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1
There's a few extra options I added like changing the blending equations.
Java - 3D ProgrammingsrcredbookblendingBlendingTriangles.png 67.26K
48 downloads
/*
* Legend -------------------------------
* Key A = move leftTriangle left
* Key D = move leftTriangle right
* Key LEFT_ARROW = move rightTriangle left
* Key RIGHT_ARROW = move rightTriangle right
* Key SPACE = switches from drawing triangles on top of eachother
* Key B - changes the blending equation
*/
package redbook.blending;
import org.lwjgl.LWJGLException;
import org.lwjgl.input.Keyboard;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL14;
import org.lwjgl.util.glu.GLU;
import static org.lwjgl.opengl.GL11.*;
public class BlendingTriangles {
private static final int WIDTH = 800, HEIGHT = 600;
private static final DisplayMode DISPLAY_MODE = new DisplayMode(WIDTH, HEIGHT);
private static final String WINDOW_TITLE = "Blending Triangles Test";
private static final int FPS = 70; //frames per second
private boolean isRunning; //variable to tell if program is running or not
private float zTranslation = -12f;
//---------- Variables added for Blending Triangles test --------------//
private Triangle triangleLeft, triangleRight;
private final float VELOCITY = .2f;
private final float VELOCITY_ALPHA = .05f;
private boolean leftFirst = false;
private boolean keySpaceDown = false;
private boolean keyBlendingDown = false;
private int blendingEquationIndex;
private final int[] BLENDING_EQUATIONS = {
GL14.GL_FUNC_ADD,
GL14.GL_FUNC_SUBTRACT,
GL14.GL_FUNC_REVERSE_SUBTRACT,
GL14.GL_MIN,
GL14.GL_MAX};
//---------- End - Variables added for Blending Triangles Test ------------//
public static void main(String[] args) {
BlendingTriangles test = new BlendingTriangles();
test.run();
}
private void run() {
try {
init();
while( isRunning ) {
getInput(); //read input
render(); //render graphics
Display.sync(FPS); //sync to fps
Display.update(); //update the view/screen
}
} catch (Exception e) {
e.printStackTrace();
System.exit(1);
}
}
private void render() {
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glLoadIdentity();
glTranslatef(0.0f, 0.0f, zTranslation);
if(leftFirst) {
drawTriangle(triangleLeft);
drawTriangle(triangleRight);
} else {
drawTriangle(triangleRight);
drawTriangle(triangleLeft);
}
}
//------------Method added for Blending Triangles Test----------//
private void drawTriangle(Triangle triangle) {
glBegin(GL_TRIANGLES); {
glColor4f(triangle.r, triangle.g, triangle.b, triangle.a);
glVertex3f(triangle.x, triangle.y, triangle.z);
glVertex3f(triangle.x+2, triangle.y, triangle.z);
glVertex3f(triangle.x+1, triangle.y+1, triangle.z);
}glEnd();
}
//------------End - Method added for Blending Triangles Test----------//
private void getInput() {
if(Keyboard.isKeyDown(Keyboard.KEY_ESCAPE)) { // if user presses escape key
isRunning = false;
}
if( Display.isCloseRequested()) { // if user closes window
isRunning = false;
}
//------------Moves triangles left or right--------------//
if( Keyboard.isKeyDown(Keyboard.KEY_A)) {
triangleLeft.x -= VELOCITY;
}
if( Keyboard.isKeyDown(Keyboard.KEY_D)) {
triangleLeft.x += VELOCITY;
}
if( Keyboard.isKeyDown(Keyboard.KEY_LEFT)) {
triangleRight.x -= VELOCITY;
}
if( Keyboard.isKeyDown(Keyboard.KEY_RIGHT)) {
triangleRight.x += VELOCITY;
}
//------------End - Moves triangles left or right--------------//
//------------Changes triangles alpha values--------------//
if( Keyboard.isKeyDown(Keyboard.KEY_W)) {
triangleLeft.a += VELOCITY_ALPHA;
}
if( Keyboard.isKeyDown(Keyboard.KEY_S)) {
triangleLeft.a -= VELOCITY_ALPHA;
}
if( Keyboard.isKeyDown(Keyboard.KEY_UP)) {
triangleRight.a += VELOCITY_ALPHA;
}
if( Keyboard.isKeyDown(Keyboard.KEY_DOWN)) {
triangleRight.a -= VELOCITY_ALPHA;
}
//------------End - Changes triangles alpha values--------------//
//------------Switches between drawing triangleLeft over triangleRight--------------//
if( Keyboard.isKeyDown(Keyboard.KEY_SPACE) && !keySpaceDown) {
leftFirst = !leftFirst;
keySpaceDown = true;
log("leftFirst=" + leftFirst);
}
if( !Keyboard.isKeyDown(Keyboard.KEY_SPACE) && keySpaceDown) {
keySpaceDown = false;
}
//------------End - Switches between drawing triangleLeft over triangleRight--------------//
//------------Switches Blending Modes--------------//
if( Keyboard.isKeyDown(Keyboard.KEY_B) && !keyBlendingDown) {
blendingEquationIndex = (blendingEquationIndex==BLENDING_EQUATIONS.length-1)?0:blendingEquationIndex+1;
GL14.glBlendEquation(BLENDING_EQUATIONS[blendingEquationIndex]);
keyBlendingDown = true;
log("blendingEquationIndex=" + blendingEquationIndex);
}
if( !Keyboard.isKeyDown(Keyboard.KEY_B) && keyBlendingDown) {
keyBlendingDown = false;
}
//------------End - Switches Blending Modes--------------//
}
private void log(String s) {
System.out.println(s);
}
private void init() {
createWindow();
initGL();
initTriangles();
isRunning = true;
}
//------------Method added for Blending Triangles Test----------//
private void initTriangles() {
triangleLeft = new Triangle();
triangleRight = new Triangle();
triangleLeft.x = -2f;
triangleRight.x = 2f;
triangleLeft.r = 1.0f;
triangleLeft.g = 1.0f;
triangleLeft.b = 0.0f;
triangleLeft.a = 0.75f;
triangleRight.r = 0.0f;
triangleRight.g = 1.0f;
triangleRight.b = 1.0f;
triangleRight.a = 0.75f;
}
//------------End - Method added for Blending Triangles Test----------//
private void createWindow() {
try {
Display.setDisplayMode(DISPLAY_MODE);
Display.setTitle(WINDOW_TITLE);
Display.create();
} catch (LWJGLException e){
e.printStackTrace();
}
}
private void initGL() {
glClearColor(0.5f, 0.5f, 0.5f, 0.0f); // sets background to grey
glClearDepth(1.0f); // clear depth buffer
glEnable(GL_DEPTH_TEST); // Enables depth testing
glDepthFunc(GL_LEQUAL); // sets the type of test to use for depth testing
glMatrixMode(GL_PROJECTION); // sets the matrix mode to project
float fovy = 45.0f;
float aspect = DISPLAY_MODE.getWidth() / (float)DISPLAY_MODE.getHeight();
float zNear = 0.1f;
float zFar = 100.0f;
GLU.gluPerspective(fovy, aspect, zNear, zFar);
glMatrixMode(GL_MODELVIEW);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
//---------Code added to enable and set up blending function----------//
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
GL14.glBlendEquation( BLENDING_EQUATIONS[blendingEquationIndex]);
glShadeModel(GL_FLAT);
//---------End - Code added to enable and set up blending function----------//
}
//----------Class added for Triangle Blending Test -----------//
private class Triangle {
float x, y, z; //refers to bottom left corner of a rightside up triangle
float r, g, b, a; //red, green, blue, alpha
}
//----------End - Class added for Triangle Blending Test -----------//
}
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