Chapter 16

Introduction to 3D Graphics and Games

This chapter examines how to develop 3D games.

As suggested by the book the following features have been added:

• Rectangle Destroyer 3D

3 Dimensional Considerations

As it turns out, all previous games are created in a 3D space. This may be hard to realise because of the z-axis is pointing toward the camera/player, perpendicular to the xy plane (i.e a bird's view).

• Orthogonal Projection: If the edges of an object have the same length, then they will be drawn as having the same length in the projection, regardless of their distance from the viewer.
• Perspective Projection: An edge farther away from the viewer will appear shorter.

If two edges of an object are parallel, then they remain parallel in an orthographic projection, but they appear to converge in a perspective projection.

A PerspectiveCamera requires a visible region defined.

camera = PerspectiveCamera(67f, Gdx.graphics.width.toFloat(), Gdx.graphics.height.toFloat())
camera.near = .1f
camera.far = 1000f
camera.position.set(10f, 10f, 10f)
camera.lookAt(0f, 0f, 0f)
camera.update()

Instead of a SpriteBatch renders 2-dimensional objects, a ModelBatch is used to render 3-dimensional objects. Data needed to draw an object is contained in a ModelObject, which consists of a Mesh and a Material. The mesh is a collection of vertices, edges, and triangular faces, and together define the shape of an object. A material contains the color or texture data applied to the mesh.

Lights provide a way to view 3-dimensional objects. The two kinds used in this project are AmbientLight and DirectionalLight.

Creating a Minimal 3D Demo

A minimal demo of the LibGDX's 3D capabilities is found in the package demoCube. Coincidentally Xoppa's tutorial explains the same steps as the book does.

Creating an Interactive 3D Demo

Further, the book explains how to make a more interactive demo. View the README.md for the controls.

Starfish Collector 3D

The project describes how to implement the Starfish Collector 3D game.

Rectangle Destroyer 3D

As suggested by the book the Rectangle Destroyer 3D game was created. Although minimalistic, it proves the point and is surprisingly impressive.

Other Tutorials

• Basic 3D using libGDX -by Xoppa

New Imports

import com.badlogic.gdx.graphics.PerspectiveCamera - A Camera with perspective projection.

import com.badlogic.gdx.graphics.VertexAttributes.Usage - The usage of a vertex attribute.

import com.badlogic.gdx.graphics.g3d.Environment - The 3D environment which contains everything

import com.badlogic.gdx.graphics.g3d.attributes.ColorAttribute - Color attributes

import com.badlogic.gdx.graphics.g3d.environment.DirectionalLight - A light that gets emitted in a specific direction.

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

import com.badlogic.gdx.graphics.g3d.Model - Helper class to create Models from code.

import com.badlogic.gdx.graphics.g3d.ModelBatch - Batches Renderable instances, fetches Shaders for them, sorts them and then renders them.

import com.badlogic.gdx.graphics.g3d.ModelInstance - An instance of a Model, allows to specify global transform and modify the materials, as it has a copy of the model's materials.

import com.badlogic.gdx.graphics.g3d.Material - A renderable material

import com.badlogic.gdx.graphics.g3d.loader.ObjLoader - ModelLoader to load Wavefront OBJ files.

import com.badlogic.gdx.math.Vector3 - Encapsulates a 3D vector. Allows chaining operations by returning a reference to itself in all modification methods.

import com.badlogic.gdx.math.Quaternion - A simple quaternion class.

import com.badlogic.gdx.math.Matrix4 - Encapsulates a column major 4 by 4 matrix. Like the Vector3 class it allows the chaining of methods by returning a reference to itself. For example: Matrix4 mat = new Matrix4().trn(position).mul(camera.combined);

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