+static void fghCone( double base, double height, GLint slices, GLint stacks, GLboolean useWireMode )
+{
+ int i,j,idx, nVert;
+ GLfloat *vertices, *normals;
+
+ if (slices * stacks > 65535)
+ fgWarning("fghCone: too many slices or stacks requested, indices will wrap");
+
+ /* Generate vertices and normals */
+ fghGenerateCone((GLfloat)base,(GLfloat)height,slices,stacks,&vertices,&normals,&nVert);
+
+ if (nVert==0)
+ /* nothing to draw */
+ return;
+
+ if (useWireMode)
+ {
+ GLushort *sliceIdx, *stackIdx;
+ /* First, generate vertex index arrays for drawing with glDrawElements
+ * We have a bunch of line_loops to draw for each stack, and a
+ * bunch for each slice.
+ */
+
+ stackIdx = malloc(slices*(stacks+1)*sizeof(GLushort));
+ sliceIdx = malloc(slices*2 *sizeof(GLushort));
+ if (!(stackIdx) || !(sliceIdx))
+ {
+ free(stackIdx);
+ free(sliceIdx);
+ fgError("Failed to allocate memory in fghGenerateCone");
+ }
+
+ /* generate for each stack */
+ for (i=0,idx=0; i<stacks+1; i++)
+ {
+ GLushort offset = 1+i*slices; /* start at 1 (0 is top vertex), and we advance one stack down as we go along */
+ for (j=0; j<slices; j++, idx++)
+ {
+ stackIdx[idx] = offset+j;
+ }
+ }
+
+ /* generate for each slice */
+ for (i=0,idx=0; i<slices; i++)
+ {
+ GLushort offset = 1+i; /* start at 1 (0 is top vertex), and we advance one slice as we go along */
+ sliceIdx[idx++] = offset;
+ sliceIdx[idx++] = offset+stacks*slices;
+ }
+
+ /* draw */
+ glEnableClientState(GL_VERTEX_ARRAY);
+ glEnableClientState(GL_NORMAL_ARRAY);
+
+ glVertexPointer(3, GL_FLOAT, 0, vertices);
+ glNormalPointer(GL_FLOAT, 0, normals);
+ /*draw slices*/
+ glDrawElements(GL_LINES,slices*2,GL_UNSIGNED_SHORT,sliceIdx);
+ /*draw stacks*/
+ for (i=0; i<stacks; i++)
+ glDrawElements(GL_LINE_LOOP, slices,GL_UNSIGNED_SHORT,stackIdx+i*slices);
+
+ glDisableClientState(GL_VERTEX_ARRAY);
+ glDisableClientState(GL_NORMAL_ARRAY);
+
+ /* cleanup allocated memory */
+ free(sliceIdx);
+ free(stackIdx);
+ }
+ else
+ {
+ /* First, generate vertex index arrays for drawing with glDrawElements
+ * All stacks, including top and bottom are covered with a triangle
+ * strip.
+ */
+ GLushort *stripIdx;
+ /* Create index vector */
+ GLushort offset;
+
+ /* Allocate buffers for indices, bail out if memory allocation fails */
+ stripIdx = malloc((slices+1)*2*(stacks+1)*sizeof(GLushort));
+ if (!(stripIdx))
+ {
+ free(stripIdx);
+ fgError("Failed to allocate memory in fghGenerateCone");
+ }
+
+ /* top stack */
+ for (j=0, idx=0; j<slices; j++, idx+=2)
+ {
+ stripIdx[idx ] = 0;
+ stripIdx[idx+1] = j+1; /* 0 is top vertex, 1 is first for first stack */
+ }
+ stripIdx[idx ] = 0; /* repeat first slice's idx for closing off shape */
+ stripIdx[idx+1] = 1;
+ idx+=2;
+
+ /* middle stacks: */
+ /* Strip indices are relative to first index belonging to strip, NOT relative to first vertex/normal pair in array */
+ for (i=0; i<stacks; i++, idx+=2)
+ {
+ offset = 1+i*slices; /* triangle_strip indices start at 1 (0 is top vertex), and we advance one stack down as we go along */
+ for (j=0; j<slices; j++, idx+=2)
+ {
+ stripIdx[idx ] = offset+j;
+ stripIdx[idx+1] = offset+j+slices;
+ }
+ stripIdx[idx ] = offset; /* repeat first slice's idx for closing off shape */
+ stripIdx[idx+1] = offset+slices;
+ }
+
+ /* draw */
+ glEnableClientState(GL_VERTEX_ARRAY);
+ glEnableClientState(GL_NORMAL_ARRAY);
+
+ glVertexPointer(3, GL_FLOAT, 0, vertices);
+ glNormalPointer(GL_FLOAT, 0, normals);
+ /*draw stacks*/
+ for (i=0; i<stacks+1; i++)
+ glDrawElements(GL_TRIANGLE_STRIP,(slices+1)*2,GL_UNSIGNED_SHORT,stripIdx+i*(slices+1)*2);
+
+ glDisableClientState(GL_VERTEX_ARRAY);
+ glDisableClientState(GL_NORMAL_ARRAY);
+
+ /* cleanup allocated memory */
+ free(stripIdx);
+ }
+
+ /* cleanup allocated memory */
+ free(vertices);
+ free(normals);
+}