# Code archives/3D Graphics - Mesh/CalculateNormals

This code has been declared by its author to be Public Domain code.

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This function calculates both the face and vertex normals for a mesh using a method which does NOT smooth across vertcies that sit at the same location in space. If two faces do not share a vertex, no smoothing will take place. This allows you to more easily build levels which have sharp corners. For exmaple, if you make a cube which has six seperate sides, with no vertcies shared between sides, this function will smooth it properly, whereas the built in function will not. | |||||

Dim Face_NX#(32768) Dim Face_NY#(32768) Dim Face_NZ#(32768) Dim Vertex_ConnectedTris(32768) Dim Vertex_TriList(32768, 32) ; ------------------------------------------------------------------------------------------------------------------- ; This function calculates and sets the normals for a mesh. ; ; Should probably update this so that it can recursively loop through all of an entities children as well. ; ------------------------------------------------------------------------------------------------------------------- Function Calculate_Normals(ThisMesh) ; Loop through all surfaces of the mesh. Surfaces = CountSurfaces(ThisMesh) For LOOP_Surface = 1 To Surfaces Surface_Handle = GetSurface(ThisMesh, LOOP_Surface) ; Reset the number of connected polygons for each vertex. For LoopV = 0 To 32767 Vertex_ConnectedTris(LoopV) = 0 Next ; Loop through all triangles in this surface of the mesh. Tris = CountTriangles(Surface_Handle) For LOOP_Tris = 0 To Tris-1 ; Get the vertices that make up this triangle. Vertex_0 = TriangleVertex(Surface_Handle, LOOP_Tris, 0) Vertex_1 = TriangleVertex(Surface_Handle, LOOP_Tris, 1) Vertex_2 = TriangleVertex(Surface_Handle, LOOP_Tris, 2) ; Adjust the number of triangles each vertex is connected to and ; store this triangle in each vertex's list of triangles it is connected to. ConnectedTris = Vertex_ConnectedTris(Vertex_0) Vertex_TriList(Vertex_0, ConnectedTris) = LOOP_Tris Vertex_ConnectedTris(Vertex_0) = ConnectedTris + 1 ConnectedTris = Vertex_ConnectedTris(Vertex_1) Vertex_TriList(Vertex_1, ConnectedTris) = LOOP_Tris Vertex_ConnectedTris(Vertex_1) = ConnectedTris + 1 ConnectedTris = Vertex_ConnectedTris(Vertex_2) Vertex_TriList(Vertex_2, ConnectedTris) = LOOP_Tris Vertex_ConnectedTris(Vertex_2) = ConnectedTris + 1 ; Calculate the normal for this face. ; Get the corners of this face: Ax# = VertexX#(Surface_Handle, Vertex_0) Ay# = VertexY#(Surface_Handle, Vertex_0) Az# = VertexZ#(Surface_Handle, Vertex_0) Bx# = VertexX#(Surface_Handle, Vertex_1) By# = VertexY#(Surface_Handle, Vertex_1) Bz# = VertexZ#(Surface_Handle, Vertex_1) Cx# = VertexX#(Surface_Handle, Vertex_2) Cy# = VertexY#(Surface_Handle, Vertex_2) Cz# = VertexZ#(Surface_Handle, Vertex_2) ; Triangle 1 ; Get the vectors for two edges of the triangle. Px# = Ax#-Bx# Py# = Ay#-By# Pz# = Az#-Bz# Qx# = Bx#-Cx# Qy# = By#-Cy# Qz# = Bz#-Cz# ; Compute their cross product. Nx# = Py#*Qz# - Pz#*Qy# Ny# = Pz#*Qx# - Px#*Qz# Nz# = Px#*Qy# - Py#*Qx# ; Store the face normal. Face_NX#(LOOP_Tris) = Nx# Face_NY#(LOOP_Tris) = Ny# Face_NZ#(LOOP_Tris) = Nz# Next ; Now that all the face normals for this surface have been calculated, calculate the vertex normals. Vertices = CountVertices(Surface_Handle) For LOOP_Vertices = 0 To Vertices-1 ; Reset this normal. Nx# = 0 Ny# = 0 Nz# = 0 ; Add the normals of all polygons which are connected to this vertex. Polys = Vertex_ConnectedTris(LOOP_Vertices) For LOOP_Polys = 0 To Polys-1 ThisPoly = Vertex_TriList(LOOP_Vertices, LOOP_Polys) Nx# = Nx# + Face_NX#(ThisPoly) Ny# = Ny# + Face_NY#(ThisPoly) Nz# = Nz# + Face_NZ#(ThisPoly) Next ; Normalize the new vertex normal. ; (Normalizing is scaling the vertex normal down so that it's length = 1) Nl# = Sqr(Nx#^2 + Ny#^2 + Nz#^2) ; Avoid a divide by zero error if by some freak accident, the vectors add up to 0. ; If Nl# = 0 Then Nl# = 0.1 Nx# = Nx# / Nl# Ny# = Ny# / Nl# Nz# = Nz# / Nl# ; Set the vertex normal. VertexNormal Surface_Handle, LOOP_Vertices, Nx#, Ny#, Nz# ;VertexColor Surface_Handle, LOOP_Vertices, polys*127, polys*127, polys*127 Next Next End Function |

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Swift... this code saved my terrain :D (build in normals in b3d has some buggs then using several alpha surface) |

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