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# [XNA] Problems Creating Terrain

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Hi there, i am Trying to Create a 3D Tilemap, and im having some Problem with either working out the Verticies Positions, o the Index's. This map is flat along the X and Z Axis, Y = 0 all the time; First a few Variables
MapWidth = the Width of the Map (in tiles)
MapDepth = the depth of the map (in tiles)

TileWidth = the Width of a tile(in Pixels)
TileDepth = the Depth of a Tile(in Pixels)

this is how I create the Vertices:
ia_mapLayout = SetBlankArray(0); //sets it all to 0

for (int x = 0; x < MapWidth; x++)
{
for (int z = 0; z < MapDepth; z++)
{
Color staticColor = Color.White;

Vector3 bottomLeft  = new Vector3(x,  0,  z);                          // 0 [Bottom Left]
Vector3 bottomRight = new Vector3(x + 1,  0,  z);               // 1 [Bottom Right]
Vector3 topLeft     = new Vector3(x,  0,  z + 1);                  // 2 [Top Left]
Vector3 topRight    = new Vector3(x + 1,  0,  z + 1);              // 3 [Top Right]

l_Vertex.Add(new VertexPositionColor(topRight, staticColor));
l_Vertex.Add(new VertexPositionColor(bottomRight, staticColor));
l_Vertex.Add(new VertexPositionColor(bottomLeft, staticColor));

l_Vertex.Add(new VertexPositionColor(topRight, staticColor));
l_Vertex.Add(new VertexPositionColor(topLeft, staticColor));
l_Vertex.Add(new VertexPositionColor(bottomLeft, staticColor));
}
}


The Idea is, at each 0 in the array, create 2 new Triangles this is how I create the Indices:
ia_Indices = new int[(MapWidth - 1) * (MapDepth - 1) * 6];
int counter = 0;
for (int x = 0; x < MapWidth - 1; x++)
{
for (int z = 0; z < MapDepth - 1; z++)
{
int IndexZero = x;
int IndexOne = x + 1;
int IndexTwo = (x + 1) + MapWidth ;
int IndexThree = IndexTwo + 1;

ia_Indices[counter++] = IndexThree;
ia_Indices[counter++] = IndexOne;
ia_Indices[counter++] = IndexZero;

ia_Indices[counter++] = IndexThree;
ia_Indices[counter++] = IndexTwo;
ia_Indices[counter++] = IndexZero;
}
}


in this example, MapSize = 50x50, and tiles or 3.0fx3.0f Now, Once I have done that, I move these to the Index and Vertex Buffers, and the draw the Prims. Ok, so now all the Code is out of the way, here is the Problem: A Picture of them Problem (this is my personal Server hosted by BT) From what I can tell, its a problem with the Indices, and they all draw along the First X plane only (when x = 0 && x =1) .... and some link themselves back to x = 0 and z = 0; However, I find it encouraging that there are some Squares in there :) if anyone could perhaps show me where I am going wrong, in my head (and paper) the maths for the indices works out (I think) although my knowlage of them maynot be great. Thanks in Advanced .... Andy^ [Edited by - jpetrie on October 14, 2009 3:03:47 PM]

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The first problem I see is that you're creating 6 vertices for each square, you only need 4 when you have indices to build the triangles.

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Ok, so I now Only create the 4 Vertices

Vector3 bottomLeft  = new Vector3(x,  0,  z);                          // 0 [Bottom Left]                    Vector3 bottomRight = new Vector3(x + 1,  0,  z);               // 1 [Bottom Right]                    Vector3 topLeft     = new Vector3(x,  0,  z + 1);                  // 2 [Top Left]                    Vector3 topRight    = new Vector3(x + 1,  0,  z + 1);              // 3 [Top Right]                    l_Vertex.Add(new VertexPositionColor(bottomLeft, staticColor));                    l_Vertex.Add(new VertexPositionColor(bottomRight, staticColor));                    l_Vertex.Add(new VertexPositionColor(topLeft, staticColor));                    l_Vertex.Add(new VertexPositionColor(topRight, staticColor));

However the map when drawn is still getting almost the same result

However, I'm not sure if the Problem is within the Indicies, or in the Verticies.

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OK, I think i've Fixed this now.

I Simply got rid of Indices, and created the vertex, at(x,0,-z). This does mean I need 6 vertices for each sq, but I suppose it wont affect performance to much, if it does i can always attempt to add them in later

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