MonoGame SharpDX Error 'The Parameter is Incorrect' when using graphics.DrawUserPrimitives [closed]

Question

Below is a small section of code that is meant to draw a multicolored triangle to the middle of the screen in a MonoGame game. This uses the basic function DrawUserPrimitives to draw the triangle. This works fine in XNA, but the moment i try to use it in a MonoGame DX game (Which compiles using SharpDX) it will crash with the following error:

An unhandled exception of type 'SharpDX.SharpDXException' occurred in SharpDX.dll

Additional information: HRESULT: [0x80070057], Module: [General], ApiCode: [E_INVALIDARG/Invalid Arguments], Message: The parameter is incorrect.

Below is the code that is causing the error.

private void SetUpVertices() {
        vertices = new VertexPositionColor[3];

        vertices[0].Position = new Vector3(-0.5f, -0.5f, 0f);
        vertices[0].Color = Color.Red;
        vertices[1].Position = new Vector3(0, 0.5f, 0f);
        vertices[1].Color = Color.Green;
        vertices[2].Position = new Vector3(0.5f, -0.5f, 0f);
        vertices[2].Color = Color.Yellow;
    }

    public void Draw(GameTime gameTime) {
        gDevice.DrawUserPrimitives(PrimitiveType.TriangleList, vertices, 0, 1, VertexPositionColor.VertexDeclaration);
    }

Has anyone ever come across simillar errors using the DirectX version on MonoGame and SharpDX when dealing with primatives? And do you know of a way I can fix this issue?

Answer 1

I had this all the time when building my engine core code it means you passed something to directx that isn't correct.

At a glance it appears you are passing a vertex array to a draw call .. this doesn't seem right to me although I haven't used monogame in some time (my code is sitting on the raw SharpDX API) so they may have done some wizardry to allow this but my get feel is that you need to put your vertices in to a buffer first then call draw on the buffer.

That said ... This question seems to imply that its fine and that actually you are missing your effect ...

Drawing simple geometric figures with DrawUserPrimitives?