[jGL] support SWT as a native renderer for jGL #192

- use canvas instead of GL-Canvas for now
- adapt Snippet195 to use jGL render

jzy3d-emul-gl-swt/src/test/java/org/jzy3d/swt/Snippet195.java

@@ -0,0 +1,133 @@
+/*******************************************************************************
+ * Copyright (c) 2000, 2021 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
+ * Christoph Läubrich - adapt example to use jGL
+ *******************************************************************************/
+package org.jzy3d.swt;
+
+/*
+ * SWT OpenGL snippet: use LWJGL to draw to an SWT GLCanvas
+ *
+ * For a list of all SWT example snippets see
+ * http://www.eclipse.org/swt/snippets/
+ *
+ * @since 3.2
+ */
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.layout.FillLayout;
+import org.eclipse.swt.opengl.GLData;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Shell;
+
+import jgl.wt.swt.GL;
+import jgl.wt.swt.JGLCanvas;
+
+public class Snippet195 {
+
+	static void drawTorus(GL gl, 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);
+			gl.glBegin(GL.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;
+				gl.glNormal3f(cosTheta1 * cosPhi, -sinTheta1 * cosPhi, sinPhi);
+				gl.glVertex3f(cosTheta1 * dist, -sinTheta1 * dist, r * sinPhi);
+				gl.glNormal3f(cosTheta * cosPhi, -sinTheta * cosPhi, sinPhi);
+				gl.glVertex3f(cosTheta * dist, -sinTheta * dist, r * sinPhi);
+			}
+			gl.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 FillLayout());
+		Composite comp = new Composite(shell, SWT.NONE);
+		comp.setLayout(new FillLayout());
+		GLData data = new GLData ();
+		data.doubleBuffer = true;
+		final JGLCanvas canvas = new JGLCanvas(comp, SWT.NONE, data);
+		canvas.addListener(SWT.Resize, event -> {
+			Rectangle bounds = canvas.getBounds();
+			GL gl = canvas.getGL();
+			float fAspect = (float)bounds.width / (float)bounds.height;
+			gl.glViewport(0, 0, bounds.width, bounds.height);
+			gl.glMatrixMode(GL.GL_PROJECTION);
+			gl.glLoadIdentity();
+			float near = 0.5f;
+			float bottom = -near * (float)Math.tan(45.f / 2);
+			float left = fAspect * bottom;
+			gl.glFrustum(left, -left, bottom, -bottom, near, 400.f);
+			gl.glMatrixMode(GL.GL_MODELVIEW);
+			gl.glLoadIdentity();
+		});
+		canvas.setCurrent();
+
+		GL gl = canvas.getGL();
+		gl.glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
+		gl.glColor3f(1.0f, 0.0f, 0.0f);
+		// TODO ? gl.glHint(GL.GL_PERSPECTIVE_CORRECTION_HINT, gl.GL_NICEST);
+		gl.glClearDepth(1.0);
+		gl.glLineWidth(2);
+		gl.glEnable(GL.GL_DEPTH_TEST);
+
+		shell.setText("SWT/Adopted LWJGL Example");
+		shell.setSize(640, 480);
+		shell.open();
+
+		final Runnable run = new Runnable() {
+			int rot = 0;
+			@Override
+			public void run() {
+				if (!canvas.isDisposed()) {
+					GL gl = canvas.getGL();
+					canvas.setCurrent();
+					gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
+					gl.glClearColor(.3f, .5f, .8f, 1.0f);
+					gl.glLoadIdentity();
+					gl.glTranslatef(0.0f, 0.0f, -10.0f);
+					float frot = rot;
+					gl.glRotatef(0.15f * rot, 2.0f * frot, 10.0f * frot, 1.0f);
+					gl.glRotatef(0.3f * rot, 3.0f * frot, 1.0f * frot, 1.0f);
+					rot++;
+					gl.glPolygonMode(GL.GL_FRONT_AND_BACK, GL.GL_LINE);
+					gl.glColor3f(0.9f, 0.9f, 0.9f);
+					drawTorus(gl, 1, 1.9f + ((float)Math.sin((0.004f * frot))), 15, 15);
+					canvas.swapBuffers();
+					display.timerExec(10, this);
+				}
+			}
+		};
+		display.asyncExec(run);
+
+		while (!shell.isDisposed()) {
+			if (!display.readAndDispatch())
+				display.sleep();
+		}
+		display.dispose();
+	}
+}

jzy3d-jGL/src/main/java/jgl/wt/swt/JGLCanvas.java

@@ -17,17 +17,17 @@ import org.eclipse.swt.events.ControlListener;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Point;
-import org.eclipse.swt.opengl.GLCanvas;
 import org.eclipse.swt.opengl.GLData;
+import org.eclipse.swt.widgets.Canvas;
 import org.eclipse.swt.widgets.Composite;
 
-public class JGLCanvas extends GLCanvas {
+public class JGLCanvas extends Canvas {
 
 	protected GL gl;
 
 	public JGLCanvas(Composite parent, int style, GLData data) {
 
-		super(parent, style, data);
+		super(parent, style);
 		gl = new GL(parent.getDisplay());
 		parent.addDisposeListener(e -> gl.dispose());
 		gl.setAutoAdaptToHiDPI(false);
@@ -41,7 +41,6 @@ public class JGLCanvas extends GLCanvas {
 				doResize(size.x, size.y);
 			}
 
-
 			@Override
 			public void controlMoved(ControlEvent e) {
 
@@ -73,16 +72,14 @@ public class JGLCanvas extends GLCanvas {
 		return gl;
 	}
 
-	@Override
 	public void setCurrent() {
 
-		super.setCurrent();
+		// no-opp just for compatibility reasons
 	}
 
-	@Override
 	public void swapBuffers() {
 
-		super.swapBuffers();
+		gl.glFlush();
+		redraw();
 	}
-
 }