CODEWITHSUNDEEP
c#xna
Christian Frantz
Christian Frantz

Reputation: 253

Weird cube shape

I'm trying to create a cube with both indices and vertices. I'm able to draw them, but they look kinda weird.

enter image description here

Here's my code. It has something to do with either the vertices or indices, but I'm not sure which:

public void Draw(BasicEffect effect)
{
    foreach (EffectPass pass in effect.CurrentTechnique.Passes)
    {
        pass.Apply();
        device.SetVertexBuffer(cubeVertexBuffer);
        device.Indices = iBuffer;
        device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0,  8, 0, 12);
    }
}

private void SetUpIndices()
{
    indices = new short[36];

    indices[0] = 0;
    indices[1] = 3;
    indices[2] = 2;

    indices[3] = 2;
    indices[4] = 1;
    indices[5] = 0;

    indices[6] = 4;
    indices[7] = 7;
    indices[8] = 6;

    indices[9] = 6;
    indices[10] = 5;
    indices[11] = 4;

    indices[12] = 1;
    indices[13] = 2;
    indices[14] = 6;

    indices[15] = 6;
    indices[16] = 5;
    indices[17] = 1;

    indices[18] = 4;
    indices[19] = 7;
    indices[20] = 3;

    indices[21] = 3;
    indices[22] = 0;
    indices[23] = 4;

    indices[24] = 4;
    indices[25] = 0;
    indices[26] = 1;

    indices[27] = 1;
    indices[28] = 5;
    indices[29] = 4;

    indices[30] = 3;
    indices[31] = 7;
    indices[32] = 6;

    indices[33] = 6;
    indices[34] = 2;
    indices[35] = 3;

    iBuffer = new IndexBuffer(device, typeof(short), 36, BufferUsage.WriteOnly);
    iBuffer.SetData(indices);
}

private void SetUpVertices()
{
    vertices = new VertexPositionColor[8];


    vertices[0] = new VertexPositionColor(new Vector3(0, 0, 0), color);
    vertices[1] = new VertexPositionColor(new Vector3(0, 1, 0), color);
    vertices[2] = new VertexPositionColor(new Vector3(1, 1, 0), color);
    vertices[3] = new VertexPositionColor(new Vector3(1, 0, 0), color);
    vertices[4] = new VertexPositionColor(new Vector3(0, 0, -1), color);
    vertices[5] = new VertexPositionColor(new Vector3(0, 1, -1), color);
    vertices[6] = new VertexPositionColor(new Vector3(1, 1, -1), color);
    vertices[7] = new VertexPositionColor(new Vector3(1, 0, -1), color);

    cubeVertexBuffer = new VertexBuffer(device, typeof(VertexPositionColor), 8, BufferUsage.WriteOnly);
    cubeVertexBuffer.SetData<VertexPositionColor>(vertices);
}

Upvotes: 1

Views: 127

Answers (1)

athabaska
athabaska

Reputation: 455

I could do a wild guess and say its because of messed order of vertices in your indices (I would call them triangles further).

Usually in 3d engines you have to set up order of vertices in triangles so they all are ordered same - i.e. clockwise or counter-clockwise - when you look at them from outside of shape they form. Speaking mathematically all normals of triangles in your shape should be directed either inside or outside of shape. The direction of normal tells 3d engine when to draw triangles - engine can do two times less work if it draws triangles only on one side - the insides of a solid objects in 99,99% cases are not to be seen by user.

In your case look at indices 032 and 476 - they should be either 032/467 or 023/476. And so on.

Upvotes: 1

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