add particles (WIP)

src/graphics/render/Emitter.cpp

@@ -0,0 +1,53 @@
+#include "Emitter.hpp"
+
+#include <glm/gtc/random.hpp>
+
+#include "graphics/core/Texture.hpp"
+
+Emitter::Emitter(
+    std::variant<glm::vec3, entityid_t> origin,
+    Particle prototype,
+    const Texture* texture,
+    float spawnInterval,
+    int count
+)
+    : origin(std::move(origin)),
+      prototype(std::move(prototype)),
+      texture(texture),
+      spawnInterval(spawnInterval),
+      count(count) {
+}
+
+const Texture* Emitter::getTexture() const {
+    return texture;
+}
+
+void Emitter::update(float delta, std::vector<Particle>& particles) {
+    if (count == 0) {
+        return;
+    }
+    glm::vec3 position {};
+    if (auto staticPos = std::get_if<glm::vec3>(&origin)) {
+        position = *staticPos;
+    } else {
+        // TODO: implement for entity origin
+    }
+    timer += delta;
+    while (count && timer > spawnInterval) {
+        // spawn particle
+        Particle particle = prototype;
+        particle.position = position;
+        particle.velocity += glm::ballRand(1.0f) * explosion;
+        particles.push_back(std::move(particle));
+        timer -= spawnInterval;
+        count--;
+    }
+}
+
+void Emitter::setExplosion(const glm::vec3& magnitude) {
+    explosion = magnitude;
+}
+
+bool Emitter::isDead() const {
+    return count == 0;
+}