3D Primitive rendering problem

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manuelparente Posted: 06-14-2012 6:50 AM

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Hi I'm having a problem rendering a primitive generate through vertex and index buffers.

The problem is this:

Is this a common issue that i'm not seeing or is it more complex? Do you know how to solve it?

I'll put in some code if needed.

Thanks!

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JohnK "bobthecbuilder" replied on 06-14-2012 5:44 PM

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Hi manuel,

Is the object using a SunBurn material / effect?  If so please make sure to populate the mesh's tangent space information by calling:

VertexPositionNormalTextureBump.BuildTangentSpaceDataForTriangleList();

Let me know if this helps!

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manuelparente replied on 06-15-2012 6:20 AM

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Hi Bob,

thanks for your help but it didn't work.

The vertex buffer and index buffer are set using: 

        /// <summary>
        /// Once all the geometry has been specified by calling AddVertex and AddIndex,
        /// this method copies the vertex and index data into GPU format buffers, ready
        /// for efficient rendering.
        protected void InitializePrimitive(GraphicsDevice graphicsDevice)
        {
            // Create a vertex declaration, describing the format of our vertex data.
 
            // Create a vertex buffer, and copy our vertex data into it.
            vertexBuffer = new VertexBuffer(graphicsDevice,
                                            typeof(VertexPositionNormalTextureBump),
                                            vertices.Count, BufferUsage.WriteOnly);
 
            ushort[] indices_array = indices.ToArray();
 
            VertexPositionNormalTextureBump[] vertices_array = vertices.ToArray();
 
            VertexPositionNormalTextureBump.BuildTangentSpaceDataForTriangleList<ushort>(indices_array, vertices_array);
 
            vertexBuffer.SetData(vertices_array);
            
 
            // Create an index buffer, and copy our index data into it.
            indexBuffer = new IndexBuffer(graphicsDevice, typeof(ushort),
                                          indices.Count, BufferUsage.WriteOnly);
 
            indexBuffer.SetData(indices_array);

}

and the Primitive is being generated by:

public TorusPrimitive(GraphicsDevice graphicsDevice,
                              float diameter, float thickness, int tessellation)
        {
            if (tessellation < 3)
                throw new ArgumentOutOfRangeException("tessellation");
 
            // First we loop around the main ring of the torus.
            for (int i = 0; i < tessellation; i++)
            {
                float outerAngle = i * MathHelper.TwoPi / tessellation;
 
                // Create a transform matrix that will align geometry to
                // slice perpendicularly though the current ring position.
                Matrix transform = Matrix.CreateTranslation(diameter / 2, 0, 0) *
                                   Matrix.CreateRotationY(outerAngle);
 
                // Now we loop along the other axis, around the side of the tube.
                for (int j = 0; j < tessellation; j++)
                {
                    float innerAngle = j * MathHelper.TwoPi / tessellation;
 
                    float dx = (float)Math.Cos(innerAngle);
                    float dy = (float)Math.Sin(innerAngle);
 
                    // Create a vertex.
                    Vector3 normal = new Vector3(dx, dy, 0);
                    Vector3 position = normal * thickness / 2;
 
                    position = Vector3.Transform(position, transform);
                    normal = Vector3.TransformNormal(normal, transform);
 
                    AddVertex(position, normal);
 
                    // And create indices for two triangles.
                    int nextI = (i + 1) % tessellation;
                    int nextJ = (j + 1) % tessellation;
 
                    AddIndex(i * tessellation + j);
                    AddIndex(i * tessellation + nextJ);
                    AddIndex(nextI * tessellation + j);
 
                    AddIndex(i * tessellation + nextJ);
                    AddIndex(nextI * tessellation + nextJ);
                    AddIndex(nextI * tessellation + j);
                }
            }
            
 
            InitializePrimitive(graphicsDevice);
        }

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manuelparente replied on 06-15-2012 6:22 AM

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Also the Torus is being added to the scene by:

            TorusPrimitive torus = new TorusPrimitive(this.GraphicsDevice,100,20,50);
 
            SunBurnBasicEffect be = new SunBurnBasicEffect(this.GraphicsDevice) {
                 
                AmbientLightColor = new Vector3(1,0,0),
                TransparencyMode = SynapseGaming.LightingSystem.Core.TransparencyMode.Blend,
                Alpha =.5f,
                LightingEnabled=true,
                //PreferPerPixelLighting = true,
                DoubleSided=true,
                DiffuseColor = new Vector3(0,1,0),
                TextureEnabled = false
            };
 
            be.EnableDefaultLighting();
 
            SceneObject so = new SceneObject(
                "torusinho", true,
                be,
                new BoundingSphere(),
                new BoundingBox(),
                Matrix.Identity,
                torus.indexBuffer,
                torus.vertexBuffer,
                0,
                PrimitiveType.TriangleList,
                torus.indices.Count,
                0,
                torus.vertices.Count,
                0
 
                );

 
 
            sceneInterface.ObjectManager.Submit(so);