COP2/COP2_SampleFilter.h

/*
 * Copyright (c) 2025
 *      Side Effects Software Inc.  All rights reserved.
 *
 * Redistribution and use of Houdini Development Kit samples in source and
 * binary forms, with or without modification, are permitted provided that the
 * following conditions are met:
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 *    this list of conditions and the following disclaimer.
 * 2. The name of Side Effects Software may not be used to endorse or
 *    promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY SIDE EFFECTS SOFTWARE `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 SIDE EFFECTS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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 *----------------------------------------------------------------------------
 * This operator does a simple pixel modification on its input.
 */
#ifndef _COP2_SAMPLEFILTER_H_
#define _COP2_SAMPLEFILTER_H_

#include <COP2/COP2_Context.h>
#include <COP2/COP2_MaskOp.h>

namespace HDK_Sample {

/// @brief Simple example of a kernel filter.

/// This is an HDK example of a 3x3 kernel filter which uses template classes
/// to abstract the operation for various data formats. It also demonstrates
/// how to deal with fetching input areas larger than a tile, and how to
/// enlarging the canvas for the COP.
class COP2_SampleFilter : public COP2_MaskOp
{
public:
    /// All nodes are instantiated via a myConstructor method.
    static OP_Node              *myConstructor(OP_Network*, const char *,
                                               OP_Operator *);
    
    /// @{
    /// Parameters, local variables and input labals.
    static OP_TemplatePair       myTemplatePair;
    static OP_VariablePair       myVariablePair;
    static PRM_Template          myTemplateList[];
    static CH_LocalVariable      myVariableList[];
    static const char           *myInputLabels[];
    /// @}
    
    /// Given an area of the image to cook, indicate which parts of the input's
    /// image are required
    void                 getInputDependenciesForOutputArea(
                            COP2_CookAreaInfo &output_area,
                            const COP2_CookAreaList &input_areas,
                            COP2_CookAreaList &needed_areas) override;
protected:
    /// This operation expands the canvas bounds by 1 pixel in all directions.
    /// computeImageBounds() announces this to the COP engine.
    void                 computeImageBounds(COP2_Context &context) override;

    /// Returns a new context instance with the parameters for the filter in
    /// it, to be used by the many threads on the tiles.
    COP2_ContextData    *newContextData(const TIL_Plane *p,
                                                int array_index,
                                                float t,
                                                int xres, int yres,
                                                int thread,
                                                int max_threads) override;

    /// COP2_MaskOp defines lots of nice mask blending operations in
    /// cookMyTile(), and defines doCookMyTile for us to override instead.
    /// This is where the actual image operation is performed.
    OP_ERROR            doCookMyTile(COP2_Context &context,
                                     TIL_TileList *tilelist) override;

    /// Returns a description of the operation for the node info popup.
    const char          *getOperationInfo() override;
    
                ~COP2_SampleFilter() override;

private:
                COP2_SampleFilter(OP_Network *parent, const char *name,
                             OP_Operator *entry);

    /// @{
    /// Parameter evaluation method; can call evalFloat directly as well.
    fpreal      LEFT(fpreal t)
                { return evalFloat("left",0,t); }
    
    fpreal      RIGHT(fpreal t)
                { return evalFloat("right",0,t); }
    
    fpreal      TOP(fpreal t)
                { return evalFloat("top",0,t); }
    
    fpreal      BOTTOM(fpreal t)
                { return evalFloat("bottom",0,t); }
    /// @}
};

/// Storage class for our parameters and the kernel
class cop2_SampleFilterContext : public COP2_ContextData
{
public:
                 cop2_SampleFilterContext()
                     : myLeft(0.0f), myRight(0.0f), myTop(0.0f), myBottom(0.0f),
                       myKernel(NULL)
                 {}
    
                ~cop2_SampleFilterContext() override { delete [] myKernel; }

    /// When true, this context data object is recreated for each plane.
    bool        createPerPlane() const override { return false; }

    /// When true, this context data object is recreated for each resolution
    /// cooked.
    bool        createPerRes() const override   { return true; }

    /// When true, this context data object is recreated for each frame. In most
    /// cases, this returns true since parameters can be animated.
    bool        createPerTime() const override  { return true; }

    /// When true, each thread gets its own version of a context data. This is
    /// useful if the context data contains allocated memory to be used for 
    /// intermediate steps.
    bool        createPerThread() const override{ return false; }

    /// @{
    /// Cached Parameters
    float       myLeft;
    float       myRight;
    float       myTop;
    float       myBottom;
    /// @}
    
    /// Kernel filter derived from parameters
    float      *myKernel;
};

} // End HDK_Sample namespace

#endif