shadowCatcher.h

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// SPDX-License-Identifier: Apache-2.0
// Copyright 2025-2026 Arnis Lektauers
//
//
// A script that creates a shadow-catching ground plane beneath the target entity.
// The plane uses a multiplicative-blend material with the LIT_SHADOW_CATCHER shader
// path, which outputs the accumulated shadow factor as a grayscale value. When blended
// multiplicatively with the framebuffer, lit areas remain unchanged while shadowed
// areas are darkened — giving the appearance of a shadow on the existing background.
//
#pragma once
 
#include <memory>
 
#include "script.h"
#include "scriptRegistry.h"
 
namespace visutwin::canvas
{
    class Entity;
    class StandardMaterial;

    class ShadowCatcher : public Script
    {
    public:
        SCRIPT_NAME("shadowCatcher")
 
        // --- Configuration (can be set before or after initialize) ---
 
        // Scale of the shadow-catching plane (default 20x20)
        float planeScale() const { return _planeScale; }
        void setPlaneScale(float value);
 
        // Vertical offset below the entity position (default 0)
        float yOffset() const { return _yOffset; }
        void setYOffset(float value);
 
        // Shadow intensity: 0 = no shadow, 1 = full shadow darkening (default 1.0)
        float intensity() const { return _intensity; }
        void setIntensity(float value) { _intensity = value; }
 
        void initialize() override;
 
    private:
        float _planeScale = 20.0f;
        float _yOffset = 0.0f;
        float _intensity = 1.0f;
 
        Entity* _planeEntity = nullptr;
        StandardMaterial* _material = nullptr;
    };
}
 
REGISTER_SCRIPT(visutwin::canvas::ShadowCatcher, "shadowCatcher")