New topic for Java course: Introduction to 3D graphics programming

Transcription

1 New topic for Java course: Introduction to 3D graphics programming with JOGL Dejan Mitrović Prof. Dr Mirjana Ivanović AGENDA 1. Motivation and goals 2. JOGL 3. Proposed subjects 4. Conclusions 2/29 1

2 1.1. Motivation Game development represents a large portion of the software development industry, BUT, so far very few programming courses given at our Department were focused at this area The proposed set of subjects constitutes a small part of the recently updated Computer graphics course, which has received high grades from students 3/ Goals Provide students with an opportunity to practice Java programming and extend their OO programming skills in an exciting environment Introduce the proposed set of subjects near the end of the introductory, or at the beginning of the advanced OO course, depending on the students progress over the semester Give them a solid background for later, more advanced topics of the Computer graphics course 4/29 2

3 AGENDA 1. Motivation and goals 2. JOGL 3. Proposed subjects 4. Conclusions 5/ Why JOGL? Based on OpenGL a professional, powerful, free, crossplatform graphics programming library Straightforward integration with other GUI and graphics Java APIs and libraries (e.g. Swing, Java2D) Can serve as an example of how an OO system should not be designed 6/29 3

4 2.2. JOGLext: A JOGL extension library A library of helper classes built on top of JOGL Handles common, boring, but necessary tasks, includes functions for vector and matrix based calculations, etc. Purpose: enable students to develop simple 3D applications without any (mathematical or game programming) background Although, experience in playing FPS games can prove valuable for 3D camera handling 7/ Core JOGLext classes JoglFrame: a base class for all students applications, handles display mode changes, precise timing measurements, various maintenance tasks, etc. Camera: a flexible, programmable, FPS like 3D camera for navigation through generated scenes Mesh: a framework for loading and rendering external complex 3D models 8/29 4

5 AGENDA 1. Motivation and goals 2. JOGL 3. Proposed subjects 4. Conclusions 9/29 3. Proposed subjects 1. Introduction to 3D graphics programming (1 hour lesson) 2. 3D rendering basics (1 hour lesson) 3. World transformations (2 hours lesson) 4. Texturing (2 hours lesson) 5. Complex 3D models (2 hours lesson) 10/29 5

6 3.1. Introduction to 3D graphics programming What is a graphics programming library? Introduction to OpenGL and JOGL Elements of a 3D application: frustum definition, overview of projection and viewing transformations, viewports, etc. Main classes of JOGLext, creating a very first 3D application by implementing methods of JoglFrame 11/ Example: HelloWorld3D public class HelloWorld3D extends protected void initialize(gl gl, Color4f back, Vector3f camerapos, Vector3f cameradir) // TODO : initialize camera, set clear protected void render(gl gl, double elapsedtime) // TODO : perform rendering public static void main(string[] args) HelloWorld3D hw = new HelloWorld3D(); // Caption: Hello World 3D // Frame width: 640px // Frame height: 480px // Fullscreen mode: false hw.start("hello World 3D", 640, 480, false); 12/29 6

7 3.1. Results 13/ D rendering basics Coordinate system and 3D object specification using vertices Methods glvertex3f() and glcolor3f() Different modes of rendering with glbegin() and glend(): triangle lists, strips, and fans, quads, and polygons Rendering built in objects with GLUT Basic 2D text rendering with TextRenderer 14/29 7

8 3.2. Example: Hexagon public class Hexagon // vertices definition private static final Vector3f[] vertices = new Vector3f[] new Vector3f( 0.0f, 0.0f, 0.0f), new Vector3f(-1.0f, 0.0f, 0.0f), new Vector3f(-0.5f, 1.0f, 0.0f), new Vector3f( 0.5f, 1.0f, 0.0f), new Vector3f( 1.0f, 0.0f, 0.0f), new Vector3f( 0.5f, -1.0f, 0.0f), new Vector3f(-0.5f, -1.0f, 0.0f) ; // each vertex will be of a different color private static final Color4f[] colors = new Color4f[] new Color4f(1.0f, 0.0f, 0.0f), new Color4f(0.0f, 1.0f, 0.0f), new Color4f(1.0f, 1.0f, 0.0f), new Color4f(1.0f, 1.0f, 1.0f), new Color4f(0.0f, 0.0f, 1.0f), new Color4f(1.0f, 0.0f, 1.0f), new Color4f(0.0f, 1.0f, 1.0f) ; 15/ Example: Hexagon (cont.) // method for rendering the n-th vertex private void renderpoint(gl gl, int n, float z) // first set the n-th color, then send the coordinates Color4f c = colors[n]; gl.glcolor3f(c.getred(), c.getgreen(), c.getblue()); Vector3f v = vertices[n]; gl.glvertex3f(v.getx(), v.gety(), z); // using GL_TRIANGLE_FAN for hexagon rendering public void rendertrianglefan(gl gl, float z) // the first 3 vertices make up 1 triangle // every other vertex is connected to the first and the the previous one gl.glbegin(gl.gl_triangle_fan); renderpoint(gl, 0, z); renderpoint(gl, 1, z); renderpoint(gl, 2, z); renderpoint(gl, 3, z); renderpoint(gl, 4, z); renderpoint(gl, 5, z); renderpoint(gl, 6, z); renderpoint(gl, 1, z); gl.glend(); // class Hexagon 16/29 8

9 3.2. Example: 3D Rendering public class HelloWorld3D extends JoglFrame private Hexagon hex = new Hexagon(); private TextRenderer protected void initialize(gl gl, Color4f back, Vector3f camerapos, Vector3f cameradir) // initialize TextRenderer Font font = new Font("Tahoma", Font.BOLD, 12); text = new protected void render(gl gl, double elapsedtime) // render a yellow teapot using GLUT gl.glcolor3f(1.0f, 1.0f, 0.0f); glut.glutsolidteapot(1.0f); // render a colored triangle behind the teapot gl.glbegin(gl.gl_triangles); gl.glcolor3f( 1.0f, 0.0f, 0.0f); gl.glvertex3f(-1.0f, -0.5f, -5.0f); gl.glcolor3f( 0.0f, 1.0f, 0.0f); gl.glvertex3f( 1.0f, -0.5f, -5.0f); gl.glcolor3f( 1.0f, 1.0f, 1.0f); gl.glvertex3f( 0.0f, 0.5f, -5.0f); gl.glend(); 17/ Example: 3D Rendering (cont.) // render a hexagon behind the triangle hex.rendertrianglefan(gl, -10.0f); // render 2D text at the top of the window int w = getwidth(); int h = getheight(); text.beginrendering(w, h); text.setcolor(1.0f, 1.0f, 0.0f, 1.0f); // first line - frame rate, below it - camera position text.draw("fps: " + getfps(), 2, h - 16); text.draw("camera: " + camera.getposition().tostring(), 2, h - 36); // end text rendering text.endrendering(); // render public static void main(string[] args) HelloWorld3D hw = new HelloWorld3D(); hw.start("hello World 3D", 640, 480, false); // class HelloWorld3D 18/29 9

10 3.2. Results 19/ World transformations Motivation behind and the effects of world transformations With just a brief overview of low level matrix math Methods gltranslatef(), glrotatef(), and glscalef() Combining multiple transformations Storing and restoring transformations with glpushmatrix() and glpopmatrix() 20/29 10

11 3.3. Example: SolarSystem public class Planet private float distance; // from the sun private float revolution; // revolution angle private float scale; // size parameter private Color4f color; // color of the planet public Planet(float distance, float revolution, float scale, Color4f color) // ommitted, save parameters public void render(gl gl, GLUT glut) // set the planet color gl.glcolor3f(color.getred(), color.getgreen(), color.getblue()); // every method that changes the world transformation // should always first save the current state and later restore it gl.glpushmatrix(); // rotation around the sun gl.glrotatef(revolution, 0.0f, 1.0f, 0.0f); gl.gltranslatef(distance, 0.0f, 0.0f); // scale the sphere and render it gl.glscalef(scale, scale, scale); glut.glutsolidsphere(1.0f, 25, 25); // restore the original world transformation gl.glpopmatrix(); 21/ Example: SolarSystem (cont.) public class SolarSystem extends JoglFrame private Planet sun, venus, earth, mars; // miniature solar system protected void initialize(gl gl, Color4f backcolor, Vector3f camerapos, Vector3f cameradir) // initialize camera camerapos.assign(1.75f, 17.0f, 38.47f); cameradir.assign(0.0f, -0.49f, -0.87f); // initialize planets sun = new Planet(0.0f, 0.0f, 5.0f, new Color4f(1.0f, 1.0f, 0.0f)); venus = new Planet(10.0f, f, 0.7f, new Color4f(0.59f, 0.3f, 0.0f)); earth = new Planet(15.0f, -80.0f, 1.0f, new Color4f(0.0f, 0.0f, 1.0f)); mars = new Planet(20.0f, -60.0f, 0.5f, new Color4f(1.0f, 0.0f, 0.0f)); protected void render(gl gl, double elapsedtime) sun.render(gl, glut); venus.render(gl, glut); earth.render(gl, glut); mars.render(gl, glut); public static void main(string[] args) // ommitted, the usual 22/29 11

12 3.3. Results 23/ Texturing Textures and texture coordinates Loading, enabling, disabling, and binding textures, assigning coordinates with gltexcoord2f() Method gltexenvf(), and environment modes GL_MODULATE and GL_REPLACE Different ways of applying texture coordinates with GL_CLAMP and GL_REPEAT 2D texture rendering with TextureRenderer 24/29 12

13 3.4. Adding textures to SolarSystem 25/ Complex 3D models The concept of meshes, their organization into submeshes of vertices with shared properties Using the Mesh class for loading and rendering 3D models OBJ file format for storing meshes 26/29 13

14 3.5. The end results 27/29 4. Conclusions Graphics programming with JOGL represents an exciting environment for practicing Java programming and extending students OO programming skills (such as aggregation, inheritance and polymorphism, working with arrays, etc.) JOGLext enables students to dive into the 3D application development without much previous knowledge of the subject The proposed set of subjects is simple enough, yet it provides them with enough material for creating real 3D applications The subjects also serve as a good foundation for senior, more advance Computer graphics course 28/29 14

15 Thank you! Questions? Suggestions? 29/29 15