DebugDrawer improved.

[nooone]

I have added a few more implementations to the DebugDrawer:

• reportErrorWarning
• drawContactPoint
• drawTriangle
• draw3dText

The draw3dText implementation is probably the most interesting part as it's in need of the current glViewport parameters, which is why I added begin(Viewport). Another alternative (@xoppa's idea) would be to keep track of the current glViewport paramters in a static way, for example via Gdx.graphics.getGlViewport(). A more slow (but maybe for debugging purposes appropriate?) way would be to just read it like this:

private static final Rectangle viewportRect = new Rectangle();

public static Rectangle getGlViewport() {
    FloatBuffer buffer = BufferUtils.newFloatBuffer(16);

    Gdx.graphics.getGL20().glGetFloatv(GL20.GL_VIEWPORT, buffer);
    viewportRect.x = buffer.get(0);
    viewportRect.y = buffer.get(1);
    viewportRect.width = buffer.get(2);
    viewportRect.height = buffer.get(3);

    return viewportRect;
}

In both cases we could get rid of the Viewport completely here.

The way this PR draws 3D text is by projecting the destination position to the screen and then drawing it in 2D, centered on the position. This has the advantage of pixel perfection. However there are also some drawbacks:

• Impossible to make use of the depth buffer
• The text has always the same size, however far away it is

I've tried to implement it following kalle_h's advice and draw it via the spritebatch with manipulated matrices to "real" 3D, however I could not make it work completely. Something must be wrong with the object matrix's rotation:

public void draw3dText(Vector3 location, String textString) {
    shapeRenderer.end();

    Matrix4 lookAtMatrix = new Matrix4().setToLookAt(location, camera.position, Vector3.Y);
    Quaternion lookAtQuaternion = new Quaternion();
    lookAtMatrix.getRotation(lookAtQuaternion, true);

    Matrix4 objectMatrix = new Matrix4();
    objectMatrix.set(location, lookAtQuaternion);

    spriteBatch.setProjectionMatrix(camera.combined);
    spriteBatch.setTransformMatrix(objectMatrix);
    spriteBatch.begin();

    Gdx.graphics.getGL20().glEnable(GL20.GL_DEPTH_TEST);

    TextBounds bounds = font.getBounds(textString);
    font.draw(spriteBatch, textString, -bounds.width / 2, bounds.height / 2);

    spriteBatch.end();
    shapeRenderer.begin(ShapeType.Line);
}

If we could get this to work, there's no need for the glViewport parameters at all.

[xoppa]

Note that the ShapeRenderer, BitmapFont and SpriteBatch have to be disposed when no longer needed. Could you make them private with setters and getters, along with a private boolean ownsFont etc? Then when the user provides one of those in the constructor or via the setter you set the ownsXXX boolean to false, otherwise to true. In the dispose method, when the ownsXXX field is true you dispose the corresponding member.

[nooone]

Good spot @xoppa! I've implemented it the way you described it.

[xoppa]

It looks like this is never used.

[xoppa]

this is the same as normalOnB.scl(distance).add(pointOnB);

[xoppa]

I'm not sure about creating a font and spritebatch (and thus Mesh and ShaderProgram) by default. As we've seen the draw3dText method is by default only called for softbody simulation. So in most cases the font and spritebatch aren't even used. Perhaps lazy initialization would be a better approach.

[nooone]

@xoppa: It seems like the libgdx projects are configured to not display warnings about unused fields? That's why I didn't notice it. I removed them and added the lazy initialization.

[xoppa]

I guess this would cause a NPE now :)

[nooone]

Haha, yeah I forgot that. Then tested it in my game and fixed it... but forgot to also apply the fix in my libgdx fork before commiting -.-

[xoppa]

Thanks!