Drawing a 2D HUD messes up rendering of my 3D models?

Question

I\'m using XNA 3.1

I have recently created a 2D Heads Up Display (HUD) by using Components.Add(myComponent) to my game. The HUD looks fine, showing a 2D map

Answer 1

You have to enable the depth buffer:

// XNA 3.1
GraphicsDevice.RenderState.DepthBufferEnable = true;
GraphicsDevice.RenderState.DepthBufferWriteEnable = true;

// XNA 4.0
GraphicsDevice.DepthStencilState = DepthStencilState.Default;

SpriteBatch.Begin alters the state of the graphics pipeline:

• SpriteBatch render states for XNA 3.1
• SpriteBatch render states for XNA 4.0

In both versions depth buffering is disabled, that's what causes the issue.

Again, I cannot stress this enough:

Always make sure that ALL render states are correctly set before drawing any geometry.

• BlendState
• DepthStencilState
• RasterizerState
• Viewports
• RenderTargets
• Shaders
• SamplerStates
• Textures
• Constants

Educate yourself on the purpose of each state and each stage in the rendering pipeline. If in doubt, try resetting everything to default.