From 67115ccad44e872c82014f1ab629fc675af01dae Mon Sep 17 00:00:00 2001
From: Philip Rosedale <philip@coffeeandpower.com>
Date: Thu, 21 Feb 2013 11:25:52 -0800
Subject: [PATCH] First commit of 'Death Star' voxel planet

---
 interface/src/VoxelSystem.cpp | 50 ++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 18 deletions(-)

diff --git a/interface/src/VoxelSystem.cpp b/interface/src/VoxelSystem.cpp
index 79c77ff388..d654f71a5e 100644
--- a/interface/src/VoxelSystem.cpp
+++ b/interface/src/VoxelSystem.cpp
@@ -8,6 +8,12 @@
 
 #include "VoxelSystem.h"
 
+
+bool onSphereShell(float radius, float scale, glm::vec3 * position) {
+    float vRadius = glm::length(*position);
+    return ((vRadius + scale/2.0 > radius) && (vRadius - scale/2.0 < radius));
+}
+
 void VoxelSystem::init() {
     root = new Voxel;
 }
@@ -21,42 +27,48 @@ int VoxelSystem::initVoxels(Voxel * voxel, float scale, glm::vec3 * position) {
     int newVoxels = 0;
     if (voxel == NULL) voxel = root;
     averageColor[0] = averageColor[1] = averageColor[2] = 0.0;
+    
+    const float RADIUS = 3.9;
+    
     //
-    //  First, decide whether I should be a leaf node and set/return if so 
+    //  First, randomly decide whether to stop here without recursing for children 
     //
-    if ((randFloat() < 0.1) && (scale < 1.0))
+    if (onSphereShell(RADIUS, scale, position) && (scale < 0.25) && (randFloat() < 0.01))
     {
-        voxel->color.x = voxel->color.y = voxel->color.z = 0.5 + randFloat()*0.5;
+        voxel->color.x = 0.1;
+        voxel->color.y = 0.5 + randFloat()*0.5;
+        voxel->color.z = 0.1;
         for (unsigned char i = 0; i < NUM_CHILDREN; i++) voxel->children[i] = NULL;
         return 0;
     } else {
         // Decide whether to make kids, recurse into them 
         for (unsigned char i = 0; i < NUM_CHILDREN; i++) {
-            if  ((scale > 0.01) && (randFloat() > 0.6))
-            {
-                //  Make a new child
-                voxel->children[i] = new Voxel;
-                newVoxels++;
-                childrenCreated++;
+            if  (scale > 0.01)              {
                 glm::vec3 shift(scale/2.0*((i&4)>>2)-scale/4.0,
                                 scale/2.0*((i&2)>>1)-scale/4.0,
                                 scale/2.0*(i&1)-scale/4.0);
                 *position += shift;
-                newVoxels += initVoxels(voxel->children[i], scale/2.0, position);
+                //  Test to see whether the child is also on edge of sphere
+                if (onSphereShell(RADIUS, scale/2.0, position)) {
+                    voxel->children[i] = new Voxel;
+                    newVoxels++;
+                    childrenCreated++;
+                    newVoxels += initVoxels(voxel->children[i], scale/2.0, position);
+                    averageColor += voxel->children[i]->color;
+                } else voxel->children[i] = NULL;
                 *position -= shift;
-                averageColor += voxel->children[i]->color;
             } else {
                 //  No child made: Set pointer to null, nothing to see here. 
                 voxel->children[i] = NULL;
             }
         }
         if (childrenCreated > 0) {
-            //  If there were children created, set this voxels color to the average of it's children
+            //  If there were children created, the color of this voxel node is average of children
             averageColor *= 1.0/childrenCreated;
             voxel->color = averageColor;
             return newVoxels;
         } else {
-            //  Tested and didn't make any children, so i've still got to be a leaf
+            //  Tested and didn't make any children, so choose my color as a leaf, return
             voxel->color.x = voxel->color.y = voxel->color.z = 0.5 + randFloat()*0.5;
             for (unsigned char i = 0; i < NUM_CHILDREN; i++) voxel->children[i] = NULL;
             return 0;
@@ -65,7 +77,12 @@ int VoxelSystem::initVoxels(Voxel * voxel, float scale, glm::vec3 * position) {
     }
 }
 
-const float RENDER_DISCARD = 0.01;
+//
+//  The Render Discard is the ratio of the size of the voxel to the distance from the camera
+//  at which the voxel will no longer be shown.  Smaller = show more detail.  
+//  
+
+const float RENDER_DISCARD = 0.04;  //0.01;
 
 //
 //  Returns the total number of voxels actually rendered
@@ -83,7 +100,6 @@ int VoxelSystem::render(Voxel * voxel, float scale, glm::vec3 * distance) {
                         scale/2.0*(i&1)-scale/4.0);
         if ((voxel->children[i] != NULL) && (scale / glm::length(*distance) > RENDER_DISCARD)) {
             glTranslatef(shift.x, shift.y, shift.z);
-            //std::cout << "x,y,z: " << shift.x <<  "," << shift.y << "," << shift.z << "\n";
             *distance += shift;
             vRendered += render(voxel->children[i], scale/2.0, distance);
             *distance -= shift;
@@ -94,10 +110,8 @@ int VoxelSystem::render(Voxel * voxel, float scale, glm::vec3 * distance) {
     //  Render this voxel if the children were not rendered 
     if (!renderedChildren)
     {
-        //glColor4f(1,1,1,1);
+        //  This is the place where we need to copy this data to a VBO to make this FAST
         glColor4f(voxel->color.x, voxel->color.y, voxel->color.z, 1.0);
-        //float bright = 1.0 - glm::length(*distance)/20.0;
-        //glColor3f(bright,bright,bright);
         glutSolidCube(scale);
         vRendered++;
     }