add particles (WIP)

src/graphics/render/Emitter.hpp

@@ -0,0 +1,56 @@
+#pragma once
+
+#include <vector>
+#include <variant>
+#include <glm/glm.hpp>
+
+#include "typedefs.hpp"
+
+#include "maths/UVRegion.hpp"
+
+struct Particle {
+    glm::vec3 position;
+    glm::vec3 velocity;
+    float lifetime;
+    UVRegion region;
+};
+
+class Texture;
+
+class Emitter {
+    /// @brief Static position or entity
+    std::variant<glm::vec3, entityid_t> origin;
+    /// @brief Particle prototype
+    Particle prototype;
+    /// @brief Particle
+    const Texture* texture;
+    /// @brief Particles spawn interval
+    float spawnInterval;
+    /// @brief Number of particles should be spawned before emitter deactivation.
+    /// -1 is infinite
+    int count;
+    /// @brief Spawn timer used to determine number of particles 
+    /// to spawn on update. May be innacurate.
+    float timer = 0.0f;
+    /// @brief Random velocity magnitude applying to spawned particles
+    glm::vec3 explosion {1.0f};
+public:
+    Emitter(
+        std::variant<glm::vec3, entityid_t> origin,
+        Particle prototype,
+        const Texture* texture,
+        float spawnInterval,
+        int count
+    );
+
+    const Texture* getTexture() const;
+
+    /// @brief Update emitter and spawn particles
+    /// @param delta delta time
+    /// @param particles destination particles vector
+    void update(float delta, std::vector<Particle>& particles);    
+
+    void setExplosion(const glm::vec3& magnitude);
+
+    bool isDead() const;
+};