abstract_viewer_drawer.h

/*****************************************************************************
 * VCLib                                                                     *
 * Visual Computing Library                                                  *
 *                                                                           *
 * Copyright(C) 2021-2025                                                    *
 * Visual Computing Lab                                                      *
 * ISTI - Italian National Research Council                                  *
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 * All rights reserved.                                                      *
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 * This program is free software; you can redistribute it and/or modify      *
 * it under the terms of the Mozilla Public License Version 2.0 as published *
 * by the Mozilla Foundation; either version 2 of the License, or            *
 * (at your option) any later version.                                       *
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 * This program is distributed in the hope that it will be useful,           *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the              *
 * Mozilla Public License Version 2.0                                        *
 * (https://www.mozilla.org/en-US/MPL/2.0/) for more details.                *
 ****************************************************************************/
 
#ifndef VCL_RENDER_DRAWERS_ABSTRACT_VIEWER_DRAWER_H
#define VCL_RENDER_DRAWERS_ABSTRACT_VIEWER_DRAWER_H
 
#include <vclib/render/concepts/view_projection_event_drawer.h>
#include <vclib/render/drawable/drawable_object_vector.h>
#include <vclib/render/drawers/event_drawer.h>
#include <vclib/render/read_buffer_types.h>
#include <vclib/space/core/color.h>
 
#include <memory>
 
namespace vcl {
 
template<typename ViewProjEventDrawer>
class AbstractViewerDrawer : public ViewProjEventDrawer
{
    using Base = ViewProjEventDrawer;
    using DRA  = ViewProjEventDrawer::DRA;
 
    bool mReadRequested = false;
 
    // the default id for the viewer drawer is 0
    uint mId = 0;
 
protected:
    // the list of drawable objects
    // it could be owned by the viewer, or it could be shared with other
    // objects (e.g. the window that contains the viewer along with other
    // widgets)
    std::shared_ptr<DrawableObjectVector> mDrawList =
        std::make_shared<DrawableObjectVector>();
 
    // the drawer id
    uint& id() { return mId; }
 
public:
    AbstractViewerDrawer(uint width = 1024, uint height = 768) :
            Base(width, height)
    {
        static_assert(
            ViewProjectionEventDrawerConcept<Base>,
            "AbstractViewerDrawer requires a ViewProjectionEventDrawer as a "
            "base class");
    }
 
    ~AbstractViewerDrawer() = default;
 
    const DrawableObjectVector& drawableObjectVector() const
    {
        return *mDrawList;
    }
 
    void setDrawableObjectVector(const std::shared_ptr<DrawableObjectVector>& v)
    {
        mDrawList = v;
 
        for (auto obj : *mDrawList) {
            obj->init();
        }
        fitScene();
    }
 
    uint pushDrawableObject(const DrawableObject& obj)
    {
        mDrawList->pushBack(obj);
        mDrawList->back()->init();
        return mDrawList->size() - 1;
    }
 
    uint pushDrawableObject(DrawableObject&& obj)
    {
        mDrawList->pushBack(std::move(obj));
        mDrawList->back()->init();
        return mDrawList->size() - 1;
    }
 
    void fitScene()
    {
        Point3f sceneCenter;
        float   sceneRadius = 1;
 
        Box3d bb = mDrawList->boundingBox();
 
        if (!bb.isNull()) {
            sceneCenter = bb.center().cast<float>();
            sceneRadius = bb.diagonal();
        }
 
        Base::fitScene(sceneCenter, sceneRadius);
    }
 
    // events
    void onInit(uint) override
    {
        DRA::DRW::setCanvasDefaultClearColor(derived(), Color::DarkGray);
    }
 
    void onKeyPress(Key::Enum key, const KeyModifiers& modifiers) override
    {
        Base::onKeyPress(key, modifiers);
 
        switch (key) {
        case Key::S:
            if (modifiers[KeyModifier::CONTROL])
                DRA::DRW::screenshot(derived(), "viewer_screenshot.png");
            break;
 
        default: break;
        }
    }
 
protected:
    void readDepthRequest(double x, double y, bool homogeneousNDC = true)
    {
        using ReadData   = ReadBufferTypes::ReadData;
        using FloatData  = ReadBufferTypes::FloatData;
        using MatrixType = Base::MatrixType;
 
        if (mReadRequested)
            return;
 
        // get point
        const Point2d p(x, y);
 
        // create the callback
        const auto proj = Base::projectionMatrix();
        const auto view = Base::viewMatrix();
        // viewport
        auto size = DRA::DRW::canvasSize(derived());
 
        const Point4f vp = {.0f, .0f, float(size.x()), float(size.y())};
 
        auto callback = [=, this](const ReadData& dt) {
            const auto& data = std::get<FloatData>(dt);
            assert(data.size() == 1);
            const float depth = data[0];
 
            mReadRequested = false;
 
            // if the depth is 1.0, the point is not in the scene
            if (depth == 1.0f) {
                return;
            }
 
            // unproject the point
            const Point3f p2d(p.x(), vp[3] - p.y(), depth);
            auto          unproj =
                unproject(p2d, MatrixType(proj * view), vp, homogeneousNDC);
 
            this->focus(unproj);
            derived()->update();
        };
 
        mReadRequested =
            DRA::DRW::readDepth(derived(), Point2i(p.x(), p.y()), callback);
        if (mReadRequested)
            derived()->update();
    }
 
    void readIdRequest(double x, double y, std::function<void(uint)> idCallback)
    {
        using ReadData = ReadBufferTypes::ReadData;
 
        if (mReadRequested)
            return;
 
        // get point
        const Point2d p(x, y);
 
        // create the callback
        auto callback = [=, this](const ReadData& dt) {
            const auto& data = std::get<ReadBufferTypes::ByteData>(dt);
            assert(data.size() == 4);
            // TODO: check how to do this properly
            const uint id = *(uint32_t*) &data[0];
 
            mReadRequested = false;
 
            idCallback(id);
            derived()->update();
        };
 
        mReadRequested =
            DRA::DRW::readId(derived(), Point2i(p.x(), p.y()), callback);
        if (mReadRequested)
            derived()->update();
    }
 
private:
    auto* derived() { return static_cast<DRA*>(this); }
 
    const auto* derived() const { return static_cast<const DRA*>(this); }
};
 
} // namespace vcl
 
#endif // VCL_RENDER_DRAWERS_ABSTRACT_VIEWER_DRAWER_H