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+//
+// Book: OpenGL(R) ES 2.0 Programming Guide
+// Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner
+// ISBN-10: 0321502795
+// ISBN-13: 9780321502797
+// Publisher: Addison-Wesley Professional
+// URLs: http://safari.informit.com/9780321563835
+// http://www.opengles-book.com
+//
+
+// ESShapes.c
+//
+// Utility functions for generating shapes
+//
+
+///
+// Includes
+//
+#include "esUtil.h"
+#include <stdlib.h>
+#include <math.h>
+#include <string.h>
+
+///
+// Defines
+//
+#define ES_PI (3.14159265f)
+
+//////////////////////////////////////////////////////////////////
+//
+// Private Functions
+//
+//
+
+
+
+//////////////////////////////////////////////////////////////////
+//
+// Public Functions
+//
+//
+
+//
+/// \brief Generates geometry for a sphere. Allocates memory for the vertex data and stores
+/// the results in the arrays. Generate index list for a TRIANGLE_STRIP
+/// \param numSlices The number of slices in the sphere
+/// \param vertices If not NULL, will contain array of float3 positions
+/// \param normals If not NULL, will contain array of float3 normals
+/// \param texCoords If not NULL, will contain array of float2 texCoords
+/// \param indices If not NULL, will contain the array of indices for the triangle strip
+/// \return The number of indices required for rendering the buffers (the number of indices stored in the indices array
+/// if it is not NULL ) as a GL_TRIANGLE_STRIP
+//
+int ESUTIL_API esGenSphere ( int numSlices, float radius, GLfloat **vertices, GLfloat **normals,
+ GLfloat **texCoords, GLuint **indices )
+{
+ int i;
+ int j;
+ int numParallels = numSlices / 2;
+ int numVertices = ( numParallels + 1 ) * ( numSlices + 1 );
+ int numIndices = numParallels * numSlices * 6;
+ float angleStep = (2.0f * ES_PI) / ((float) numSlices);
+
+ // Allocate memory for buffers
+ if ( vertices != NULL )
+ *vertices = malloc ( sizeof(GLfloat) * 3 * numVertices );
+
+ if ( normals != NULL )
+ *normals = malloc ( sizeof(GLfloat) * 3 * numVertices );
+
+ if ( texCoords != NULL )
+ *texCoords = malloc ( sizeof(GLfloat) * 2 * numVertices );
+
+ if ( indices != NULL )
+ *indices = malloc ( sizeof(GLuint) * numIndices );
+
+ for ( i = 0; i < numParallels + 1; i++ )
+ {
+ for ( j = 0; j < numSlices + 1; j++ )
+ {
+ int vertex = ( i * (numSlices + 1) + j ) * 3;
+
+ if ( vertices )
+ {
+ (*vertices)[vertex + 0] = radius * sinf ( angleStep * (float)i ) *
+ sinf ( angleStep * (float)j );
+ (*vertices)[vertex + 1] = radius * cosf ( angleStep * (float)i );
+ (*vertices)[vertex + 2] = radius * sinf ( angleStep * (float)i ) *
+ cosf ( angleStep * (float)j );
+ }
+
+ if ( normals )
+ {
+ (*normals)[vertex + 0] = (*vertices)[vertex + 0] / radius;
+ (*normals)[vertex + 1] = (*vertices)[vertex + 1] / radius;
+ (*normals)[vertex + 2] = (*vertices)[vertex + 2] / radius;
+ }
+
+ if ( texCoords )
+ {
+ int texIndex = ( i * (numSlices + 1) + j ) * 2;
+ (*texCoords)[texIndex + 0] = (float) j / (float) numSlices;
+ (*texCoords)[texIndex + 1] = ( 1.0f - (float) i ) / (float) (numParallels - 1 );
+ }
+ }
+ }
+
+ // Generate the indices
+ if ( indices != NULL )
+ {
+ GLuint *indexBuf = (*indices);
+ for ( i = 0; i < numParallels ; i++ )
+ {
+ for ( j = 0; j < numSlices; j++ )
+ {
+ *indexBuf++ = i * ( numSlices + 1 ) + j;
+ *indexBuf++ = ( i + 1 ) * ( numSlices + 1 ) + j;
+ *indexBuf++ = ( i + 1 ) * ( numSlices + 1 ) + ( j + 1 );
+
+ *indexBuf++ = i * ( numSlices + 1 ) + j;
+ *indexBuf++ = ( i + 1 ) * ( numSlices + 1 ) + ( j + 1 );
+ *indexBuf++ = i * ( numSlices + 1 ) + ( j + 1 );
+ }
+ }
+ }
+
+ return numIndices;
+}
+
+//
+/// \brief Generates geometry for a cube. Allocates memory for the vertex data and stores
+/// the results in the arrays. Generate index list for a TRIANGLES
+/// \param scale The size of the cube, use 1.0 for a unit cube.
+/// \param vertices If not NULL, will contain array of float3 positions
+/// \param normals If not NULL, will contain array of float3 normals
+/// \param texCoords If not NULL, will contain array of float2 texCoords
+/// \param indices If not NULL, will contain the array of indices for the triangle strip
+/// \return The number of indices required for rendering the buffers (the number of indices stored in the indices array
+/// if it is not NULL ) as a GL_TRIANGLE_STRIP
+//
+int ESUTIL_API esGenCube ( float scale, GLfloat **vertices, GLfloat **normals,
+ GLfloat **texCoords, GLuint **indices )
+{
+ int i;
+ int numVertices = 24;
+ int numIndices = 36;
+
+ GLfloat cubeVerts[] =
+ {
+ -0.5f, -0.5f, -0.5f,
+ -0.5f, -0.5f, 0.5f,
+ 0.5f, -0.5f, 0.5f,
+ 0.5f, -0.5f, -0.5f,
+ -0.5f, 0.5f, -0.5f,
+ -0.5f, 0.5f, 0.5f,
+ 0.5f, 0.5f, 0.5f,
+ 0.5f, 0.5f, -0.5f,
+ -0.5f, -0.5f, -0.5f,
+ -0.5f, 0.5f, -0.5f,
+ 0.5f, 0.5f, -0.5f,
+ 0.5f, -0.5f, -0.5f,
+ -0.5f, -0.5f, 0.5f,
+ -0.5f, 0.5f, 0.5f,
+ 0.5f, 0.5f, 0.5f,
+ 0.5f, -0.5f, 0.5f,
+ -0.5f, -0.5f, -0.5f,
+ -0.5f, -0.5f, 0.5f,
+ -0.5f, 0.5f, 0.5f,
+ -0.5f, 0.5f, -0.5f,
+ 0.5f, -0.5f, -0.5f,
+ 0.5f, -0.5f, 0.5f,
+ 0.5f, 0.5f, 0.5f,
+ 0.5f, 0.5f, -0.5f,
+ };
+
+ GLfloat cubeNormals[] =
+ {
+ 0.0f, -1.0f, 0.0f,
+ 0.0f, -1.0f, 0.0f,
+ 0.0f, -1.0f, 0.0f,
+ 0.0f, -1.0f, 0.0f,
+ 0.0f, 1.0f, 0.0f,
+ 0.0f, 1.0f, 0.0f,
+ 0.0f, 1.0f, 0.0f,
+ 0.0f, 1.0f, 0.0f,
+ 0.0f, 0.0f, -1.0f,
+ 0.0f, 0.0f, -1.0f,
+ 0.0f, 0.0f, -1.0f,
+ 0.0f, 0.0f, -1.0f,
+ 0.0f, 0.0f, 1.0f,
+ 0.0f, 0.0f, 1.0f,
+ 0.0f, 0.0f, 1.0f,
+ 0.0f, 0.0f, 1.0f,
+ -1.0f, 0.0f, 0.0f,
+ -1.0f, 0.0f, 0.0f,
+ -1.0f, 0.0f, 0.0f,
+ -1.0f, 0.0f, 0.0f,
+ 1.0f, 0.0f, 0.0f,
+ 1.0f, 0.0f, 0.0f,
+ 1.0f, 0.0f, 0.0f,
+ 1.0f, 0.0f, 0.0f,
+ };
+
+ GLfloat cubeTex[] =
+ {
+ 0.0f, 0.0f,
+ 0.0f, 1.0f,
+ 1.0f, 1.0f,
+ 1.0f, 0.0f,
+ 1.0f, 0.0f,
+ 1.0f, 1.0f,
+ 0.0f, 1.0f,
+ 0.0f, 0.0f,
+ 0.0f, 0.0f,
+ 0.0f, 1.0f,
+ 1.0f, 1.0f,
+ 1.0f, 0.0f,
+ 0.0f, 0.0f,
+ 0.0f, 1.0f,
+ 1.0f, 1.0f,
+ 1.0f, 0.0f,
+ 0.0f, 0.0f,
+ 0.0f, 1.0f,
+ 1.0f, 1.0f,
+ 1.0f, 0.0f,
+ 0.0f, 0.0f,
+ 0.0f, 1.0f,
+ 1.0f, 1.0f,
+ 1.0f, 0.0f,
+ };
+
+ // Allocate memory for buffers
+ if ( vertices != NULL )
+ {
+ *vertices = malloc ( sizeof(GLfloat) * 3 * numVertices );
+ memcpy( *vertices, cubeVerts, sizeof( cubeVerts ) );
+ for ( i = 0; i < numVertices * 3; i++ )
+ {
+ (*vertices)[i] *= scale;
+ }
+ }
+
+ if ( normals != NULL )
+ {
+ *normals = malloc ( sizeof(GLfloat) * 3 * numVertices );
+ memcpy( *normals, cubeNormals, sizeof( cubeNormals ) );
+ }
+
+ if ( texCoords != NULL )
+ {
+ *texCoords = malloc ( sizeof(GLfloat) * 2 * numVertices );
+ memcpy( *texCoords, cubeTex, sizeof( cubeTex ) ) ;
+ }
+
+
+ // Generate the indices
+ if ( indices != NULL )
+ {
+ GLuint cubeIndices[] =
+ {
+ 0, 2, 1,
+ 0, 3, 2,
+ 4, 5, 6,
+ 4, 6, 7,
+ 8, 9, 10,
+ 8, 10, 11,
+ 12, 15, 14,
+ 12, 14, 13,
+ 16, 17, 18,
+ 16, 18, 19,
+ 20, 23, 22,
+ 20, 22, 21
+ };
+
+ *indices = malloc ( sizeof(GLuint) * numIndices );
+ memcpy( *indices, cubeIndices, sizeof( cubeIndices ) );
+ }
+
+ return numIndices;
+}
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