int ZQuadTree::_IsInFrustum(CGeoMapData &pHeightMap, Point &bottomLeft, CFrustum& pFrustum)
{
bool b[4];
bool bInSphere;
bInSphere = pFrustum.SphereInFrustum(bottomLeft.x + m_nCenter.x, bottomLeft.y + m_nCenter.y, 0, m_fRadius);
if(!bInSphere) return FRUSTUM_OUT;
b[0] = pFrustum.PointInFrustum(bottomLeft.x + m_nCorner[0].x, bottomLeft.y + m_nCorner[0].y, 0);
b[1] = pFrustum.PointInFrustum(bottomLeft.x + m_nCorner[1].x, bottomLeft.y + m_nCorner[1].y, 0);
b[2] = pFrustum.PointInFrustum(bottomLeft.x + m_nCorner[2].x, bottomLeft.y + m_nCorner[2].y, 0);
b[3] = pFrustum.PointInFrustum(bottomLeft.x + m_nCorner[3].x, bottomLeft.y + m_nCorner[3].y, 0);
if(b[0] + b[1] + b[2] + b[3] == 4)
return FRUSTUM_COMPLETELY_IN;
return FRUSTUM_PRTIALLY_IN;
}
void RenderScene()
{
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
int spheresRendered = 0; // This will hold how many spheres are being rendered
char strText[255]= {0}; // This will hold the window title info
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
glLoadIdentity(); // Reset The matrix
// Give OpenGL our camera position
g_Camera.Look();
// We don't need to calculate this every frame, only when the camera view changes.
// I just did it every frame anyway. In this case it isn't a big deal.
g_Frustum.CalculateFrustum(); // Calculate the frustum each frame
// If you are unfamiliar with Quadrics, see the tutorial on Quadrics at www.GameTutorials.com.
// They basically allow you to draw circles and cylinders fast and easily.
GLUquadricObj *pObj = gluNewQuadric(); // Get a Quadric off the stack
// Loop through all of our allowed spheres and render them to the screen if in the frustum.
for(int i = 0; i < g_MaxSpheres; i++) // g_MaxSpheres varies.
{
g_Spheres[i].zPos += SPHERE_SPEED; // Increase the Z position of the sphere.
// Below we check if the sphere needs to be draw or not. If g_bIgnoreFrustum is TRUE,
// it draws it regardless (which is SLOOOooOoW). We just pass in the (X, Y, Z)
// and the radius of the sphere to find out if it is inside of the frustum.
if(g_bIgnoreFrustum || g_Frustum.SphereInFrustum(g_Spheres[i].xPos, g_Spheres[i].yPos, g_Spheres[i].zPos, g_Spheres[i].radius))
{
// Set the sphere's color
glColor3ub(g_Spheres[i].r, g_Spheres[i].g, g_Spheres[i].b);
// Create a new scope before positiong the sphere so we don't effect the other spheres.
glPushMatrix();
// Position the sphere on the screen at it's XYZ position.
glTranslatef(g_Spheres[i].xPos, g_Spheres[i].yPos, g_Spheres[i].zPos);
// Create a sphere with the desired radius chosen in the beginning.
gluSphere(pObj, g_Spheres[i].radius, 20, 20); // Draw the sphere with a radius of 0.5
glPopMatrix(); // Close the scope of this matrix
spheresRendered++; // Increase the amount of spheres rendered
}
// Here we check to see if the sphere went out of our range,
// If so, we need to set it back again with a new random position.
if(g_Spheres[i].zPos > MAX_DISTANCE) {
// Give the sphere a new random position back in the beginning.
g_Spheres[i].xPos = (rand() % (MAX_DISTANCE * 10)) * 0.1f;
g_Spheres[i].yPos = (rand() % (MAX_DISTANCE * 10)) * 0.1f;
g_Spheres[i].zPos = -MAX_DISTANCE; // Send it to the back again.
// Give a 50/50 chance for the sphere to be to the left/right or above/below the XY axis.
// This is because we are centered at the origin
if(rand() % 2) g_Spheres[i].xPos = -g_Spheres[i].xPos;
if(rand() % 2) g_Spheres[i].yPos = -g_Spheres[i].yPos;
}
}
// Since I didn't want to add more code for a rendered font, I decided to just
// render the frustum information in the title bar of the window.
// The information tells you how many spheres were rendered and out of how many.
// Use +/- to increase and decrease the max spheres tested.
sprintf(strText, "www.GameTutorials.com - Spheres Rendered: %d / %d", spheresRendered, g_MaxSpheres);
SetWindowText(g_hWnd, strText); // Change the window title bar
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
SwapBuffers(g_hDC); // Swap the backbuffers to the foreground
gluDeleteQuadric(pObj); // Free the Quadric
}
