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10. January 2014

As I mentioned yesterday when talking about how to generate character sprites supporting dynamic inventory, the very first step would be to actually figure out how to do 3D in LibGDX.

 

Well, I did, and thankfully it’s pretty simple.  This isn’t a tutorial by any stretch of the means, but what follows is basically the “minimum” 3D application you can create in LibGDX.  It simple creates a blue cube and rotates the camera around it.  While it isn’t a tutorial, it is heavily documented, so you should be able to figure things out with ease, especially if you’ve already done my LibGDX tutorial series.

 

package com.gamefromscratch;

 

import com.badlogic.gdx.ApplicationListener;

import com.badlogic.gdx.Gdx;

import com.badlogic.gdx.graphics.Color;

import com.badlogic.gdx.graphics.GL10;

import com.badlogic.gdx.graphics.PerspectiveCamera;

import com.badlogic.gdx.graphics.VertexAttributes.Usage;

import com.badlogic.gdx.graphics.g3d.Environment;

import com.badlogic.gdx.graphics.g3d.Material;

import com.badlogic.gdx.graphics.g3d.Model;

import com.badlogic.gdx.graphics.g3d.ModelBatch;

import com.badlogic.gdx.graphics.g3d.ModelInstance;

import com.badlogic.gdx.graphics.g3d.attributes.ColorAttribute;

import com.badlogic.gdx.graphics.g3d.utils.ModelBuilder;

import com.badlogic.gdx.math.Vector3;

 

public class TestApp implements ApplicationListener {

   private PerspectiveCamera camera;

   private ModelBatch modelBatch;

   private Model box;

   private ModelInstance boxInstance;

   private Environment environment;

 

   @Override

   public void create() {

   // Create camera sized to screens width/height with Field of View of 75 degrees

      camera = new PerspectiveCamera(

      75,

      Gdx.graphics.getWidth(),

      Gdx.graphics.getHeight());

 

      // Move the camera 3 units back along the z-axis and look at the origin

      camera.position.set(0f,0f,3f);

      camera.lookAt(0f,0f,0f);

 

      // Near and Far (plane) repesent the minimum and maximum ranges of the camera in, um, units

      camera.near = 0.1f; 

      camera.far = 300.0f;

 

      // A ModelBatch is like a SpriteBatch, just for models.  Use it to batch up geometry for OpenGL

      modelBatch = new ModelBatch();

 

      // A ModelBuilder can be used to build meshes by hand

      ModelBuilder modelBuilder = new ModelBuilder();

 

      // It also has the handy ability to make certain premade shapes, like a Cube

      // We pass in a ColorAttribute, making our cubes diffuse ( aka, color ) red.

      // And let openGL know we are interested in the Position and Normal channels

      box = modelBuilder.createBox(2f, 2f, 2f, 

      new Material(ColorAttribute.createDiffuse(Color.BLUE)),

      Usage.Position | Usage.Normal

      );

 

      // A model holds all of the information about an, um, model, such as vertex data and texture info

      // However, you need an instance to actually render it.  The instance contains all the 

      // positioning information ( and more ).  Remember Model==heavy ModelInstance==Light

      boxInstance = new ModelInstance(box,0,0,0);

 

      // Finally we want some light, or we wont see our color.  The environment gets passed in during

      // the rendering process.  Create one, then create an Ambient ( non-positioned, non-directional ) light.

      environment = new Environment();

      environment.set(new ColorAttribute(ColorAttribute.AmbientLight, 0.8f, 0.8f, 0.8f, 1.0f));

   }

 

   @Override

   public void dispose() {

      modelBatch.dispose();

      box.dispose();

   }

 

   @Override

   public void render() {

      // You've seen all this before, just be sure to clear the GL_DEPTH_BUFFER_BIT when working in 3D

      Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());

      Gdx.gl.glClearColor(1, 1, 1, 1);

      Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

 

      // For some flavor, lets spin our camera around the Y axis by 1 degree each time render is called

      camera.rotateAround(Vector3.Zero, new Vector3(0,1,0),1f);

      // When you change the camera details, you need to call update();

      // Also note, you need to call update() at least once.

      camera.update();

 

      // Like spriteBatch, just with models!  pass in the box Instance and the environment

      modelBatch.begin(camera);

      modelBatch.render(boxInstance, environment);

      modelBatch.end();

   }

 

   @Override

   public void resize(int width, int height) {

   }

 

   @Override

   public void pause() {

   }

 

   @Override

   public void resume() {

   }

}

 

And when you run it you should see:

RotatingCube

 

Next up, loading a 3D model from Blender and playing the animations.

 

By the way, although this isn’t a tutorial, if you have a question about something I did feel free to use the comments and I will do my best to answer!

Programming , ,

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