如何找到使用顶点缓冲区制作的立方体的旋转中心？立方体目前正在一个顶点上旋转，我整周都在试图弄清楚如何将它调整到中心。
这是我渲染立方体的代码：
class RenderCube
{
KeyboardState currentKeys;
GamePadState currentGamepad;
//Transform later to have static v and i buffers.
private VertexBuffer vBuffer;
public VertexBuffer VBuffer
{ get { return vBuffer; } set { vBuffer = value; } }
private IndexBuffer iBuffer;
public IndexBuffer IBuffer
{ get { return iBuffer; } set { iBuffer = value; } }
private BasicEffect bEffect;
public BasicEffect BEffect
{ get { return bEffect; } set { bEffect = value; } }
private Matrix world;
public Matrix World
{ get { return world; } set { world = value; } }
private Matrix view;
public Matrix View
{ get { return view; } set { view = value; } }
private Matrix projection;
private Matrix Projection
{ get { return projection; } set { projection = value; } }
private Color color;
public Color Color
{ get { return color; } set { color = value; } }
private Vector3 position;
public Vector3 Position
{ get { return position; } set { position = value; } }
//Need to change this eventually to use textures.
private VertexPositionColor[] vertices;
short[] indices;
private GraphicsDevice device;
//constructors!
public RenderCube(Color col, Vector3 pos, GraphicsDevice dev)
{
device = dev;
this.color = col;
this.position = pos;
SetUpVertices();
SetUpIndices();
world = Matrix.CreateTranslation(position);
//world = Matrix.CreateTranslation(0, 0, 0);
bEffect = new BasicEffect(device);
bEffect.World = world;
bEffect.VertexColorEnabled = true;
//bEffect.EnableDefaultLighting();
}
public void Render(Camera cam)
{
bEffect.View = cam.view;
bEffect.Projection = cam.projection;
bEffect.World *= cam.rotX;
bEffect.World *= cam.rotY;
bEffect.World *= cam.rotZ;
var rotationCenter = new Vector3(0.5f, 0.5f, 0.5f);
device.SetVertexBuffer(vBuffer);
device.Indices = IBuffer;
foreach (EffectPass pass in bEffect.CurrentTechnique.Passes)
{
pass.Apply();
device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, 8, 0, 12);
}
}
/// <summary>
/// Sets up the vertices for a cube using 8 unique vertices.
/// Build order is front to back, left to up to right to down.
/// </summary>
private void SetUpVertices()
{
vertices = new VertexPositionColor[8];
//front left bottom corner
vertices[0] = new VertexPositionColor(new Vector3(0, 0, 0), color);
//front left upper corner
vertices[1] = new VertexPositionColor(new Vector3(0, 100, 0), color);
//front right upper corner
vertices[2] = new VertexPositionColor(new Vector3(100, 100, 0), color);
//front lower right corner
vertices[3] = new VertexPositionColor(new Vector3(100, 0, 0), color);
//back left lower corner
vertices[4] = new VertexPositionColor(new Vector3(0, 0, -100), color);
//back left upper corner
vertices[5] = new VertexPositionColor(new Vector3(0, 100, -100), color);
//back right upper corner
vertices[6] = new VertexPositionColor(new Vector3(100, 100, -100), color);
//back right lower corner
vertices[7] = new VertexPositionColor(new Vector3(100, 0, -100), color);
vBuffer = new VertexBuffer(device, typeof(VertexPositionColor), 8, BufferUsage.WriteOnly);
vBuffer.SetData<VertexPositionColor>(vertices);
}
/// <summary>
/// Sets up the indices for a cube. Has 36 positions that match up
/// to the element numbers of the vertices created earlier.
/// Valid range is 0-7 for each value.
/// </summary>
private void SetUpIndices()
{
indices = new short[36];
//Front face
//bottom right triangle
indices[0] = 0;
indices[1] = 3;
indices[2] = 2;
//top left triangle
indices[3] = 2;
indices[4] = 1;
indices[5] = 0;
//back face
//bottom right triangle
indices[6] = 4;
indices[7] = 7;
indices[8] = 6;
//top left triangle
indices[9] = 6;
indices[10] = 5;
indices[11] = 4;
//Top face
//bottom right triangle
indices[12] = 1;
indices[13] = 2;
indices[14] = 6;
//top left triangle
indices[15] = 6;
indices[16] = 5;
indices[17] = 1;
//bottom face
//bottom right triangle
indices[18] = 4;
indices[19] = 7;
indices[20] = 3;
//top left triangle
indices[21] = 3;
indices[22] = 0;
indices[23] = 4;
//left face
//bottom right triangle
indices[24] = 4;
indices[25] = 0;
indices[26] = 1;
//top left triangle
indices[27] = 1;
indices[28] = 5;
indices[29] = 4;
//right face
//bottom right triangle
indices[30] = 3;
indices[31] = 7;
indices[32] = 6;
//top left triangle
indices[33] = 6;
indices[34] = 2;
indices[35] = 3;
iBuffer = new IndexBuffer(device, IndexElementSize.SixteenBits, sizeof(short) * indices.Length, BufferUsage.WriteOnly);
iBuffer.SetData(indices);
}
}