/*
* Copyright 2016 MovingBlocks
*
* 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.terasology.rendering.dag.stateChanges;
import static org.lwjgl.opengl.GL11.GL_BLEND;
import org.terasology.rendering.dag.RenderPipelineTask;
import org.terasology.rendering.dag.StateChange;
import org.terasology.rendering.dag.tasks.DisableStateParameterTask;
import org.terasology.rendering.dag.tasks.EnableStateParameterTask;
/**
* Instances of this class enable OpenGL's blending, i.e. to render transparent objects or to make
* a composite of different images.
*
* See also StateChange implementation SetBlendFunction to set the source and destination factors
* used by the blending process.
*/
public final class EnableBlending extends SetStateParameter {
private static final int PARAMETER = GL_BLEND;
private static final String PARAMETER_NAME = "GL_BLEND";
private static StateChange defaultInstance = new EnableBlending(false);
private static RenderPipelineTask enablingTask;
private static RenderPipelineTask disablingTask;
/**
* Constructs an instance of this StateChange. This is can be used in a node's initialise() method in
* the form:
*
* addDesiredStateChange(new EnableBlending());
*
* This trigger the inclusion of an EnableStateParameterTask instance and a DisableStateParameterTask instance
* in the rendering task list, each instance enabling/disabling respectively the GL_BLEND mode. The
* two task instance frame the execution of a node's process() method unless they are deemed redundant,
* i.e. because the upstream or downstream node also enables blending.
*
* See also StateChange implementation SetBlendFunction to set the source and destination factors
* used by the blending process.
*/
public EnableBlending() {
this(true);
}
private EnableBlending(boolean enabled) {
super(GL_BLEND, enabled);
disablingTask = new DisableStateParameterTask(PARAMETER, PARAMETER_NAME);
enablingTask = new EnableStateParameterTask(PARAMETER, PARAMETER_NAME);
}
@Override
public StateChange getDefaultInstance() {
return defaultInstance;
}
@Override
protected RenderPipelineTask getDisablingTask() {
return disablingTask;
}
@Override
protected RenderPipelineTask getEnablingTask() {
return enablingTask;
}
@Override
public boolean isTheDefaultInstance() {
return this.equals(defaultInstance);
}
}