotation is *from* 2pi *to* 0.  The counter-clockwise
+	 * rotation ensures that the vertices are generated in the correct
+	 * order to be drawn using triangle strips with back-face culling.
+	 */
+	revolve(positions, normals, u, stacks + 1, & y_axis,
+		slices + 1, 2.0 * M_PI, 0.0, cb, data);
+}
diff --git a/src/revolve.h b/src/revolve.h
new file mode 100644
index 0000000..960a50d
--- /dev/null
+++ b/src/revolve.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright © 2010 Ian D. Romanick
+ *
+ * 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.
+ */
+
+#include "system.h"
+#include "glu3.h"
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+typedef void (revolve_cb)(void *data, const GLUvec4 *position,
+			  const GLUvec4 *normal, const GLUvec4 *tangent,
+			  const GLUvec4 *uv);
+
+/**
+ * Generate a surface of revolution
+ *
+ * \param points      Points that define the outline of the shape to be
+ *                    revolved.
+ * \param normals     Initial per-vertex normals.
+ * \param u           Per-vertex position in parameter-space along the u-axis.
+ * \param num_points  Number of points in \c points, \c normals, and \c u.
+ * \param axis        Axis around which to rotate.
+ * \param steps       Total number of steps to rotate through.  The angle of
+ *                    rotation at the first step will be \c start_angle, and
+ *                    the angle of rotation at the last step will be
+ *                    \c end_angle.
+ * \param start_angle Initial angle of rotation.
+ * \param end_angle   Final angle of rotation.
+ * \param cb          Per-vertex call-back function.
+ * \param data        User-supplied data pointer passed to the per-vertex
+ *                    call-back function.
+ *
+ * \note
+ * Per-vertex tangents are generate based on the assumption that all of the
+ * initial vertices lie within the X-Y plane and that the axis of revolution
+ * also lies within the X-Y plane.
+ */
+extern void
+revolve(const GLUvec4 *points, const GLUvec4 *normals, const float *u,
+	unsigned num_points, 
+	const GLUvec4 *axis,
+	unsigned steps, float start_angle, float end_angle,
+	revolve_cb *cb, void *data);
+
+extern void
+generate_sphere(double radius, unsigned slices, unsigned stacks,
+		bool normals_point_out, revolve_cb *cb, void *data);
+
+#ifdef __cplusplus
+};
+#endif
diff --git a/src/system.h b/src/system.h
new file mode 100644
index 0000000..39d20d4
--- /dev/null
+++ b/src/system.h
@@ -0,0 +1,19 @@
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#ifdef HAVE_STDBOOL_H
+# include <stdbool.h>
+#else
+# ifndef HAVE__BOOL
+#  ifdef __cplusplus
+typedef bool _Bool;
+#  else
+#   define _Bool signed char
+#  endif
+# endif
+# define bool _Bool
+# define false 0
+# define true 1
+# define __bool_true_false_are_defined 1
+#endif