void COctree::DrawOctree(COctree *pNode, t3DModel *pRootWorld)
{
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
// To draw our octree, all that needs to be done is call our display list ID.
// First we want to check if the current node is even in our frustum. If it is,
// we make sure that the node isn't subdivided. We only can draw the end nodes.
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
// Make sure a valid node was passed in, otherwise go back to the last node
if(!pNode) return;
// Check if the current node is in our frustum
if(!g_Frustum.CubeInFrustum(pNode->m_vCenter.x, pNode->m_vCenter.y,
pNode->m_vCenter.z, pNode->m_Width / 2) )
{
return;
}
// Check if this node is subdivided. If so, then we need to recurse and draw it's nodes
if(pNode->IsSubDivided())
{
// Recurse to the bottom of these nodes and draw the end node's vertices
// Like creating the octree, we need to recurse through each of the 8 nodes.
DrawOctree(pNode->m_pOctreeNodes[TOP_LEFT_FRONT], pRootWorld);
DrawOctree(pNode->m_pOctreeNodes[TOP_LEFT_BACK], pRootWorld);
DrawOctree(pNode->m_pOctreeNodes[TOP_RIGHT_BACK], pRootWorld);
DrawOctree(pNode->m_pOctreeNodes[TOP_RIGHT_FRONT], pRootWorld);
DrawOctree(pNode->m_pOctreeNodes[BOTTOM_LEFT_FRONT], pRootWorld);
DrawOctree(pNode->m_pOctreeNodes[BOTTOM_LEFT_BACK], pRootWorld);
DrawOctree(pNode->m_pOctreeNodes[BOTTOM_RIGHT_BACK], pRootWorld);
DrawOctree(pNode->m_pOctreeNodes[BOTTOM_RIGHT_FRONT], pRootWorld);
}
else
{
// Increase the amount of nodes in our viewing frustum (camera's view)
g_TotalNodesDrawn++;
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
// Make sure we have valid data assigned to this node
if(!pNode->m_pWorld) return;
// Call the list with our end node's display list ID
glCallList(pNode->m_DisplayListID);
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
}
}
void COctree::DrawOctree(COctree *pNode)
{
// We should already have the octree created before we call this function.
// This only goes through the nodes that are in our frustum, then renders those
// vertices stored in their end nodes. Before we draw a node we check to
// make sure it is a subdivided node (from m_bSubdivided). If it is, then
// we haven't reaches the end and we need to keep recursing through the tree.
// Once we get to a node that isn't subdivided we draw it's vertices.
// Make sure a valid node was passed in, otherwise go back to the last node
if(!pNode) return;
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
// Before we do any checks with the current node, let's make sure we even need too.
// We want to check if this node's cube is even in our frustum first.
// To do that we pass in our center point of the node and 1/2 it's width to our
// CubeInFrustum() function. This will return "true" if it is inside the frustum
// (camera's view), otherwise return false.
else if(g_Frustum.CubeInFrustum(pNode->m_vCenter.x, pNode->m_vCenter.y,
pNode->m_vCenter.z, pNode->m_Width / 2))
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
// Check if this node is subdivided. If so, then we need to recurse and draw it's nodes
if(pNode->IsSubDivided())
{
// Recurse to the bottom of these nodes and draw the end node's vertices
// Like creating the octree, we need to recurse through each of the 8 nodes.
DrawOctree(pNode->m_pOctreeNodes[TOP_LEFT_FRONT]);
DrawOctree(pNode->m_pOctreeNodes[TOP_LEFT_BACK]);
DrawOctree(pNode->m_pOctreeNodes[TOP_RIGHT_BACK]);
DrawOctree(pNode->m_pOctreeNodes[TOP_RIGHT_FRONT]);
DrawOctree(pNode->m_pOctreeNodes[BOTTOM_LEFT_FRONT]);
DrawOctree(pNode->m_pOctreeNodes[BOTTOM_LEFT_BACK]);
DrawOctree(pNode->m_pOctreeNodes[BOTTOM_RIGHT_BACK]);
DrawOctree(pNode->m_pOctreeNodes[BOTTOM_RIGHT_FRONT]);
}
else
{
// Increase the amount of nodes in our viewing frustum (camera's view)
g_TotalNodesDrawn++;
// Make sure we have valid vertices assigned to this node
if(!pNode->m_pVertices) return;
// Render the world data with triangles
glBegin(GL_TRIANGLES);
// Turn the polygons green
glColor3ub(0, 255, 0);
// Store the vertices in a local pointer to keep code more clean
CVector3 *pVertices = pNode->m_pVertices;
// Go through all of the vertices (the number of triangles * 3)
for(int i = 0; i < pNode->GetTriangleCount() * 3; i += 3)
{
// Before we render the vertices we want to calculate the face normal
// of the current polygon. That way when lighting is turned on we can
// see the definition of the terrain more clearly. In reality you wouldn't do this.
// Here we get a vector from each side of the triangle
CVector3 vVector1 = pVertices[i + 1] - pVertices[i];
CVector3 vVector2 = pVertices[i + 2] - pVertices[i];
// Then we need to get the cross product of those 2 vectors (The normal's direction)
CVector3 vNormal = Cross(vVector1, vVector2);
// Now we normalize the normal so it is a unit vector (length of 1)
vNormal = Normalize(vNormal);
// Pass in the normal for this triangle so we can see better depth in the scene
glNormal3f(vNormal.x, vNormal.y, vNormal.z);
// Render the first point in the triangle
glVertex3f(pVertices[i].x, pVertices[i].y, pVertices[i].z);
// Render the next point in the triangle
glVertex3f(pVertices[i + 1].x, pVertices[i + 1].y, pVertices[i + 1].z);
// Render the last point in the triangle to form the current triangle
glVertex3f(pVertices[i + 2].x, pVertices[i + 2].y, pVertices[i + 2].z);
}
// Quit Drawing
glEnd();
}
}