/*
* Copyright (c) 2013, Oskar Veerhoek
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation are those
* of the authors and should not be interpreted as representing official policies,
* either expressed or implied, of the FreeBSD Project.
*/
package future;
import org.lwjgl.LWJGLException;
import org.lwjgl.input.Mouse;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import static org.lwjgl.opengl.GL11.*;
/**
* Shows how to use OpenGL scissoring to render a specific part of the viewport. Press the left mouse button to drag the
* bottom-left corner of the scissor box. Press the right mouse button to drag the upper-right corner of the scissor
* box.
*
* @author Oskar Veerhoek
*/
public class ScissorDemo {
private static final String WINDOW_TITLE = "Scissoring!";
private static final int[] WINDOW_DIMENSIONS = {640, 480};
/**
* The dimensions of the scissor box. [0] is the left x-coordinate of the scissor box [1] is the bottom y-coordinate
* of the scissor box [2] is the right x-coordinate of the scissor box [3] is the right y-coordinate of the scissor
* box
*/
private static final int[] scissorBox = {0, 0, WINDOW_DIMENSIONS[0], WINDOW_DIMENSIONS[1]};
/**
* The location of the mouse cursor relative to the application window. [0] is the x-coordinate of the mouse cursor
* (0 is left) [1] is the y-coordinate of the mouse cursor (0 is bottom)
*/
private static final int[] mouseLocation = {0, 0};
/**
* The mouse button which is being pressed. -1 stands for no mouse button 0 stands for the left mouse button 1
* stands for the right mouse button
*/
private static int mouseButtonPressed = -1;
public static void main(String[] args) {
setUpDisplay();
setUpStates();
enterGameLoop();
cleanUp(false);
}
private static void render() {
// Fills the entire window (or scissor box) with black.
glClear(GL_COLOR_BUFFER_BIT);
/**
* The left x-coordinate of the scissor box.
*/
int scissorX = scissorBox[0];
/**
* The bottom y-coordinate of the scissor box.
*/
int scissorY = scissorBox[1];
/**
* The width of the scissor box. May be negative.
*/
int scissorWidth = scissorBox[2] - scissorBox[0];
/**
* The height of the scissor box. May be negative.
*/
int scissorHeight = scissorBox[3] - scissorBox[1];
// If scissorWidth and scissorHeight are not negative ...
/* If the width and height of the scissor box are negative. */
boolean scissorInverted = false;
if (scissorWidth >= 0 && scissorHeight >= 0) {
// Specify the scissor box.
glScissor(scissorX, scissorY, scissorWidth, scissorHeight);
// Fill the entire window with white. Due to scissoring
// only the an area that is equal to the scissor box will
// be drawn.
glRectf(-1, -1, 1, 1);
// Since scissorWidth and scissorHeight are not negative,
// set scissorInverted to false.
scissorInverted = false;
} else {
// Since scissorWidth and scissorHeight are negative,
// set scissorInverted to false.
scissorInverted = true;
}
glScissor(0, 0, WINDOW_DIMENSIONS[0], WINDOW_DIMENSIONS[1]);
glPushAttrib(GL_CURRENT_BIT);
if (scissorInverted) {
glColor3f(1, 0, 0);
} else {
glColor3f(0, 1, 0);
}
glBegin(GL_POINTS);
glVertex2f(scissorBox[0] / (WINDOW_DIMENSIONS[0] / 2f) - 1, scissorBox[1] / (WINDOW_DIMENSIONS[1] / 2f) - 1);
glVertex2f(scissorBox[2] / (WINDOW_DIMENSIONS[0] / 2f) - 1, scissorBox[3] / (WINDOW_DIMENSIONS[1] / 2f) - 1);
glEnd();
glPopAttrib();
}
private static void logic() {
if (mouseButtonPressed == 0) {
scissorBox[0] = mouseLocation[0];
scissorBox[1] = mouseLocation[1];
} else if (mouseButtonPressed == 1) {
scissorBox[2] = mouseLocation[0];
scissorBox[3] = mouseLocation[1];
}
}
private static void input() {
mouseLocation[0] = Mouse.getX();
mouseLocation[1] = Mouse.getY();
if (Mouse.isButtonDown(0) && !Mouse.isButtonDown(1)) {
mouseButtonPressed = 0;
} else if (Mouse.isButtonDown(1) && !Mouse.isButtonDown(0)) {
mouseButtonPressed = 1;
} else {
mouseButtonPressed = -1;
}
}
private static void cleanUp(boolean asCrash) {
Display.destroy();
System.exit(asCrash ? 1 : 0);
}
private static void setUpStates() {
glEnable(GL_SCISSOR_TEST);
glPointSize(25);
}
private static void update() {
Display.update();
Display.sync(60);
}
private static void enterGameLoop() {
while (!Display.isCloseRequested()) {
render();
logic();
input();
update();
}
}
private static void setUpDisplay() {
try {
Display.setDisplayMode(new DisplayMode(WINDOW_DIMENSIONS[0], WINDOW_DIMENSIONS[1]));
Display.setVSyncEnabled(true);
Display.setTitle(WINDOW_TITLE);
Display.create();
} catch (LWJGLException e) {
e.printStackTrace();
cleanUp(true);
}
}
}