ParticleRendererItem.h

/*
 * Copyright (C) 2014 Google Inc.
 *
 * 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.
 */

#ifndef PARTICLERENDERERITEM_H
#define PARTICLERENDERERITEM_H

#include <memory>
#include "Graphic.h"
#include "renderer/PointerDeclarations.h"
#include "renderer/RenderNode.h"

struct ParticleRendererItemFboDesc;
class b2ParticleSystem;
struct b2AABB;

struct ParticleShaderParams {
    QRectF updateRegion;
    float aspectRatio = 0.0f;
    float alpha = 0.0f;
    float zoomFactor = 0.0f;
    float highlightWidth = 0.0f;
    float highlightAlpha = 0.0f;
    QColor tintColor;
    QPointF shadowOffset;
    float shadowAlpha = 0.0f;
    QColor shadowColor;
    TexturePtr texture;
    TexturePtr specularTexture;
};

class ParticleRendererItem : public Graphic, private RenderableInterface {
    Q_OBJECT
public:
    constexpr static const int FBO_SIZE = 1024;
    constexpr static const int AUX_FBO_SIZE = 384;
    static const float PARTICLE_SCALE;

    virtual ~ParticleRendererItem();

protected:
    virtual void render(RenderNode* node) override;
    virtual void synchronizeForRendering(RenderList* renderList) override;

private:
    constexpr static const float NORMAL_ZOOM_FOV = 8.0f;
    constexpr static const int FBO_COUNT = 2;

    void synchronize();
    void renderFboContents();
    void renderParticleSystem(b2ParticleSystem* psystem, float scale, const QRectF& worldCullBounds,
            b2AABB* worldUpdateRegion);
    void createParticleShader();
    static void checkExtensions();

    float mZoomFactor = 0.0f;
    float mAspectRatio = 1.0f;
    bool mUpdateRegionEmpty = false;
    QRectF mUpdateRegion;
    int mFboIds[FBO_COUNT];
    int mFboTextureIds[FBO_COUNT];
    TexturePtr mFboTextures[FBO_COUNT];

    ShaderPtr mParticleShader;
    ShaderPtr mAuxFboSpecularShader;
    MeshInstancePtr mSquareFboToScreenMesh;
    TexturePtr mParticleTexture;
    RenderNode mRenderNode;
    ParticleShaderParams mRenderParams;

    static const ParticleRendererItemFboDesc FBO_DEFINITIONS[];
    // Whether or not the current GPU supports extensions allowing us to use the combined shader
    // rather than multiple stages for performance.
    static bool sParticleRendererUseCombinedShader;
};
Q_DECLARE_METATYPE(ParticleRendererItem*)

#endif // PARTICLERENDERERITEM_H