org.jogamp.glg2d.impl.gl2.GL2Transformhelper.java Source code

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Here is the source code for org.jogamp.glg2d.impl.gl2.GL2Transformhelper.java

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/*
 * Copyright 2013 Brandon Borkholder
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jogamp.glg2d.impl.gl2;

import java.awt.geom.AffineTransform;

import org.lwjgl.opengl.GL11;
import org.lwjgl.opengl.GLContext;

import org.jogamp.glg2d.GLGraphics2D;
import org.jogamp.glg2d.impl.AbstractMatrixHelper;

import org.lwjgl.BufferUtils;
import java.nio.IntBuffer;
import java.nio.FloatBuffer;

public class GL2Transformhelper extends AbstractMatrixHelper {
    protected GLContext context;

    private FloatBuffer matrixBuf = BufferUtils.createFloatBuffer(16);

    @Override
    public void setG2D(GLGraphics2D g2d) {
        super.setG2D(g2d);
        context = g2d.getGLContext();

        setupGLView();
        flushTransformToOpenGL();
    }

    protected void setupGLView() {
        IntBuffer viewportDimensions = BufferUtils.createIntBuffer(16);
        GL11.glGetInteger(GL11.GL_VIEWPORT, viewportDimensions);
        int width = viewportDimensions.get(2);
        int height = viewportDimensions.get(3);

        // setup projection
        GL11.glMatrixMode(GL11.GL_PROJECTION);
        GL11.glLoadIdentity();
        GL11.glOrtho(0, width, 0, height, -1, 1);

        // the MODELVIEW matrix will get adjusted later

        GL11.glMatrixMode(GL11.GL_TEXTURE);
        GL11.glLoadIdentity();
    }

    /**
     * Sends the {@code AffineTransform} that's on top of the stack to the video
     * card.
     */
    protected void flushTransformToOpenGL() {
        FloatBuffer matrix = getGLMatrix(stack.peek());

        GL11.glMatrixMode(GL11.GL_MODELVIEW);
        GL11.glLoadMatrix(matrix);
    }

    /**
     * Gets the GL matrix for the {@code AffineTransform} with the change of
     * coordinates inlined. Since Java2D uses the upper-left as 0,0 and OpenGL
     * uses the lower-left as 0,0, we have to pre-multiply the matrix before
     * loading it onto the video card.
     */
    protected FloatBuffer getGLMatrix(AffineTransform transform) {
        matrixBuf.clear();
        BufferUtils.zeroBuffer(matrixBuf);
        matrixBuf.put(0, (float) transform.getScaleX());
        matrixBuf.put(1, -(float) transform.getShearY());
        matrixBuf.put(4, (float) transform.getShearX());
        matrixBuf.put(5, -(float) transform.getScaleY());
        matrixBuf.put(10, 1);
        matrixBuf.put(12, (float) transform.getTranslateX());
        matrixBuf.put(13, g2d.getCanvasHeight() - (float) transform.getTranslateY());
        matrixBuf.put(15, 1);

        return matrixBuf;
    }
}