void COctree::CreateNode(CVector3 *pVertices, int numberOfVerts, CVector3 vCenter, float width)
{
// This is our main function that creates the octree. We will recurse through
// this function until we finish subdividing. Either this will be because we
// subdivided too many levels or we divided all of the triangles up.
// Create a variable to hold the number of triangles
int numberOfTriangles = numberOfVerts / 3;
// Initialize this node's center point. Now we know the center of this node.
m_vCenter = vCenter;
// Initialize this nodes cube width. Now we know the width of this current node.
m_Width = width;
// Add the current node to our debug rectangle list so we can visualize it.
// We can now see this node visually as a cube when we render the rectangles.
// Since it's a cube we pass in the width for width, height and depth.
g_Debug.AddDebugRectangle(vCenter, width, width, width);
// Check if we have too many triangles in this node and we haven't subdivided
// above our max subdivisions. If so, then we need to break this node into
// 8 more nodes (hence the word OCTree). Both must be true to divide this node.
if( (numberOfTriangles > g_MaxTriangles) && (g_CurrentSubdivision < g_MaxSubdivisions) )
{
// Since we need to subdivide more we set the divided flag to true.
// This let's us know that this node does NOT have any vertices assigned to it,
// but nodes that perhaps have vertices stored in them (Or their nodes, etc....)
// We will querey this variable when we are drawing the octree.
m_bSubDivided = true;
// Create a list for each new node to store if a triangle should be stored in it's
// triangle list. For each index it will be a true or false to tell us if that triangle
// is in the cube of that node. Below we check every point to see where it's
// position is from the center (I.E. if it's above the center, to the left and
// back it's the TOP_LEFT_BACK node). Depending on the node we set the pList
// index to true. This will tell us later which triangles go to which node.
// You might catch that this way will produce doubles in some nodes. Some
// triangles will intersect more than 1 node right? We won't split the triangles
// in this tutorial just to keep it simple, but the next tutorial we will.
// Create the list of booleans for each triangle index
vector<bool> pList1(numberOfTriangles); // TOP_LEFT_FRONT node list
vector<bool> pList2(numberOfTriangles); // TOP_LEFT_BACK node list
vector<bool> pList3(numberOfTriangles); // TOP_RIGHT_BACK node list
vector<bool> pList4(numberOfTriangles); // TOP_RIGHT_FRONT node list
vector<bool> pList5(numberOfTriangles); // BOTTOM_LEFT_FRONT node list
vector<bool> pList6(numberOfTriangles); // BOTTOM_LEFT_BACK node list
vector<bool> pList7(numberOfTriangles); // BOTTOM_RIGHT_BACK node list
vector<bool> pList8(numberOfTriangles); // BOTTOM_RIGHT_FRONT node list
// Create this variable to cut down the thickness of the code below (easier to read)
CVector3 vCtr = vCenter;
// Go through all of the vertices and check which node they belong too. The way
// we do this is use the center of our current node and check where the point
// lies in relationship to the center. For instance, if the point is
// above, left and back from the center point it's the TOP_LEFT_BACK node.
// You'll see we divide by 3 because there are 3 points in a triangle.
// If the vertex index 0 and 1 are in a node, 0 / 3 and 1 / 3 is 0 so it will
// just set the 0'th index to TRUE twice, which doesn't hurt anything. When
// we get to the 3rd vertex index of pVertices[] it will then be checking the
// 1st index of the pList*[] array. We do this because we want a list of the
// triangles in the node, not the vertices.
for(int i = 0; i < numberOfVerts; i++)
{
// Create some variables to cut down the thickness of the code (easier to read)
CVector3 vPoint = pVertices[i];
// Check if the point lines within the TOP LEFT FRONT node
if( (vPoint.x <= vCtr.x) && (vPoint.y >= vCtr.y) && (vPoint.z >= vCtr.z) )
pList1[i / 3] = true;
// Check if the point lines within the TOP LEFT BACK node
if( (vPoint.x <= vCtr.x) && (vPoint.y >= vCtr.y) && (vPoint.z <= vCtr.z) )
pList2[i / 3] = true;
// Check if the point lines within the TOP RIGHT BACK node
if( (vPoint.x >= vCtr.x) && (vPoint.y >= vCtr.y) && (vPoint.z <= vCtr.z) )
pList3[i / 3] = true;
// Check if the point lines within the TOP RIGHT FRONT node
if( (vPoint.x >= vCtr.x) && (vPoint.y >= vCtr.y) && (vPoint.z >= vCtr.z) )
pList4[i / 3] = true;
// Check if the point lines within the BOTTOM LEFT FRONT node
if( (vPoint.x <= vCtr.x) && (vPoint.y <= vCtr.y) && (vPoint.z >= vCtr.z) )
pList5[i / 3] = true;
// Check if the point lines within the BOTTOM LEFT BACK node
if( (vPoint.x <= vCtr.x) && (vPoint.y <= vCtr.y) && (vPoint.z <= vCtr.z) )
pList6[i / 3] = true;
// Check if the point lines within the BOTTOM RIGHT BACK node
if( (vPoint.x >= vCtr.x) && (vPoint.y <= vCtr.y) && (vPoint.z <= vCtr.z) )
pList7[i / 3] = true;
// Check if the point lines within the BOTTOM RIGHT FRONT node
if( (vPoint.x >= vCtr.x) && (vPoint.y <= vCtr.y) && (vPoint.z >= vCtr.z) )
pList8[i / 3] = true;
}
// Here we create a variable for each list that holds how many triangles
// were found for each of the 8 subdivided nodes.
int triCount1 = 0;
int triCount2 = 0;
int triCount3 = 0;
int triCount4 = 0;
int triCount5 = 0;
int triCount6 = 0;
int triCount7 = 0;
int triCount8 = 0;
// Go through each of the lists and increase the triangle count for each node.
for(int i = 0; i < numberOfTriangles; i++)
{
// Increase the triangle count for each node that has a "true" for the index i.
if(pList1[i]) triCount1++;
if(pList2[i]) triCount2++;
if(pList3[i]) triCount3++;
if(pList4[i]) triCount4++;
if(pList5[i]) triCount5++;
if(pList6[i]) triCount6++;
if(pList7[i]) triCount7++;
if(pList8[i]) triCount8++;
}
// Next we do the dirty work. We need to set up the new nodes with the triangles
// that are assigned to each node, along with the new center point of the node.
// Through recursion we subdivide this node into 8 more nodes.
// Create the subdivided nodes if necessary and then recurse through them.
// The information passed into CreateNewNode() are essential for creating the
// new nodes. We pass the 8 ID's in so it knows how to calculate it's new center.
CreateNewNode(pVertices, pList1, numberOfVerts, vCenter, width, triCount1, TOP_LEFT_FRONT);
CreateNewNode(pVertices, pList2, numberOfVerts, vCenter, width, triCount2, TOP_LEFT_BACK);
CreateNewNode(pVertices, pList3, numberOfVerts, vCenter, width, triCount3, TOP_RIGHT_BACK);
CreateNewNode(pVertices, pList4, numberOfVerts, vCenter, width, triCount4, TOP_RIGHT_FRONT);
CreateNewNode(pVertices, pList5, numberOfVerts, vCenter, width, triCount5, BOTTOM_LEFT_FRONT);
CreateNewNode(pVertices, pList6, numberOfVerts, vCenter, width, triCount6, BOTTOM_LEFT_BACK);
CreateNewNode(pVertices, pList7, numberOfVerts, vCenter, width, triCount7, BOTTOM_RIGHT_BACK);
CreateNewNode(pVertices, pList8, numberOfVerts, vCenter, width, triCount8, BOTTOM_RIGHT_FRONT);
}
else
{
// If we get here we must either be subdivided past our max level, or our triangle
// count went below the minimum amount of triangles so we need to store them.
// Assign the vertices to this node since we reached the end node.
// This will be the end node that actually gets called to be drawn.
// We just pass in the vertices and vertex count to be assigned to this node.
AssignVerticesToNode(pVertices, numberOfVerts);
}
}
void COctree::CreateNode(t3DModel *pWorld, int numberOfTriangles, CVector3 vCenter, float width)
{
// Initialize this node's center point. Now we know the center of this node.
m_vCenter = vCenter;
// Initialize this nodes cube width. Now we know the width of this current node.
m_Width = width;
// Add the current node to our debug rectangle list so we can visualize it.
g_Debug.AddDebugRectangle(vCenter, width, width, width);
// Check if we have too many triangles in this node and we haven't subdivided
// above our max subdivisions. If so, then we need to break this node into
// 8 more nodes (hence the word OCTree). Both must be true to divide this node.
if( (numberOfTriangles > g_MaxTriangles) && (g_CurrentSubdivision < g_MaxSubdivisions) )
{
// Since we need to subdivide more we set the divided flag to true.
m_bSubDivided = true;
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
// This function pretty much stays the same, except a small twist because
// we are dealing with multiple objects for the scene, not just an array of vertices.
// In the previous tutorials, we used a vector<> of booleans, but now we use our
// tFaceList to store a vector of booleans for each object.
// Create the list of tFaceLists for each child node
vector<tFaceList> pList1(pWorld->numOfObjects); // TOP_LEFT_FRONT node list
vector<tFaceList> pList2(pWorld->numOfObjects); // TOP_LEFT_BACK node list
vector<tFaceList> pList3(pWorld->numOfObjects); // TOP_RIGHT_BACK node list
vector<tFaceList> pList4(pWorld->numOfObjects); // TOP_RIGHT_FRONT node list
vector<tFaceList> pList5(pWorld->numOfObjects); // BOTTOM_LEFT_FRONT node list
vector<tFaceList> pList6(pWorld->numOfObjects); // BOTTOM_LEFT_BACK node list
vector<tFaceList> pList7(pWorld->numOfObjects); // BOTTOM_RIGHT_BACK node list
vector<tFaceList> pList8(pWorld->numOfObjects); // BOTTOM_RIGHT_FRONT node list
// Create this variable to cut down the thickness of the code below (easier to read)
CVector3 vCtr = vCenter;
// Go through every object in the current partition of the world
for(int i = 0; i < pWorld->numOfObjects; i++)
{
// Store a point to the current object
t3DObject *pObject = &(pWorld->pObject[i]);
// Now, we have a face list for each object, for every child node.
// We need to then check every triangle in this current object
// to see if it's in any of the child nodes dimensions. We store a "true" in
// the face list index to tell us if that's the case. This is then used
// in CreateNewNode() to create a new partition of the world for that child node.
// Resize the current face list to be the size of this object's face count
pList1[i].pFaceList.resize(pObject->numOfFaces);
pList2[i].pFaceList.resize(pObject->numOfFaces);
pList3[i].pFaceList.resize(pObject->numOfFaces);
pList4[i].pFaceList.resize(pObject->numOfFaces);
pList5[i].pFaceList.resize(pObject->numOfFaces);
pList6[i].pFaceList.resize(pObject->numOfFaces);
pList7[i].pFaceList.resize(pObject->numOfFaces);
pList8[i].pFaceList.resize(pObject->numOfFaces);
// Go through all the triangles for this object
for(int j = 0; j < pObject->numOfFaces; j++)
{
// Check every vertice in the current triangle to see if it's inside a child node
for(int whichVertex = 0; whichVertex < 3; whichVertex++)
{
// Store the current vertex to be checked against all the child nodes
CVector3 vPoint = pObject->pVerts[pObject->pFaces[j].vertIndex[whichVertex]];
// Check if the point lies within the TOP LEFT FRONT node
if( (vPoint.x <= vCtr.x) && (vPoint.y >= vCtr.y) && (vPoint.z >= vCtr.z) )
pList1[i].pFaceList[j] = true;
// Check if the point lies within the TOP LEFT BACK node
if( (vPoint.x <= vCtr.x) && (vPoint.y >= vCtr.y) && (vPoint.z <= vCtr.z) )
pList2[i].pFaceList[j] = true;
// Check if the point lies within the TOP RIGHT BACK node
if( (vPoint.x >= vCtr.x) && (vPoint.y >= vCtr.y) && (vPoint.z <= vCtr.z) )
pList3[i].pFaceList[j] = true;
// Check if the point lies within the TOP RIGHT FRONT node
if( (vPoint.x >= vCtr.x) && (vPoint.y >= vCtr.y) && (vPoint.z >= vCtr.z) )
pList4[i].pFaceList[j] = true;
// Check if the point lies within the BOTTOM LEFT FRONT node
if( (vPoint.x <= vCtr.x) && (vPoint.y <= vCtr.y) && (vPoint.z >= vCtr.z) )
pList5[i].pFaceList[j] = true;
// Check if the point lies within the BOTTOM LEFT BACK node
if( (vPoint.x <= vCtr.x) && (vPoint.y <= vCtr.y) && (vPoint.z <= vCtr.z) )
pList6[i].pFaceList[j] = true;
// Check if the point lies within the BOTTOM RIGHT BACK node
if( (vPoint.x >= vCtr.x) && (vPoint.y <= vCtr.y) && (vPoint.z <= vCtr.z) )
pList7[i].pFaceList[j] = true;
// Check if the point lines within the BOTTOM RIGHT FRONT node
if( (vPoint.x >= vCtr.x) && (vPoint.y <= vCtr.y) && (vPoint.z >= vCtr.z) )
pList8[i].pFaceList[j] = true;
}
}
// Here we initialize the face count for each list that holds how many triangles
// were found for each of the 8 subdivided nodes.
pList1[i].totalFaceCount = 0; pList2[i].totalFaceCount = 0;
pList3[i].totalFaceCount = 0; pList4[i].totalFaceCount = 0;
pList5[i].totalFaceCount = 0; pList6[i].totalFaceCount = 0;
pList7[i].totalFaceCount = 0; pList8[i].totalFaceCount = 0;
}
// Here we create a variable for each list that holds how many triangles
// were found for each of the 8 subdivided nodes.
int triCount1 = 0; int triCount2 = 0; int triCount3 = 0; int triCount4 = 0;
int triCount5 = 0; int triCount6 = 0; int triCount7 = 0; int triCount8 = 0;
// Go through all of the objects of this current partition
for(i = 0; i < pWorld->numOfObjects; i++)
{
// Go through all of the current objects triangles
for(int j = 0; j < pWorld->pObject[i].numOfFaces; j++)
{
// Increase the triangle count for each node that has a "true" for the index i.
// In other words, if the current triangle is in a child node, add 1 to the count.
// We need to store the total triangle count for each object, but also
// the total for the whole child node. That is why we increase 2 variables.
if(pList1[i].pFaceList[j]) { pList1[i].totalFaceCount++; triCount1++; }
if(pList2[i].pFaceList[j]) { pList2[i].totalFaceCount++; triCount2++; }
if(pList3[i].pFaceList[j]) { pList3[i].totalFaceCount++; triCount3++; }
if(pList4[i].pFaceList[j]) { pList4[i].totalFaceCount++; triCount4++; }
if(pList5[i].pFaceList[j]) { pList5[i].totalFaceCount++; triCount5++; }
if(pList6[i].pFaceList[j]) { pList6[i].totalFaceCount++; triCount6++; }
if(pList7[i].pFaceList[j]) { pList7[i].totalFaceCount++; triCount7++; }
if(pList8[i].pFaceList[j]) { pList8[i].totalFaceCount++; triCount8++; }
}
}
// Next we do the dirty work. We need to set up the new nodes with the triangles
// that are assigned to each node, along with the new center point of the node.
// Through recursion we subdivide this node into 8 more potential nodes.
// Create the subdivided nodes if necessary and then recurse through them.
// The information passed into CreateNewNode() are essential for creating the
// new nodes. We pass the 8 ID's in so it knows how to calculate it's new center.
CreateNewNode(pWorld, pList1, triCount1, vCenter, width, TOP_LEFT_FRONT);
CreateNewNode(pWorld, pList2, triCount2, vCenter, width, TOP_LEFT_BACK);
CreateNewNode(pWorld, pList3, triCount3, vCenter, width, TOP_RIGHT_BACK);
CreateNewNode(pWorld, pList4, triCount4, vCenter, width, TOP_RIGHT_FRONT);
CreateNewNode(pWorld, pList5, triCount5, vCenter, width, BOTTOM_LEFT_FRONT);
CreateNewNode(pWorld, pList6, triCount6, vCenter, width, BOTTOM_LEFT_BACK);
CreateNewNode(pWorld, pList7, triCount7, vCenter, width, BOTTOM_RIGHT_BACK);
CreateNewNode(pWorld, pList8, triCount8, vCenter, width, BOTTOM_RIGHT_FRONT);
}
else
{
// If we get here we must either be subdivided past our max level, or our triangle
// count went below the minimum amount of triangles so we need to store them.
// We pass in the current partition of world data to be assigned to this end node
AssignTrianglesToNode(pWorld, numberOfTriangles);
}
/////// * /////////// * /////////// * NEW * /////// * /////////// * /////////// *
}
