QuadExample.java

package com.company;

import org.lwjgl.LWJGLException;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL11;
import org.lwjgl.input.Keyboard;


public class QuadExample {


    public void start() {
        try {
            Display.setDisplayMode(new DisplayMode(800,600));
            Display.create();


        } catch (Exception e) {
            e.printStackTrace();
            System.exit(0);
        }

        // init OpenGL
        GL11.glMatrixMode(GL11.GL_PROJECTION);
        GL11.glLoadIdentity();
        GL11.glOrtho(0, 800, 0, 600, 1, -1);
        GL11.glMatrixMode(GL11.GL_MODELVIEW); //setting active matrix to model view



        while (!Display.isCloseRequested()) {
            GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);
            userLogic();
            rect.render();;
            triangle.render();
            stationaryRectangle.render();
            renderText();  //uncomment the commented parts and add actual text rendering code here


            Display.update();
        }


        Display.destroy();
    }




    MyRectangle rect = new MyRectangle(50, 250, 50, 50);
    MyEquiTriangle triangle = new MyEquiTriangle(50, 50, 50);
    StationaryRectangle stationaryRectangle = new StationaryRectangle(400, 400, 90, 90);


    public void userLogic() {

        if (Keyboard.isKeyDown(Keyboard.KEY_A)) {
            rect.setLocation(rect.x - .1f, rect.y);
            rect.setRotation(rect.rotation-.5f);

        } else if (Keyboard.isKeyDown(Keyboard.KEY_D)) {
            rect.setLocation(rect.x + .1f, rect.y);
            rect.setRotation(rect.rotation+.5f);

        } if (Keyboard.isKeyDown(Keyboard.KEY_W)) {
            triangle.setLocation(triangle.x, triangle.y+.1f);
            triangle.setRotation(triangle.rotation-.5f);
        } else if (Keyboard.isKeyDown(Keyboard.KEY_S)) {
            triangle.setLocation(triangle.x, triangle.y-.1f);
            triangle.setRotation(triangle.rotation+.5f);
        }
    }


    private class MyEquiTriangle {
        float x, y;
        float rotation;
        float side;
        float vertX1, vertY1, vertX2, vertY2, vertx3, vertY3;
        public MyEquiTriangle(float xPos, float yPos, float sideLength) {
            x = xPos;
            y = yPos;
            vertX1 = -sideLength/2;  //things get a bit tricky here. You need to find the incircle
            vertX2 = sideLength/2;   // of a triangle to find it's symmetric rotation point.
            vertY1 = (float) -Math.sqrt(3) * sideLength/ 6f;  //Since this is an equilateral triangle, things
            vertY2 = (float) -Math.sqrt(3) * sideLength/ 6f;  //get a bit more easy
            vertx3 = 0;
            vertY3 = (float) Math.sqrt(3) * sideLength /3 ;

        }

        public void setLocation(float xPos, float yPos) {
            x = xPos;
            y = yPos;
            x = Math.max(0, x);
            x = Math.min(Display.getWidth(), x);
            y = Math.max(0, y);
            y = Math.min(Display.getHeight(), y);
        }

        public void setRotation(float rot) {
            rotation = rot;
            if(rotation>=360) {
                rotation-=360;
            }
            else if(rotation<0) {
                rotation+=360;
            }
        }

        public void render() {
            GL11.glLoadIdentity();
            GL11.glTranslatef(x, y, 0);
            GL11.glRotatef(rotation, 0, 0, 1);
            GL11.glScalef(1, 1, 1);
            GL11.glBegin(GL11.GL_TRIANGLES);
            GL11.glVertex2f(vertX1, vertY1);
            GL11.glVertex2f(vertX2, vertY2);
            GL11.glVertex2f(vertx3, vertY3);
            GL11.glEnd();
        }
    }


    private class MyRectangle {
        float x, y, width, height;
        float rotation;
        public MyRectangle(float posX, float posY, float w, float h) {
            x = posX;
            y = posY;
            width = w;
            height = h;

        }
        public void setLocation(float xPos, float yPos) {
            x = xPos;
            y = yPos;
            x = Math.max(0, x);
            x = Math.min(Display.getWidth(), x);
            y = Math.max(0, y);
            y = Math.min(Display.getHeight(), y);
        }

        public void setRotation(float rot) {
            rotation = rot;
            if(rotation>=360) {
                rotation-=360;
            }
            else if(rotation<0) {
                rotation+=360;
            }
        }

        public void render() {


            GL11.glLoadIdentity();
            GL11.glTranslatef(x, y, 0);
            GL11.glRotatef(rotation, 0, 0, 1);
            GL11.glScalef(1, 1, 1);
            GL11.glBegin(GL11.GL_QUADS);
            GL11.glVertex2f(-width / 2, -height / 2);
            GL11.glVertex2f(width / 2, -height / 2);
            GL11.glVertex2f(width / 2, height / 2);
            GL11.glVertex2f(-width / 2, height / 2);
            GL11.glEnd();

        }
    }


    private class StationaryRectangle {
        float x, y;
        float width, height;
        public StationaryRectangle (float posX, float posY, float w, float h){
            x = posX;
            y = posY;
            width = w;
            height = h;

        }

        public void render() {

            GL11.glLoadIdentity();
            GL11.glTranslatef(x, y, 0);
            GL11.glBegin(GL11.GL_QUADS);
            GL11.glVertex2f(-width / 2, -height / 2);
            GL11.glVertex2f(width / 2, -height / 2);
            GL11.glVertex2f(width / 2, height / 2);
            GL11.glVertex2f(-width / 2, height / 2);
            GL11.glEnd();

        }
    }

    public void renderText() {
        GL11.glLoadIdentity();
        //GL11.glTranslatef();
        //GL11.glRotatef();
        //GL11.glScalef();
        //draw text here

    }

    public static void main(String[] argv) {
        QuadExample quadExample = new QuadExample();
        quadExample.start();
    }
}