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/*
 * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 */

package javax.media.j3d;


/**
 * The ScreenViewCache class is used to cache all API data
 * from the Screen3D object.
 */
class ScreenViewCache extends Object {
    // The screen associated with this screen view cache
    Screen3D screen;

    //
    // API/INPUT DATA
    //

    // The width and height of the screen in meters.
    double physicalScreenWidth;
    double physicalScreenHeight;

    // The width and height of the screen in pixels.
    int screenWidth;
    int screenHeight;

    // Mask that indicates Screen3D view dependence info. has changed,
    // and CanvasViewCache may need to recompute the final view matries.
    // Issue 163: Array of dirty bits is used because the Renderer and
    // RenderBin run asynchronously. Now that they each have a separate
    // instance of CanvasViewCache (due to the fix for Issue 109), they
    // need separate dirty bits. Array element 0 is used for the Renderer and
    // element 1 is used for the RenderBin.
    int[] scrvcDirtyMask = new int[2];

    //
    // Tracker-base coordinate system to image-plate coordinate
    // system transform.  If head tracking is enabled, this transform
    // is a calibration constant.  If head tracking is not enabled,
    // this transform is not used.
    // This is used only in SCREEN_VIEW mode.
    //
    Transform3D trackerBaseToImagePlate = new Transform3D();

    //
    // Head-tracker coordinate system to left and right image-plate coordinate
    // system transforms.  If head tracking is enabled, these transforms
    // are calibration constants.  If head tracking is not enabled,
    // these transforms are not used.
    // These are used only in HMD_VIEW mode.
    //
    Transform3D headTrackerToLeftImagePlate = new Transform3D();
    Transform3D headTrackerToRightImagePlate = new Transform3D();


    //
    // DERIVED DATA
    //

    // Meters per pixel in the X and Y dimension
    double metersPerPixelX;
    double metersPerPixelY;


    /**
     * Take snapshot of all per-screen API parameters.
     */
    synchronized void snapshot() {

        // accumulate the dirty bits for offscreen because
        // the dirty bits will not be processed until renderOffScreen
        // or triggered by RenderBin at some little time
        if (screen.offScreen) {
            scrvcDirtyMask[0] |= screen.scrDirtyMask;
            scrvcDirtyMask[1] |= screen.scrDirtyMask;
        } else {
            scrvcDirtyMask[0] = screen.scrDirtyMask;
            scrvcDirtyMask[1] = screen.scrDirtyMask;
        }
        screen.scrDirtyMask = 0;

        physicalScreenWidth = screen.physicalScreenWidth;
	physicalScreenHeight = screen.physicalScreenHeight;
	screenWidth = screen.screenSize.width;
	screenHeight = screen.screenSize.height;

	screen.trackerBaseToImagePlate.getWithLock(trackerBaseToImagePlate);

	screen.headTrackerToLeftImagePlate.getWithLock
	    (headTrackerToLeftImagePlate);
	screen.headTrackerToRightImagePlate.getWithLock
	    (headTrackerToRightImagePlate);

	// This isn't really API data, but since we have no other derived
	// data, and it's a simple calculation, it's easier if we just do
	// it here.
	metersPerPixelX = physicalScreenWidth / (double) screenWidth;
	metersPerPixelY = physicalScreenHeight / (double) screenHeight;
    }


    /**
     * Constructs and initializes a ScreenViewCache object.
     */
    ScreenViewCache(Screen3D screen) {
	this.screen = screen;

	if (false)
	    System.err.println("Constructed a ScreenViewCache");
    }
}