// Divides the game arena into 4 quadrants and call initialize for each of them
void board::initializeBoard(){
int ratio = 10;
initializeQuadrant(leftTop, 0, 0, ratio);
initializeQuadrant(rightTop, 500, 0, ratio);
initializeQuadrant(leftBottom, 0, 500, ratio);
initializeQuadrant(rightBottom, 500, 500, ratio);
}
void initializeQuadtree(QuadTree* quadtree, const Box2D& worldBounds, unsigned int depth, unsigned int maxResultsPerQuery, unsigned int maxQuadrants, Quadrant* quadrants, QuadrantEdges* quadrantEdges)
{
quadtree->worldBounds = worldBounds;
quadtree->maxDepth = depth;
quadtree->maxResultsPerQuery = maxResultsPerQuery;
quadtree->maxQuadrants = maxQuadrants;
quadtree->quadrants = quadrants;
quadtree->quadrantsEdges = quadrantEdges;
quadtree->numQuadrantEdges = 0;
#ifdef _DEBUG
quadtree->numCollisionChecks = 0;
quadtree->maxEdgesPerQuadrantInUse = 0;
quadtree->maxResultsPerQueryInUse = 0;
#endif
quadtree->totalNumQuadrants = 0;
for (unsigned int i = 0; i < quadtree->maxDepth; i++)
{
unsigned int numQuadrants = (unsigned int)pow(4.0f, (int)i);
if (i == quadtree->maxDepth - 1)
{
quadtree->numLeafQuadrants = numQuadrants;
}
quadtree->totalNumQuadrants += numQuadrants;
}
initializeQuadrant(quadtree, worldBounds);
}
void initializeQuadrant(QuadTree* quadtree, const Box2D& quadrantBounds, unsigned int depth, unsigned int index, unsigned int offset, unsigned int levelWidth)
{
unsigned int i = offset + index;
// FIXME: checking boundaries
if (i >= quadtree->maxQuadrants)
{
throw std::exception("max. quadrants overflow");
}
Quadrant& quadrant = quadtree->quadrants[i];
quadrant.depth = depth;
quadrant.bounds = quadrantBounds;
if (depth == quadtree->maxDepth - 1) // leaf
{
quadrant.edges = quadtree->numQuadrantEdges++;
return;
}
unsigned int baseIndex = (index * 4);
unsigned int newOffset = offset + levelWidth;
unsigned int newLevelWidth = levelWidth * 4;
unsigned int newDepth = depth + 1;
vml_vec2 subQuadrantSize = quadrantBounds.getExtents() / 2.0f;
for (unsigned int y = 0, i = 0; y < 2; y++)
{
float subQuadrantY = quadrantBounds.min.y + ((float)y * subQuadrantSize.y);
for (unsigned int x = 0; x < 2; x++, i++)
{
initializeQuadrant(quadtree, Box2D(quadrantBounds.min.x + ((float)x * subQuadrantSize.x), subQuadrantY, subQuadrantSize.x, subQuadrantSize.y), newDepth, baseIndex + i, newOffset, newLevelWidth);
}
}
}
