Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2019 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.snippets; /* * SWT OpenGL snippet: capture a LWJGL drawing to an SWT Image * * This example is essentially Snippet195 with the capture() method * added. It should be easily adaptable to other OpenGL packages. * * For a list of all SWT example snippets see * http://www.eclipse.org/swt/snippets/ * * @since 3.2 */ import java.nio.*; import org.eclipse.swt.*; import org.eclipse.swt.graphics.*; import org.eclipse.swt.layout.*; import org.eclipse.swt.opengl.*; import org.eclipse.swt.widgets.*; import org.lwjgl.opengl.*; public class Snippet341 { static void drawTorus(float r, float R, int nsides, int rings) { float ringDelta = 2.0f * (float) Math.PI / rings; float sideDelta = 2.0f * (float) Math.PI / nsides; float theta = 0.0f, cosTheta = 1.0f, sinTheta = 0.0f; for (int i = rings - 1; i >= 0; i--) { float theta1 = theta + ringDelta; float cosTheta1 = (float) Math.cos(theta1); float sinTheta1 = (float) Math.sin(theta1); GL11.glBegin(GL11.GL_QUAD_STRIP); float phi = 0.0f; for (int j = nsides; j >= 0; j--) { phi += sideDelta; float cosPhi = (float) Math.cos(phi); float sinPhi = (float) Math.sin(phi); float dist = R + r * cosPhi; GL11.glNormal3f(cosTheta1 * cosPhi, -sinTheta1 * cosPhi, sinPhi); GL11.glVertex3f(cosTheta1 * dist, -sinTheta1 * dist, r * sinPhi); GL11.glNormal3f(cosTheta * cosPhi, -sinTheta * cosPhi, sinPhi); GL11.glVertex3f(cosTheta * dist, -sinTheta * dist, r * sinPhi); } GL11.glEnd(); theta = theta1; cosTheta = cosTheta1; sinTheta = sinTheta1; } } public static void main(String[] args) { final Display display = new Display(); Shell shell = new Shell(display); shell.setLayout(new FormLayout()); GLData data = new GLData(); data.doubleBuffer = true; final GLCanvas canvas = new GLCanvas(shell, SWT.NONE, data); canvas.setCurrent(); GL.createCapabilities(); canvas.addListener(SWT.Resize, event -> { Rectangle bounds = canvas.getBounds(); float fAspect = (float) bounds.width / (float) bounds.height; canvas.setCurrent(); GL.createCapabilities(); GL11.glViewport(0, 0, bounds.width, bounds.height); GL11.glMatrixMode(GL11.GL_PROJECTION); GL11.glLoadIdentity(); float near = 0.5f; float bottom = -near * (float) Math.tan(45.f / 2); float left = fAspect * bottom; GL11.glFrustum(left, -left, bottom, -bottom, near, 400.f); GL11.glMatrixMode(GL11.GL_MODELVIEW); GL11.glLoadIdentity(); }); GL11.glClearColor(1.0f, 1.0f, 1.0f, 1.0f); GL11.glColor3f(1.0f, 0.0f, 0.0f); GL11.glHint(GL11.GL_PERSPECTIVE_CORRECTION_HINT, GL11.GL_NICEST); GL11.glClearDepth(1.0); GL11.glLineWidth(2); GL11.glEnable(GL11.GL_DEPTH_TEST); Button button = new Button(shell, SWT.PUSH); button.setText("Capture"); button.addListener(SWT.Selection, event -> capture(canvas)); FormData formData = new FormData(640, 480); formData.top = new FormAttachment(0, 0); formData.left = new FormAttachment(0, 0); formData.bottom = new FormAttachment(button, 0); formData.right = new FormAttachment(100, 0); canvas.setLayoutData(formData); formData = new FormData(); formData.left = new FormAttachment(0, 0); formData.bottom = new FormAttachment(100, 0); formData.right = new FormAttachment(100, 0); button.setLayoutData(formData); shell.pack(); shell.open(); display.asyncExec(new Runnable() { int rot = 0; @Override public void run() { if (!canvas.isDisposed()) { canvas.setCurrent(); GL.createCapabilities(); GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT); GL11.glClearColor(.3f, .5f, .8f, 1.0f); GL11.glLoadIdentity(); GL11.glTranslatef(0.0f, 0.0f, -10.0f); float frot = rot; GL11.glRotatef(0.15f * rot, 2.0f * frot, 10.0f * frot, 1.0f); GL11.glRotatef(0.3f * rot, 3.0f * frot, 1.0f * frot, 1.0f); rot++; GL11.glPolygonMode(GL11.GL_FRONT_AND_BACK, GL11.GL_LINE); GL11.glColor3f(0.9f, 0.9f, 0.9f); drawTorus(1, 1.9f + ((float) Math.sin((0.004f * frot))), 15, 15); canvas.swapBuffers(); display.asyncExec(this); } } }); while (!shell.isDisposed()) { if (!display.readAndDispatch()) display.sleep(); } display.dispose(); } static void capture(GLCanvas glCanvas) { final int PAD = 4; Display display = glCanvas.getDisplay(); Rectangle bounds = glCanvas.getBounds(); int size = bounds.width * PAD * bounds.height; ByteBuffer buffer = ByteBuffer.allocateDirect(size); GL11.glReadPixels(0, 0, bounds.width, bounds.height, GL11.GL_RGBA, GL11.GL_UNSIGNED_BYTE, buffer); byte[] bytes = new byte[size]; buffer.get(bytes); /* * In OpenGL (0,0) is at the bottom-left corner, and y values ascend in the upward * direction. This is opposite to SWT which defines (0,0) to be at the top-left * corner with y values ascendingin the downwards direction. Re-order the OpenGL- * provided bytes to SWT's expected order so that the Image will not appear inverted. */ byte[] temp = new byte[bytes.length]; for (int i = 0; i < bytes.length; i += bounds.width * PAD) { System.arraycopy(bytes, bytes.length - i - bounds.width * PAD, temp, i, bounds.width * PAD); } bytes = temp; ImageData data = new ImageData(bounds.width, bounds.height, 32, new PaletteData(0xFF000000, 0xFF0000, 0xFF00), PAD, bytes); final Image image = new Image(display, data); Shell shell = new Shell(display); shell.setLayout(new GridLayout()); Canvas canvas = new Canvas(shell, SWT.NONE); canvas.setLayoutData(new GridData(bounds.width, bounds.height)); canvas.addListener(SWT.Paint, event -> event.gc.drawImage(image, 0, 0)); shell.pack(); shell.open(); shell.addListener(SWT.Dispose, event -> image.dispose()); } }