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mcmonkey

(Solved)Render 3D Triangle List

7 posts in this topic


I want to render semi-dynamic 3D models... the built in Model class won't work.
So I thought I'd use a simple array of Vertices and render triangles from that...

I've looked all around the internet, and cannot figure out how to do it.

Here's what I'm currently trying:

        public static VertexPositionNormalTexture[] MapMesh = new VertexPositionNormalTexture[1];
        public static void GenMesh()
        {
            MapMesh = new VertexPositionNormalTexture[3];
            MapMesh[0].Position = new Vector3(-0.5f, -0.5f, 0f);
            MapMesh[1].Position = new Vector3(0, 0.5f, 0.1f);
            MapMesh[2].Position = new Vector3(0.5f, -0.5f, 0f);
        }
        public static void DrawMesh(GraphicsDevice device)
        {
            device.DrawUserPrimitives(PrimitiveType.TriangleList, MapMesh, 0, MapMesh.Length/3);
            Models.drawmodel(Models.cube, new Vector3(-1, -1, -5), Vector3.Zero, Textures.textures[Console.constext], Vector3.One);
        }

GenMesh is called once, DrawMesh is called in the Draw loop somewhere shortly after the code

// effect is a BasicEffect.
                effect.View = (camera.ViewMatrix);
                effect.Projection = (camera.ProjectionMatrix);
                effect.World = (Matrix.Identity);
                effect.TextureEnabled = true;
                effect.Texture = Textures.White;
                foreach (EffectPass pass in effect.CurrentTechnique.Passes)
                {
                    pass.Apply();
                }

the drawmodel(Models.cube bit is just so I can make sure I've pointed the camera at the right spot.

All I see is the cube, no triangle.

- Also, I have CullMode set to None.


What am I missing here?

 

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Change this

 

public static VertexPositionNormalTexture[] MapMesh = new VertexPositionNormalTexture[1];
public static void GenMesh()
{
    MapMesh = new VertexPositionNormalTexture[3];
    MapMesh[0].Position = new Vector3(-0.5f, -0.5f, 0f);
    MapMesh[1].Position = new Vector3(0, 0.5f, 0.1f);
    MapMesh[2].Position = new Vector3(0.5f, -0.5f, 0f);
}
public static void DrawMesh(GraphicsDevice device)
{
    device.DrawUserPrimitives(PrimitiveType.TriangleList, MapMesh, 0, MapMesh.Length/3);
    Models.drawmodel(Models.cube, new Vector3(-1, -1, -5), Vector3.Zero, Textures.textures[Console.constext], Vector3.One);
}

 

 

to this :

 

 

public static VertexPositionNormalTexture[] MapMesh = new VertexPositionNormalTexture[3];
public static void GenMesh()
{
    MapMesh[0].Position = new Vector3(-0.5f, -0.5f, 0f);
    MapMesh[1].Position = new Vector3(0, 0.5f, 0f);
    MapMesh[2].Position = new Vector3(0.5f, -0.5f, 0f);
}
public static void DrawMesh(GraphicsDevice device)
{
    Models.drawmodel(Models.cube, new Vector3(-1, -1, -5), Vector3.Zero, Textures.textures[Console.constext], Vector3.One);
    device.DrawUserPrimitives(PrimitiveType.TriangleList, MapMesh, 0, MapMesh.Length/3);
}

 

 

and then see if this helps.

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try switching vertices 1 and 2 to see if the triangle isn't facing the other way.

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try switching vertices 1 and 2 to see if the triangle isn't facing the other way.

Nope. I have culling off.

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Hard to say what you're doing wrong without seeing the complete code.

 

I created a new XNA project, and added a triangle into the draw method and it displays fine.

 

My draw method looks like this:

 

[code] 

 protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);
 
            var verts = new VertexPositionNormalTexture[3];
 
            verts[0].Position = new Vector3(-0.5f, -0.5f, 0.0f);
            verts[1].Position = new Vector3(0.0f, 0.5f, 0.0f);
            verts[2].Position = new Vector3(0.5f, -0.5f, 0.0f);
 
 
            var be = new BasicEffect(_graphics.GraphicsDevice);
 
            foreach (var pass in be.CurrentTechnique.Passes)
            {
                pass.Apply();
 
                _graphics.GraphicsDevice.DrawUserPrimitives(PrimitiveType.TriangleList, verts, 0, 1);
            }
 
            // TODO: Add your drawing code here);
 
            base.Draw(gameTime);
        }
[/code]
 
 
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... Aaaand now I'm embarassed.

There was nothing wrong with my code - just I was expecting a white triangle, and got a triangle that's pitch black, same as that area's background. DIscovered this when I tried using a larger triangle.

(Thanks for trying to help though.)

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