GLUshape: Split GLUshape into GLUshapeConsumer and GLUshape

Put the responsibility for storing the data in a separate consumer
class.  As a result, applications that want to store data from
n GLUshape subclasses in the same manner need only create one subclass
(of GLUshapeConsumer) instead of n (of GLUshape).

3 files changed, 92 insertions, 82 deletions

diff --git a/include/glu3.h b/include/glu3.h
index 95be831..6e809e5 100644
--- a/include/glu3.h
+++ b/include/glu3.h
@@ -270,23 +270,62 @@ struct GLUarcball {
 
 #ifdef __cplusplus
 /**
- * Base class of a shape generators.
+ * Consumer for shape data generated by a GLUshape object
  *
- * Base class defines the interface for all shape generators.  Concrete shape
- * generator class are expected to implement:
+ * Objects of this class and its descenents are used to consume data generated
+ * by \c GLUshape.  The \c GLUshape object is responsible for the format of
+ * the data generate, and the \c GLUshapeConsumer object is repsonsible for
+ * storing that data.
  *
- *  * \c vertex_count
- *  * \c element_count
- *  * \c primitive_count
- *  * \c generate
+ * This splits the functionality of the classic GLU's \c GLUquadric structure.
  *
- * Consumers of generated data are expected to subclass concrete shape
- * generators.  These classes are expected to implement:
+ * \sa GLUshape
+ */
+class GLUshapeConsumer {
+public:
+	/**
+	 * Emit an individual vertex
+	 *
+	 * \param position  Object-space position of the vertex.
+	 * \param normal    Object-space normal of the vertex.
+	 * \param tangent   Object-space tangent of the vertex.
+	 * \param uv        Parameter-space position of the vertex.  The
+	 *                  per-vertex values will range from (0,0,0,0) to
+	 *                  (1, 1, 0, 0).
+	 */
+	virtual void vertex(const GLUvec4 &position,
+			    const GLUvec4 &normal,
+			    const GLUvec4 &tangent,
+			    const GLUvec4 &uv) = 0;
+
+	/**
+	 * Start a new indexed primitive.
+	 *
+	 * \param mode  GL primitive drawing mode used for this primitive
+	 */
+	virtual void begin_primitive(GLenum mode) = 0;
+
+	/**
+	 * Emit an element index for drawing
+	 */
+	virtual void index(unsigned idx) = 0;
+
+	/**
+	 * End an index primitive previously started with begin_primitive
+	 */
+	virtual void end_primitive(void) = 0;
+};
+
+
+/**
+ * Base class of a shape generators.
  *
- *  * \c emit_vertex
- *  * \c emit_begin
- *  * \c emit_index
- *  * \c emit_end
+ * Base class defines the interface for all shape generators.  Each concrete
+ * subclass is responsible for providing the pure virtual query and data
+ * generation methods.  Data produced by a shape generator is pushed to a
+ * \c GLUshapeConsumer as it is generated.
+ *
+ * \sa GLUshapeConsumer
  */
 class GLUshape {
 public:
@@ -337,49 +376,17 @@ public:
 	 * Generate the primitive
 	 *
 	 * Causes the data for the primitive to be generated.  This will result
-	 * in the \c emit_vertex, \c emit_begin, \c emit_index, and \c emit_end
-	 * methods to be invoked with the data as it is generated.
+	 * in the \c vertex, \c begin_primitive, \c index, and \c end_primitive
+	 * methods of \c consumer being invoked with the data as it is
+	 * generated.
 	 */
-	virtual void generate(void) = 0;
+	virtual void generate(GLUshapeConsumer *consumer) const = 0;
 
 protected:
 	GLUshape(void) : normals_point_out(true), normals_per_vertex(true)
 	{
 	}
 
-
-	/**
-	 * Callback function used to emit individual vertices.
-	 *
-	 * \param position  Object-space position of the vertex.
-	 * \param normal    Object-space normal of the vertex.
-	 * \param tangent   Object-space tangent of the vertex.
-	 * \param uv        Parameter-space position of the vertex.  The
-	 *                  per-vertex values will range from (0,0,0,0) to
-	 *                  (1, 1, 0, 0).
-	 */
-	virtual void emit_vertex(const GLUvec4 &position,
-				 const GLUvec4 &normal,
-				 const GLUvec4 &tangent,
-				 const GLUvec4 &uv) = 0;
-
-	/**
-	 * Start a new indexed primitive.
-	 *
-	 * \param mode  GL primitive drawing mode used for this primitive
-	 */
-	virtual void emit_begin(GLenum mode) = 0;
-
-	/**
-	 * Callback function used to emit element indices used for drawing
-	 */
-	virtual void emit_index(unsigned idx) = 0;
-
-	/**
-	 * End an index primitive previously started with emit_begin.
-	 */
-	virtual void emit_end(void) = 0;
-
 	bool normals_point_out;
 	bool normals_per_vertex;
 };
@@ -405,7 +412,7 @@ public:
 	virtual unsigned vertex_count(void) const;
 	virtual unsigned element_count(void) const;
 	virtual unsigned primitive_count(void) const;
-	virtual void generate(void);
+	virtual void generate(GLUshapeConsumer *consumer) const;
 
 private:
 	double radius;
diff --git a/src/sphere.cpp b/src/sphere.cpp
index f51160e..ecd7db8 100644
--- a/src/sphere.cpp
+++ b/src/sphere.cpp
@@ -1,5 +1,4 @@
 /*
-
  * Copyright © 2010 Ian D. Romanick
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
@@ -61,7 +60,7 @@ static void sphere_end_cb(void *data);
  * This is arguably a mis-use of the "decorator" pattern, but it is the most
  * efficient way to do this.
  */
-class GLUsphereFriend : public GLUsphere {
+class GLUconsumerFriend : public GLUshapeConsumer {
 	friend void sphere_revolve_cb(void *data,
 				      const GLUvec4 *position,
 				      const GLUvec4 *normal,
@@ -119,49 +118,49 @@ static void
 sphere_revolve_cb(void *data, const GLUvec4 *position, const GLUvec4 *normal,
 		  const GLUvec4 *tangent, const GLUvec4 *uv)
 {
-	GLUsphereFriend *s = (GLUsphereFriend *) data;
+	GLUconsumerFriend *c = (GLUconsumerFriend *) data;
 
-	s->emit_vertex(*position, *normal, *tangent, *uv);
+	c->vertex(*position, *normal, *tangent, *uv);
 }
 
 
 static void
 sphere_begin_cb(void *data, GLenum mode)
 {
-	GLUsphereFriend *s = (GLUsphereFriend *) data;
+	GLUconsumerFriend *c = (GLUconsumerFriend *) data;
 
-	s->emit_begin(mode);
+	c->begin_primitive(mode);
 }
 
 
 static void
 sphere_index_cb(void *data, unsigned index)
 {
-	GLUsphereFriend *s = (GLUsphereFriend *) data;
+	GLUconsumerFriend *c = (GLUconsumerFriend *) data;
 
-	s->emit_index(index);
+	c->index(index);
 }
 
 
 static void
 sphere_end_cb(void *data)
 {
-	GLUsphereFriend *s = (GLUsphereFriend *) data;
+	GLUconsumerFriend *c = (GLUconsumerFriend *) data;
 
-	s->emit_end();
+	c->end_primitive();
 }
 
 
 void
-GLUsphere::generate(void)
+GLUsphere::generate(GLUshapeConsumer *consumer) const
 {
 	generate_sphere(radius, slices, stacks,
 			normals_point_out,
-			sphere_revolve_cb, (void *) this);
+			sphere_revolve_cb, (void *) consumer);
 
 	generate_triangle_mesh(slices, stacks + 1, stacks + 1,
 			       sphere_begin_cb,
 			       sphere_index_cb,
 			       sphere_end_cb,
-			       (void *) this);
+			       (void *) consumer);
 }
diff --git a/test/sphere.cpp b/test/sphere.cpp
index 9f5d94a..adcce4e 100644
--- a/test/sphere.cpp
+++ b/test/sphere.cpp
@@ -2,12 +2,13 @@
 #include <cstdio>
 #include "glu3.h"
 
-class check_sphere : public GLUsphere {
+class check_sphere : public GLUshapeConsumer {
 public:
-	check_sphere(double r, int sl, int st) :
-		GLUsphere(r, sl, st), pass(true), vert(0),
-		prim(0), elts(0), r(r), mode(0)
+	check_sphere(const GLUshape &shape, double r) :
+		pass(true), vert(0), prim(0), elts(0), r(r), mode(0)
 	{
+		primitive_count = shape.primitive_count();
+		vertex_count = shape.vertex_count();
 	}
 
 	bool pass;
@@ -17,8 +18,10 @@ public:
 	double r;
 	GLenum mode;
 
-protected:
-	virtual void emit_vertex(const GLUvec4 &position,
+	unsigned vertex_count;
+	unsigned primitive_count;
+
+	virtual void vertex(const GLUvec4 &position,
 				 const GLUvec4 &normal,
 				 const GLUvec4 &tangent,
 				 const GLUvec4 &tex_coord)
@@ -96,7 +99,7 @@ protected:
 		vert++;
 	}
 
-	virtual void emit_begin(GLenum mode)
+	virtual void begin_primitive(GLenum mode)
 	{
 		printf("prim %u: begin\n", prim);
 
@@ -107,7 +110,7 @@ protected:
 			pass = false;
 		}
 
-		if (prim == primitive_count()) {
+		if (prim == primitive_count) {
 			printf("prim %u: too many primitives\n",
 			       prim);
 			pass = false;
@@ -129,20 +132,20 @@ protected:
 		this->mode = mode;
 	}
 
-	virtual void emit_index(unsigned idx)
+	virtual void index(unsigned idx)
 	{
 		printf("prim %u, elt %u: %u\n", prim, elts, idx);
 
-		if (idx >= vertex_count()) {
+		if (idx >= vertex_count) {
 			printf("prim %u, elt %u: bad elt %u > %u\n",
-			       prim, elts, idx, vertex_count() - 1);
+			       prim, elts, idx, vertex_count - 1);
 			pass = false;
 		}
 
 		elts++;
 	}
 
-	virtual void emit_end(void)
+	virtual void end_primitive(void)
 	{
 		printf("prim %u: end\n", prim);
 
@@ -161,12 +164,13 @@ protected:
 int
 main(int argc, char **argv)
 {
-	check_sphere s(4.0, 5, 5);
-
-	s.generate();
-	assert(s.pass);
-	assert(s.vert == s.vertex_count());
-	assert(s.prim == s.primitive_count());
-	assert(s.elts == s.element_count());
+	GLUsphere s(4.0, 5, 5);
+	check_sphere c(s, 4.0);
+
+	s.generate(& c);
+	assert(c.pass);
+	assert(c.vert == s.vertex_count());
+	assert(c.prim == s.primitive_count());
+	assert(c.elts == s.element_count());
 	return 0;
 }