add 'random_sub_uv' particle setting

src/presets/ParticlesPreset.cpp

@@ -10,9 +10,11 @@ dv::value ParticlesPreset::serialize() const {
     root["max_distance"] = maxDistance;
     root["spawn_interval"] = spawnInterval;
     root["lifetime"] = lifetime;
+    root["lifetime_spread"] = lifetimeSpread;
     root["acceleration"] = dv::to_value(acceleration);
     root["explosion"] = dv::to_value(explosion);
     root["size"] = dv::to_value(size);
+    root["random_sub_uv"] = randomSubUV;
     return root;
 }
 
@@ -23,6 +25,8 @@ void ParticlesPreset::deserialize(const dv::value& src) {
     src.at("max_distance").get(maxDistance);
     src.at("spawn_interval").get(spawnInterval);
     src.at("lifetime").get(lifetime);
+    src.at("lifetime_spread").get(lifetimeSpread);
+    src.at("random_sub_uv").get(randomSubUV);
     if (src.has("acceleration")) {
         dv::get_vec(src["acceleration"], acceleration);
     }

src/presets/ParticlesPreset.hpp

@@ -15,6 +15,8 @@ struct ParticlesPreset : public Serializable {
     float spawnInterval = 0.1f;
     /// @brief Particle life time
     float lifetime = 5.0f;
+    /// @brief Life time spread divided by lifetime
+    float lifetimeSpread = 0.2f;
     /// @brief Initial velocity
     glm::vec3 velocity {};
     /// @brief Velocity acceleration
@@ -25,6 +27,8 @@ struct ParticlesPreset : public Serializable {
     glm::vec3 size {0.1f};
     /// @brief Texture name
     std::string texture = "";
+    /// @brief Size of random sub-uv region
+    float randomSubUV = 1.0f;
 
     dv::value serialize() const override;
     void deserialize(const dv::value& src) override;