lwjglblendstate.java

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/*
 * Copyright (c) 2003-2009 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
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 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * 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.
 *
 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * 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
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.jme.scene.state.lwjgl;

import org.lwjgl.opengl.ARBImaging;
import org.lwjgl.opengl.EXTBlendColor;
import org.lwjgl.opengl.EXTBlendEquationSeparate;
import org.lwjgl.opengl.EXTBlendFuncSeparate;
import org.lwjgl.opengl.EXTBlendMinmax;
import org.lwjgl.opengl.EXTBlendSubtract;
import org.lwjgl.opengl.GL11;
import org.lwjgl.opengl.GLContext;

import com.jme.renderer.RenderContext;
import com.jme.scene.state.BlendState;
import com.jme.scene.state.lwjgl.records.BlendStateRecord;
import com.jme.system.DisplaySystem;

/**
 * <code>LWJGLBlendState</code> subclasses the BlendState using the LWJGL API
 * to set OpenGL's blending state params.
 * 
 * @author Mark Powell
 * @author Joshua Slack - reworked for StateRecords.
 * @version $Id: LWJGLBlendState.java,v 1.10 2007/04/11 18:27:36 nca Exp $
 */
public class LWJGLBlendState extends BlendState {
    private static final long serialVersionUID = 1L;

    private static boolean inited = false;

    /**
     * Constructor instantiates a new <code>LWJGLBlendState</code> object with
     * default values.
     */
    public LWJGLBlendState() {
        super();
        if (!inited) {
            supportsConstantColor = supportsEq = GLContext.getCapabilities().GL_ARB_imaging;
            supportsSeparateFunc = GLContext.getCapabilities().GL_EXT_blend_func_separate;
            supportsSeparateEq = GLContext.getCapabilities().GL_EXT_blend_equation_separate;
            supportsMinMax = GLContext.getCapabilities().GL_EXT_blend_minmax;
            supportsSubtract = GLContext.getCapabilities().GL_EXT_blend_subtract;

            // We're done initing! Wee! :)
            inited = true;
        }
    }

    /**
     * <code>apply</code> is called to set the blend state. If blending is
     * enabled, the blend function is set up and if alpha testing is enabled the
     * alpha functions are set.
     * 
     * @see com.jme.scene.state.RenderState#apply()
     */
    public void apply() {
        // ask for the current state record
        RenderContext<?> context = DisplaySystem.getDisplaySystem().getCurrentContext();
        BlendStateRecord record = (BlendStateRecord) context.getStateRecord(StateType.Blend);
        context.currentStates[StateType.Blend.ordinal()] = this;

        if (isEnabled()) {
            applyBlendEquations(isBlendEnabled(), record);
            applyBlendColor(isBlendEnabled(), record);
            applyBlendFunctions(isBlendEnabled(), record);

            applyTest(isTestEnabled(), record);
        } else {
            // disable blend
            applyBlendEquations(false, record);

            // disable alpha test
            applyTest(false, record);
        }

        if (!record.isValid())
            record.validate();
    }

    private void applyBlendEquations(boolean enabled, BlendStateRecord record) {
        if (record.isValid()) {
            if (enabled) {
                if (!record.blendEnabled) {
                    GL11.glEnable(GL11.GL_BLEND);
                    record.blendEnabled = true;
                }
                int blendEqRGB = getGLEquationValue(getBlendEquationRGB());
                if (supportsSeparateEquations()) {
                    int blendEqAlpha = getGLEquationValue(getBlendEquationAlpha());
                    if (record.blendEqRGB != blendEqRGB
                            || record.blendEqAlpha != blendEqAlpha) {
                        EXTBlendEquationSeparate.glBlendEquationSeparateEXT(
                                blendEqRGB, blendEqAlpha);
                        record.blendEqRGB = blendEqRGB;
                        record.blendEqAlpha = blendEqAlpha;
                    }
                } else if (supportsEq) {
                    if (record.blendEqRGB != blendEqRGB) {
                        ARBImaging.glBlendEquation(blendEqRGB);
                        record.blendEqRGB = blendEqRGB;
                    }
                }
            } else if (record.blendEnabled) {
                GL11.glDisable(GL11.GL_BLEND);
                record.blendEnabled = false;
            }

        } else {
            if (enabled) {
                GL11.glEnable(GL11.GL_BLEND);
                record.blendEnabled = true;
                int blendEqRGB = getGLEquationValue(getBlendEquationRGB());
                if (supportsSeparateEquations()) {
                    int blendEqAlpha = getGLEquationValue(getBlendEquationAlpha());
                    EXTBlendEquationSeparate.glBlendEquationSeparateEXT(
                            blendEqRGB, blendEqAlpha);
                    record.blendEqRGB = blendEqRGB;
                    record.blendEqAlpha = blendEqAlpha;
                } else if (supportsEq) {
                    ARBImaging.glBlendEquation(blendEqRGB);
                    record.blendEqRGB = blendEqRGB;
                }
            } else {
                GL11.glDisable(GL11.GL_BLEND);
                record.blendEnabled = false;
            }
        }
    }

    private void applyBlendColor(boolean enabled, BlendStateRecord record) {
        if (record.isValid()) {
            if (enabled) {
                boolean applyConstant = getDestinationFunctionRGB()
                        .usesConstantColor()
                        || getSourceFunctionRGB().usesConstantColor()
                        || (supportsConstantColor() && (getDestinationFunctionAlpha()
                                .usesConstantColor() || getSourceFunctionAlpha()
                                .usesConstantColor()));
                if (applyConstant && supportsConstantColor()) {
                    float r = 0, g = 0, b = 0, a = 0;
                    if (getConstantColor() != null) {
                        r = getConstantColor().r;
                        g = getConstantColor().g;
                        b = getConstantColor().b;
                        a = getConstantColor().a;
                    }
                    if (supportsConstantColor && (record.blendColor.r != r || record.blendColor.g != g
                            || record.blendColor.b != b
                            || record.blendColor.a != a)) {
                        ARBImaging.glBlendColor(r, g, b, a);
                        record.blendColor.set(r, g, b, a);
                    }
                }
            }
        } else {
            if (enabled) {
                boolean applyConstant = getDestinationFunctionRGB()
                        .usesConstantColor()
                        || getSourceFunctionRGB().usesConstantColor()
                        || (supportsConstantColor() && (getDestinationFunctionAlpha()
                                .usesConstantColor() || getSourceFunctionAlpha()
                                .usesConstantColor()));
                if (applyConstant && supportsConstantColor()) {
                    float r = 0, g = 0, b = 0, a = 0;
                    if (getConstantColor() != null) {
                        r = getConstantColor().r;
                        g = getConstantColor().g;
                        b = getConstantColor().b;
                        a = getConstantColor().a;
                    }
                    EXTBlendColor.glBlendColorEXT(r, g, b, a);
                    record.blendColor.set(r, g, b, a);
                }
            }
        }
    }

    private void applyBlendFunctions(boolean enabled, BlendStateRecord record) {
        if (record.isValid()) {
            if (enabled) {
                int glSrcRGB = getGLSrcValue(getSourceFunctionRGB());