So I am following this tutorial on how to draw a cube in XNA and I ran into a problem. Ok so my shader can only have texture right? I need to have a texture on the front and back of my cube. So I thought I could just have both textures stored in one texture. Problem is I do not know how to map out my UV coords to do so. (I tried dividing by 2 and such with no luck...). I am really new to this (not programming, just game development and some concepts), but how could I get UV coordinates for both halfs of the texture.
private void ConstructCube(Vector3 Position,Vector3 Size)
{
_vertices = new VertexPositionNormalTexture[50];
// Calculate the position of the vertices on the top face.
Vector3 topLeftFront = Position + new Vector3(-1.0f, 1.0f, -1.0f) * Size;
Vector3 topLeftBack = Position + new Vector3(-1.0f, 1.0f, 1.0f) * Size;
Vector3 topRightFront = Position + new Vector3(1.0f, 1.0f, -1.0f) * Size;
Vector3 topRightBack = Position + new Vector3(1.0f, 1.0f, 1.0f) * Size;
// Calculate the position of the vertices on the bottom face.
Vector3 btmLeftFront = Position + new Vector3(-1.0f, -1.0f, -1.0f) * Size;
Vector3 btmLeftBack = Position + new Vector3(-1.0f, -1.0f, 1.0f) * Size;
Vector3 btmRightFront = Position + new Vector3(1.0f, -1.0f, -1.0f) * Size;
Vector3 btmRightBack = Position + new Vector3(1.0f, -1.0f, 1.0f) * Size;
// Normal vectors for each face (needed for lighting / display)
Vector3 normalFront = new Vector3(0.0f, 0.0f, 1.0f) * Size;
Vector3 normalBack = new Vector3(0.0f, 0.0f, -1.0f) * Size;
Vector3 normalTop = new Vector3(0.0f, 1.0f, 0.0f) * Size;
Vector3 normalBottom = new Vector3(0.0f, -1.0f, 0.0f) * Size;
Vector3 normalLeft = new Vector3(-1.0f, 0.0f, 0.0f) * Size;
Vector3 normalRight = new Vector3(1.0f, 0.0f, 0.0f) * Size;
// UV texture coordinates
Vector2 textureTopLeft = new Vector2(1.0f * Size.X, 0.0f * Size.Y);
Vector2 textureTopRight = new Vector2(0.0f * Size.X, 0.0f * Size.Y);
Vector2 textureBottomLeft = new Vector2(1.0f * Size.X, 1.0f * Size.Y);
Vector2 textureBottomRight = new Vector2(0.0f * Size.X, 1.0f * Size.Y);
// Add the vertices for the FRONT face.
_vertices[0] = new VertexPositionNormalTexture(topLeftFront, normalFront, textureTopLeft);
_vertices[1] = new VertexPositionNormalTexture(btmLeftFront, normalFront, textureBottomLeft);
_vertices[2] = new VertexPositionNormalTexture(topRightFront, normalFront, textureTopRight);
_vertices[3] = new VertexPositionNormalTexture(btmLeftFront, normalFront, textureBottomLeft);
_vertices[4] = new VertexPositionNormalTexture(btmRightFront, normalFront, textureBottomRight);
_vertices[5] = new VertexPositionNormalTexture(topRightFront, normalFront, textureTopRight);
// Add the vertices for the BACK face.
_vertices[6] = new VertexPositionNormalTexture(topLeftBack, normalBack, textureTopRight);
_vertices[7] = new VertexPositionNormalTexture(topRightBack, normalBack, textureTopLeft);
_vertices[8] = new VertexPositionNormalTexture(btmLeftBack, normalBack, textureBottomRight);
_vertices[9] = new VertexPositionNormalTexture(btmLeftBack, normalBack, textureBottomRight);
_vertices[10] = new VertexPositionNormalTexture(topRightBack, normalBack, textureTopLeft);
_vertices[11] = new VertexPositionNormalTexture(btmRightBack, normalBack, textureBottomLeft);
// Add the vertices for the TOP face.
_vertices[12] = new VertexPositionNormalTexture(topLeftFront, normalTop, textureBottomLeft);
_vertices[13] = new VertexPositionNormalTexture(topRightBack, normalTop, textureTopRight);
_vertices[14] = new VertexPositionNormalTexture(topLeftBack, normalTop, textureTopLeft);
_vertices[15] = new VertexPositionNormalTexture(topLeftFront, normalTop, textureBottomLeft);
_vertices[16] = new VertexPositionNormalTexture(topRightFront, normalTop, textureBottomRight);
_vertices[17] = new VertexPositionNormalTexture(topRightBack, normalTop, textureTopRight);
// Add the vertices for the BOTTOM face.
_vertices[18] = new VertexPositionNormalTexture(btmLeftFront, normalBottom, textureTopLeft);
_vertices[19] = new VertexPositionNormalTexture(btmLeftBack, normalBottom, textureBottomLeft);
_vertices[20] = new VertexPositionNormalTexture(btmRightBack, normalBottom, textureBottomRight);
_vertices[21] = new VertexPositionNormalTexture(btmLeftFront, normalBottom, textureTopLeft);
_vertices[22] = new VertexPositionNormalTexture(btmRightBack, normalBottom, textureBottomRight);
_vertices[23] = new VertexPositionNormalTexture(btmRightFront, normalBottom, textureTopRight);
// Add the vertices for the LEFT face.
_vertices[24] = new VertexPositionNormalTexture(topLeftFront, normalLeft, textureTopRight);
_vertices[25] = new VertexPositionNormalTexture(btmLeftBack, normalLeft, textureBottomLeft );
_vertices[26] = new VertexPositionNormalTexture(btmLeftFront, normalLeft, textureBottomRight );
_vertices[27] = new VertexPositionNormalTexture(topLeftBack, normalLeft, textureTopLeft);
_vertices[28] = new VertexPositionNormalTexture(btmLeftBack, normalLeft, textureBottomLeft );
_vertices[29] = new VertexPositionNormalTexture(topLeftFront, normalLeft, textureTopRight );
// Add the vertices for the RIGHT face.
_vertices[30] = new VertexPositionNormalTexture(topRightFront, normalRight, textureTopLeft);
_vertices[31] = new VertexPositionNormalTexture(btmRightFront, normalRight, textureBottomLeft);
_vertices[32] = new VertexPositionNormalTexture(btmRightBack, normalRight, textureBottomRight);
_vertices[33] = new VertexPositionNormalTexture(topRightBack, normalRight, textureTopRight);
_vertices[34] = new VertexPositionNormalTexture(topRightFront, normalRight, textureTopLeft);
_vertices[35] = new VertexPositionNormalTexture(btmRightBack, normalRight, textureBottomRight);
done = true;
}
