spk_view_region.hpp

#pragma once
 
#include <cstddef>
 
#include "structure/container/spk_flags.hpp"
#include "structure/graphics/spk_color.hpp"
#include "structure/graphics/spk_extend_2d.hpp"
#include "structure/math/spk_matrix.hpp"
 
namespace spk
{
    namespace OpenGL
    {
        class ViewRegion
        {
        public:
            enum class ClearMode
            {
                Color,
                Depth,
                Stencil
            };

            using ClearMask = spk::Flags<ClearMode>;
            static const ClearMask defaultClearMask;
 
        private:
            spk::Extend2D _viewport;
            spk::Extend2D _scissor;
 
            // Global transforms and configuration
            inline static const spk::OpenGL::ViewRegion *_activeViewRegion = nullptr;
            inline static spk::Matrix4x4 _screenToOpenGLMatrix = spk::Matrix4x4::identity();
            inline static spk::Matrix4x4 _openGLToScreenMatrix = spk::Matrix4x4::identity();
            inline static size_t _maxLayer = 1;
 
            // New: window size in pixels (top-left origin)
            inline static spk::Extend2D _windowSize{}; // {x=0,y=0,width=0,height=0} by default
 
            static void _applyViewport(const spk::Extend2D &p_extend);
            static void _applyScissor(const spk::Extend2D &p_extend);
            static spk::Matrix4x4 _computeScreenToOpenGLMatrix(const spk::Extend2D &p_viewport, size_t p_maxLayer);
            static spk::Matrix4x4 _computeOpenGLToScreenMatrix(const spk::Matrix4x4 &p_screenToOpenGLMatrix);
 
        public:
            ViewRegion() = default;

            void setViewport(const spk::Extend2D &p_extend) noexcept;
            void setScissor(const spk::Extend2D &p_extend) noexcept;

            const spk::Extend2D &viewport() const noexcept;
            const spk::Extend2D &scissor() const noexcept;

            static size_t maxLayer() noexcept;

            static void setMaxLayer(size_t p_maxLayer) noexcept;

            static void setWindowSize(const spk::Extend2D &p_windowSize) noexcept;

            static const spk::Extend2D &windowSize() noexcept;

            static const spk::OpenGL::ViewRegion *activeViewRegion();

            void apply() const;
            static void clear(const Color &p_backgroundColor, const ClearMask &p_clearMask = defaultClearMask);

            static spk::Vector3 convertScreenToOpenGL(const spk::Vector2Int &p_screenPosition, float p_layer = 0.0f) noexcept;

            static spk::Vector2Int convertOpenGLToScreen(const spk::Vector2 &p_openGLPosition, float p_layer = 0.0f) noexcept;
        };
    }
}