Viewport.hpp

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#ifndef DONUT_GRAPHICS_VIEWPORT_HPP
#define DONUT_GRAPHICS_VIEWPORT_HPP
 
#include <donut/math.hpp>
 
#include <utility> // std::pair
 
namespace donut::graphics {
 
struct Viewport {
    [[nodiscard]] static constexpr std::pair<Viewport, int> createIntegerScaled(ivec2 framebufferSize, ivec2 renderResolution) noexcept {
        Viewport result{.position{}, .size = renderResolution};
        int scale = 1;
        while (true) {
            const ivec2 nextViewportSize = renderResolution * (scale + 1);
            if (nextViewportSize.x > framebufferSize.x || nextViewportSize.y > framebufferSize.y) {
                break;
            }
            result.size = nextViewportSize;
            ++scale;
        }
        result.position = (framebufferSize - result.size) / 2;
        return {result, scale};
    }
 
    ivec2 position;
 
    ivec2 size;
};
 
} // namespace donut::graphics
 
#endif