Rendering Debug Information

This topic describes the DebugRenderer, which can be used to draw debug information.

This topic contains the following sections:

DebugRenderer
Examples

DebugRenderer

The DebugRenderer is a tool for rendering debug information. It can be used to print text, visualize shapes, textures, and more.

Important
The DebugRenderer is intended purely for rendering debug information. It is not designed for rendering regular content.

The debug renderer records and batches a list of draw jobs. A draw job is added by calling one of the Draw methods. Note that the Draw methods can be called outside of the Game.Draw() method! For example, debug output can be added during Game.Update() when the game logic is executed.

Important
The DebugRenderer is not thread-safe. To add draw jobs from multiple threads simultaneously either use locks or use multiple DebugRenderers (one per thread).

The method Render can be called at any time during Game.Draw() to output all recorded draw jobs.

The method Clear can be called to clear the list of draw jobs. (Rendering the list of draw jobs does not automatically clear the list!)

Tip
If your application needs to output two types of debug information - for example, one that is updated per every frame and one that persistent across frames - you can simply use two instances of the DebugRenderer class.

Examples

The following examples show how create a new DebugRenderer (usually at the start of the application).

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// Use a content manager to load sprite font for debug text.
var debugFont = GraphicsService.Content.Load<SpriteFont>("DebugFont");

// Create a new debug renderer.
var debugRenderer = new DebugRenderer(graphicsService, debugFont) 
{ 
  DefaultColor = Color.White 
};

Once the debug renderer is created it can be used to record debug output.

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// Clear list of draw jobs.
debugRenderer.Clear();

// Draw a point.
debugRenderer.DrawPoint(position, Color.White, false);

// Draw a line.
debugRenderer.DrawLine(start, end, Color.Red, false);

// Draw continuous text.
debugRenderer.DefaultTextPosition = new Vector2F(10, 10);
debugRenderer.DrawText("Line #1...");
debugRenderer.DrawText("Line #2..");
debugRenderer.DrawText("Line #3...");

// Draw centered text at world space position.
debugRenderer.DrawText("WorldSpacePosition (0, 0)", new Vector3F(0, 0, 0), new Vector2F(0.5f, 0.5f), Color.White, false);

// Draw left/top aligned text at screen space position.
debugRenderer.DrawText("ScreenPosition (600, 40)", new Vector2F(600, 40), new Vector2F(0, 0), Color.White);

// Copy texture to screen for debugging.
debugRenderer.DrawTexture(texture2D, new Rectangle(1000, 10, 128, 128));

// Draw coordinate axes for certain pose (position + orientation).
debugRenderer.DrawAxes(new Pose(new Vector3F(0, 0, 0)), 1, true);

// Draw axis-aligned bounding box (AABB).
debugRenderer.DrawAabb(new Aabb(new Vector3F(-0.5f), new Vector3F(0.5f)), new Pose(new Vector3F(2, 0, -3)), Color.Green, false);

// Draw different shapes.
debugRenderer.DrawBox(1, 1, 1, new Pose(new Vector3F(-6, 0, -5)), Color.Green, false, false);
debugRenderer.DrawViewVolume(new PerspectiveViewVolume(1, 2, 0.1f, 1f), new Pose(new Vector3F(-2, 0, -5)), Color.Green, false, false);
debugRenderer.DrawSphere(0.5f, new Pose(new Vector3F(2, 0, -5)), Color.Green, false, false);
debugRenderer.DrawCapsule(0.3f, 1, new Pose(new Vector3F(-6, 0, -7)), Color.Green, false, false);
debugRenderer.DrawCylinder(0.3f, 1, new Pose(new Vector3F(-2, 0, -7)), Color.Green, false, false);
debugRenderer.DrawCone(0.3f, 1, new Pose(new Vector3F(2, 0, -7)), Color.Green, false, false);

// Draw any IGeometricObject (GeometricObject, RigidBody, SceneNode, ParticleSystem, etc.).
debugRenderer.DrawObject(geometricObject, Color.Brown, false, false);

// Draw an XNA Model or DigitalRune ModelNode.
debugRenderer.DrawModel(xnaModel, new Pose(new Vector3F(0, 2, -2)), new Vector3F(1, 1, 1), Color.Brown, false, false);
debugRenderer.DrawModel(modelNode, Color.Brown, false, false);

The recorded draw jobs can then be rendered.

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// Make sure that the current camera is set in the render context.
context.CameraNode = cameraNode;

// Render draw jobs. (Can only be called during Game.Draw()).
debugRenderer.Render(context);