Renders a mesh within a libGDX widget.

ModelView

package com.traviswyatt.example.ui;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.GLCommon;
import com.badlogic.gdx.graphics.PerspectiveCamera;
import com.badlogic.gdx.graphics.Pixmap.Format;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.g3d.model.Model;
import com.badlogic.gdx.graphics.glutils.FrameBuffer;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;
import com.badlogic.gdx.math.Matrix4;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.math.Vector3;
import com.badlogic.gdx.math.collision.BoundingBox;
import com.badlogic.gdx.scenes.scene2d.ui.ClickListener;
import com.badlogic.gdx.scenes.scene2d.ui.Widget;

public class ModelView extends Widget {

	private PerspectiveCamera camera = new PerspectiveCamera(67, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
	
	private final Model model;
	private final ShaderProgram shader;
	
	private ClickListener clickListener;
	
	private final float prefWidth;
	private final float prefHeight;
	
	FrameBuffer frameBuffer = new FrameBuffer(Format.RGBA8888, Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), true);
	
	private static final Matrix4 modelView = new Matrix4();

	public ModelView(Model model, ShaderProgram shader, float width, float height, String name) {
		super(name);
		
		this.model = model;
		this.shader = shader;
		
		BoundingBox boundingBox = new BoundingBox();
		model.getBoundingBox(boundingBox);
		Vector3 center = boundingBox.getCenter();

		camera.position.set(boundingBox.max.x, boundingBox.max.y, boundingBox.max.z).mul(2);
		camera.lookAt(center.x, center.y, center.z);
		camera.up.set(0, 0, 1);
		camera.normalizeUp();
		camera.near = 1f;
		camera.far = new Vector3(camera.position).dst2(center) * 2f;
		camera.update();
		
		prefWidth = width;
		prefHeight = height;
	}
	
	@Override
	public float getPrefWidth() {
		return prefWidth;
	}
	
	@Override
	public float getPrefHeight() {
		return prefHeight;
	}
	
	@Override
	public void layout() {
		camera.update();
	}

	public void draw(SpriteBatch batch, float parentAlpha) {
		validate();
		batch.end();
		
		float dt = Gdx.graphics.getDeltaTime();
		modelView.rotate(0, 0, 1, 100 * dt);
		
		// actually stage coordinates!
		Vector2 tmp = Vector2.tmp.set(0, 0);
		toScreenCoordinates(this, tmp);
		
		GLCommon gl = Gdx.graphics.getGLCommon();
		gl.glViewport((int)tmp.x, (int)tmp.y, (int)width, (int)height);
		
		gl.glEnable(GL10.GL_DEPTH_TEST);
		gl.glDepthMask(true);
		gl.glDepthFunc(GL10.GL_LEQUAL);
		gl.glDepthRangef(0f, 1f);
		
		if (shader == null) {
			// FIXME glLight and rotate
			model.render();
		} else {
			Vector3 light = camera.position;
			shader.begin();
			shader.setUniformf("u_lightPosition", light.x, light.y, light.z);
			shader.setUniformMatrix("u_modelView", modelView);
			shader.setUniformMatrix("u_projModelView", camera.combined);
			model.render(shader);
			shader.end();
		}
		
		gl.glDisable(GL10.GL_DEPTH_TEST);
		gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
		
		batch.begin();
	}
	
	public boolean touchDown (float x, float y, int pointer) {
		return clickListener != null;
	}

	public void touchUp (float x, float y, int pointer) {
		if (hit(x, y) == null) return;
		if (clickListener != null) clickListener.click(this, x, y);
	}

	public void touchDragged (float x, float y, int pointer) {
	}

	public void setClickListener (ClickListener clickListener) {
		this.clickListener = clickListener;
	}
	
}