3D objects are drawn over each other. My depth buffering isn't working

Graphics
1

Hey, I’m having trouble with overlapping 3d objects. My 3D rendered models/objects are drawn on top based on which draw method gets called last instead of basing it off the pixel’s position relative to the camera.

I asked in the Discord and I was told that either my “depth read” or “depth write” are failing. My “Depth read” is I assume setting the DepthStencilState to default:

            graphicsDevice.DepthStencilState = DepthStencilState.Default;

And the depth write is this right:

GraphicsDevice.Clear(Color.CornflowerBlue);
 GraphicsDevice.Clear(ClearOptions.DepthBuffer, Color.Black, 1.0f, 0);

I’ve tried everything. My only theory left is that I keep resetting the graphicsDevice Vertexbuffer by this line of code

                graphicsDevice.SetVertexBuffer(shape.vertexBuffer);

But ChatGPT informed me that isn’t a problem. Does anyone have an idea where my problem lies?

Here is how I draw my 3D objects

	public override void Draw(GameTime gameTime, SpriteBatch spriteBatch) {
            graphicsDevice.DepthStencilState = DepthStencilState.Default;
            graphicsDevice.BlendState = BlendState.Opaque; // Spritebatch sets it default to AlphaBlend

            base.Draw(gameTime, spriteBatch);
            Draw3DModels();
            Draw3DShapes();
        }

        private void Draw3DModels() {
            foreach (ThreeDGameObject threeDGameObject in ThreeDObjects) {
                Model model = threeDGameObject.model;
                foreach (ModelMesh mesh in model.Meshes) {
                    foreach (BasicEffect effect in mesh.Effects) {

                        // Transformations
                        Matrix worldMatrix = Matrix.CreateTranslation(threeDGameObject.Position) *
                            Matrix.CreateFromYawPitchRoll(threeDGameObject.Rotation.Y, threeDGameObject.Rotation.X, threeDGameObject.Rotation.Z);
                        effect.World = worldMatrix;
                        effect.View = camera.View;
                        effect.Projection = camera.Projection;

                        // Light
                        // effect.AmbientLightColor = new Vector3(1f, 0, 0);
                        // effect.EnableDefaultLighting();

                        // Other shader settings
                        effect.TextureEnabled = true;
                        effect.Alpha = threeDGameObject.Alpha;

                        effect.CurrentTechnique.Passes[0].Apply();
                    }

                    mesh.Draw();
                }
            }
        }

        private void Draw3DShapes() {
            basicEffect.Projection = camera.Projection;
            basicEffect.View = camera.View;
            basicEffect.World = camera.World;

            // Draw all shapes
            foreach (Shape shape in shapes) { 
                // Transformations
                Matrix worldMatrix = Matrix.CreateTranslation(shape.Position) *
                    Matrix.CreateFromYawPitchRoll(shape.Rotation.Y, shape.Rotation.X, shape.Rotation.Z);
                basicEffect.World = worldMatrix;

                graphicsDevice.SetVertexBuffer(shape.vertexBuffer);
                graphicsDevice.Indices = shape.indexBuffer;

                foreach (EffectPass pass in basicEffect.CurrentTechnique.Passes) { 
                    pass.Apply();
                    graphicsDevice.DrawPrimitives(PrimitiveType.TriangleList, 0, shape.vertices.Length / 3);
                }
            }
        }

Could the problem be in the camera?

I am in Visual Studio Code
Monogame version: 3.8.1.303

2

I believe this is what you’re looking for: 2D and 3D Combined - RB Whitaker's Wiki

3

For some reason setting a new viewport outside of the initializer of the Game class will disable the depth buffer’s functionality of your graphicsdephice, even if you set the DepthStencilState back to default every frame.

        Viewport viewport = new Viewport();
        viewport.X = (graphics.PreferredBackBufferWidth / 2) - (screenWidth / 2);
        viewport.Y = (graphics.PreferredBackBufferHeight / 2) - (screenHeight / 2);
        viewport.Width = screenWidth;
        viewport.Height = screenHeight;
        GraphicsDevice.Viewport = viewport;

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