//Set up variables
bool DemoInit()
{
if(!window.Init("Metaballs", 512, 512, 32, 24, 8, WINDOWED_SCREEN))
return 0; //quit if not created
//set up grid
if(!cubeGrid.CreateMemory())
return false;
if(!cubeGrid.Init(gridSize))
return false;
//set up metaballs
for(int i=0; i<numMetaballs; i++)
metaballs[i].Init(VECTOR3D(0.0f, 0.0f, 0.0f), 5.0f+float(i));
//Set Up Colors
diffuseColors[0].Set(0.345f, 0.843f, 0.902f, 1.0f);
diffuseColors[1].Set(0.047f, 0.839f, 0.271f, 1.0f);
diffuseColors[2].Set(0.976f, 0.213f, 0.847f, 1.0f);
//reset timer for start
timer.Reset();
return true;
}
void drawMetaball(int numMetaballs,const vector< vector<float> >& balls)
{
const int minGridSize = 10;
int gridSize = 30;
float threshold = 1.0f;
CUBE_GRID cubeGrid;
METABALL* metaballs = new METABALL[numMetaballs];
for (int i = 0; i<numMetaballs; i++)
metaballs[i].Init(VECTOR3D(balls[i][0], balls[i][1], balls[i][2]), balls[i][3] * balls[i][3]);
//init marching cube
cubeGrid.CreateMemory();
cubeGrid.Init(gridSize);
for (int i = 0; i<cubeGrid.numVertices; i++)
{
cubeGrid.vertices[i].value = 0.0f;
cubeGrid.vertices[i].normal.LoadZero();
}
VECTOR3D ballToPoint;
float squaredRadius;
VECTOR3D ballPosition;
float normalScale;
for (int i = 0; i<numMetaballs; i++)
{
squaredRadius = metaballs[i].squaredRadius;
ballPosition = metaballs[i].position;
//VC++6 standard does not inline functions
//by inlining these maually, in this performance-critical area,
//almost a 100% increase in speed is found
for (int j = 0; j<cubeGrid.numVertices; j++)
{
//ballToPoint=cubeGrid.vertices[j].position-ballPosition;
ballToPoint.x = cubeGrid.vertices[j].position.x - ballPosition.x;
ballToPoint.y = cubeGrid.vertices[j].position.y - ballPosition.y;
ballToPoint.z = cubeGrid.vertices[j].position.z - ballPosition.z;
//get squared distance from ball to point
//float squaredDistance=ballToPoint.GetSquaredLength();
float squaredDistance = ballToPoint.x*ballToPoint.x +
ballToPoint.y*ballToPoint.y +
ballToPoint.z*ballToPoint.z;
if (squaredDistance == 0.0f)
squaredDistance = 0.0001f;
//value = r^2/d^2
cubeGrid.vertices[j].value += squaredRadius / squaredDistance;
//normal = (r^2 * v)/d^4
normalScale = squaredRadius / (squaredDistance*squaredDistance);
//cubeGrid.vertices[j].normal+=ballToPoint*normalScale;
cubeGrid.vertices[j].normal.x += ballToPoint.x*normalScale;
cubeGrid.vertices[j].normal.y += ballToPoint.y*normalScale;
cubeGrid.vertices[j].normal.z += ballToPoint.z*normalScale;
}
}
//hints
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
//need to normalize!
glEnable(GL_NORMALIZE);
glEnable(GL_CULL_FACE);
cubeGrid.DrawSurface(threshold);
glDisable(GL_CULL_FACE);
cubeGrid.FreeMemory();
delete[] metaballs;
}
