From 57efea40ee805c0916fd176ac0e6cb6fc15cf94a Mon Sep 17 00:00:00 2001
From: Mark Peng <peng.markv@gmail.com>
Date: Mon, 5 Aug 2013 19:52:02 -0700
Subject: [PATCH] Add untested renderHalfCylinder function to GeometryCache/

---
 interface/src/renderer/GeometryCache.cpp | 68 ++++++++++++++++++++++++
 interface/src/renderer/GeometryCache.h   |  2 +
 2 files changed, 70 insertions(+)

diff --git a/interface/src/renderer/GeometryCache.cpp b/interface/src/renderer/GeometryCache.cpp
index 8331a5deb9..07c383c1c1 100644
--- a/interface/src/renderer/GeometryCache.cpp
+++ b/interface/src/renderer/GeometryCache.cpp
@@ -163,3 +163,71 @@ void GeometryCache::renderSquare(int xDivisions, int yDivisions) {
     glBindBuffer(GL_ARRAY_BUFFER, 0);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 }
+
+void GeometryCache::renderHalfCylinder(int slices, int stacks, float radius, float height) {
+    VerticesIndices& vbo = _halfCylinderVBOs[IntPair(slices, stacks)];
+    int vertices = slices * (stacks - 1) + 1;
+    int indices = slices * 2 * 3 * (stacks - 2) + slices * 3;
+    if (vbo.first == 0) {    
+        GLfloat* vertexData = new GLfloat[vertices * 3];
+        GLfloat* vertex = vertexData;
+        for (int i = 0; i < stacks; i++) {
+            float z = i * height / stacks;
+            
+            for (int j = 0; j < slices; j++) {
+                float theta = PIf * j / slices;
+
+                *(vertex++) = sinf(theta) * radius;
+                *(vertex++) = cosf(theta) * radius;
+                *(vertex++) = z;
+            }
+        }
+        
+        glGenBuffers(1, &vbo.first);
+        glBindBuffer(GL_ARRAY_BUFFER, vbo.first);
+        const int BYTES_PER_VERTEX = 3 * sizeof(GLfloat);
+        glBufferData(GL_ARRAY_BUFFER, vertices * BYTES_PER_VERTEX, vertexData, GL_STATIC_DRAW);
+        delete[] vertexData;
+        
+        GLushort* indexData = new GLushort[indices];
+        GLushort* index = indexData;
+        for (int i = 0; i < stacks - 1; i++) {
+            GLushort bottom = i * slices;
+            GLushort top = bottom + slices;
+            for (int j = 0; j < slices; j++) {
+                int next = (j + 1) % slices;
+                
+                *(index++) = bottom + j;
+                *(index++) = top + next;
+                *(index++) = top + j;
+                
+                *(index++) = bottom + j;
+                *(index++) = bottom + next;
+                *(index++) = top + next;
+            }
+        }
+        
+        glGenBuffers(1, &vbo.second);
+        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vbo.second);
+        const int BYTES_PER_INDEX = sizeof(GLushort);
+        glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices * BYTES_PER_INDEX, indexData, GL_STATIC_DRAW);
+        delete[] indexData;
+    
+    } else {
+        glBindBuffer(GL_ARRAY_BUFFER, vbo.first);
+        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vbo.second);
+    }
+    glEnableClientState(GL_VERTEX_ARRAY);
+    glEnableClientState(GL_NORMAL_ARRAY);
+ 
+    glVertexPointer(3, GL_FLOAT, 0, 0);
+    glNormalPointer(GL_FLOAT, 0, 0);
+        
+    glDrawRangeElementsEXT(GL_TRIANGLES, 0, vertices - 1, indices, GL_UNSIGNED_SHORT, 0);
+        
+    glDisableClientState(GL_VERTEX_ARRAY);
+    glDisableClientState(GL_NORMAL_ARRAY);
+    
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
+}
\ No newline at end of file
diff --git a/interface/src/renderer/GeometryCache.h b/interface/src/renderer/GeometryCache.h
index bfce642554..a0764db887 100644
--- a/interface/src/renderer/GeometryCache.h
+++ b/interface/src/renderer/GeometryCache.h
@@ -20,6 +20,7 @@ public:
     
     void renderHemisphere(int slices, int stacks);
     void renderSquare(int xDivisions, int yDivisions);
+    void renderHalfCylinder(int slices, int stacks, float radius, float height);
 
 private:
     
@@ -28,6 +29,7 @@ private:
     
     QHash<IntPair, VerticesIndices> _hemisphereVBOs;
     QHash<IntPair, VerticesIndices> _squareVBOs;
+    QHash<IntPair, VerticesIndices> _halfCylinderVBOs;
 };
 
 #endif /* defined(__interface__GeometryCache__) */