VegetationField.h

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#pragma once
#include "common/Export.h"
 
#include <array>
#include <cstdint>
#include <glm/vec3.hpp>
#include <glm/vec4.hpp>
#include <span>
#include <vector>
#include "common/Result.h"
#include "common/Value.h"
 
namespace eve::graphics {
 
enum class VegetationChannel : uint8_t { Color, Extras, Motion, Vertex };
enum class VegetationBlend : uint8_t { Replace, Add, Multiply, Minimum, Maximum };
enum class VegetationShape : uint8_t { Ellipsoid, Box };
 
struct VegetationMask {
    uint32_t               width = 0, height = 0;
    std::vector<glm::vec4> pixels;
};
 
struct VegetationElement {
    VegetationChannel        channel = VegetationChannel::Color;
    VegetationBlend          blend   = VegetationBlend::Replace;
    VegetationShape          shape   = VegetationShape::Ellipsoid;
    glm::vec3                center{0.f}, extents{1.f};
    float                    yaw = 0.f, opacity = 1.f, edgeFade = 0.25f;
    uint16_t                 layers   = 1;
    int                      priority = 0;
    glm::vec4                value{1.f};
    bool                     seasonal = false;
    std::array<glm::vec4, 4> seasons{glm::vec4(1.f), glm::vec4(1.f), glm::vec4(1.f), glm::vec4(1.f)};
    VegetationMask           mask;
};
 
struct VegetationGlobals {
    glm::vec4 color{1.f, 1.f, 1.f, 0.f};
    glm::vec4 extras{1.f, 0.f, 0.f, 1.f};
    glm::vec4 motion{1.f, 0.f, 0.5f, 0.f};
    glm::vec4 vertex{0.f, 0.f, 0.f, 1.f};
    float     season = 2.f;
};
 
struct VegetationSample {
    glm::vec4 color, extras, motion, vertex;
};
 
struct VegetationAtlas {
    uint32_t                              width = 0, height = 0;
    glm::vec3                             center{0.f}, extent{1.f};
    std::array<std::vector<glm::vec4>, 4> channels;
};
 
struct VegetationChannelAtlas {
    uint32_t               width = 0, height = 0;
    glm::vec3              center{0.f}, extent{1.f};
    std::vector<glm::vec4> pixels;
};
 
class EVENGINE_API_BACKENDS VegetationField {
public:
    VegetationGlobals globalValues() const { return globals_; }
    uint64_t revision() const { return revision_; }
    [[nodiscard]] Result<std::vector<VegetationElement>> snapshotElements() const;
    [[nodiscard]] Result<void> restore(const Value& document);
    [[nodiscard]] Result<Value> snapshot() const;
    [[nodiscard]] Result<void> replace(const VegetationGlobals& globals, std::span<const VegetationElement> elements);
    [[nodiscard]] Result<VegetationSample> sample(glm::vec3 position, std::array<uint8_t, 4> layers = {}) const;
    [[nodiscard]] Result<VegetationAtlas> bake(glm::vec3 center, glm::vec3 extent, uint32_t width, uint32_t height,
                                               std::array<uint8_t, 4> layers = {}, bool snapToTexel = true) const;
 
private:
    VegetationSample               evaluate(glm::vec3 position, std::array<uint8_t, 4> layers) const;
    VegetationGlobals              globals_;
    std::vector<VegetationElement> elements_;
    uint64_t                       revision_ = 0;
};
}  // namespace eve::graphics