//draw a frame
void RenderFrame()
{
//Clear buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity(); //reset modelview matrix
glEnable(GL_LIGHTING);
glTranslatef(0.0f, 0.0f, -30.0f);
glRotatef((float)timer.GetTime()/30, 1.0f, 0.0f, 1.0f);
cubeGrid.DrawSurface(threshold);
glDisable(GL_LIGHTING);
fpsCounter.Update(); //update frames per second counter
glColor4f(0.0f, 0.0f, 1.0f, 1.0f);
window.StartTextMode();
window.Print(0, 28, "FPS: %.2f", fpsCounter.GetFps()); //print the fps
glColor4f(1.0f, 1.0f, 0.0f, 1.0f);
window.Print(0, 48, "Grid Size: %d", gridSize);
window.Print(0, 68, "%d triangles drawn", cubeGrid.numFacesDrawn);
window.EndTextMode();
glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
if(window.isKeyPressed(VK_F1))
{
window.SaveScreenshot();
window.SetKeyReleased(VK_F1);
}
window.SwapBuffers(); //swap buffers
//check for any opengl errors
window.CheckGLError();
//quit if necessary
if(window.isKeyPressed(VK_ESCAPE))
PostQuitMessage(0);
}
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;
}
