add 'random_sub_uv' particle setting

res/content/base/scripts/world.lua

@@ -1,8 +1,9 @@
 function on_block_broken(id, x, y, z, playerid)
     particles.emit({x+0.5, y+0.5, z+0.5}, 100, {
-        lifetime=1.0,
+        lifetime=2.0,
         spawn_interval=0.0001,
         explosion={4, 4, 4},
-        texture="blocks:"..block.get_textures(id)[1]
+        texture="blocks:"..block.get_textures(id)[1],
+        random_sub_uv=0.1
     })
 end

src/graphics/render/Emitter.cpp

@@ -67,7 +67,16 @@ void Emitter::update(
         particle.emitter = this;
         particle.random = random.rand32();
         particle.position = position;
+        particle.lifetime *= 1.0f - preset.lifetimeSpread * random.randFloat();
         particle.velocity += glm::ballRand(1.0f) * preset.explosion;
+        if (preset.randomSubUV < 1.0f) {
+            particle.region.autoSub(
+                preset.randomSubUV,
+                preset.randomSubUV,
+                random.randFloat(),
+                random.randFloat()
+            );
+        }
         particles.push_back(std::move(particle));
         timer -= spawnInterval;
         if (count > 0) {

src/maths/UVRegion.hpp

@@ -22,4 +22,15 @@ struct UVRegion {
     inline float getHeight() const {
         return fabs(v2 - v1);
     }
+
+    void autoSub(float w, float h, float x, float y) {
+        x *= 1.0f - w;
+        y *= 1.0f - h;
+        float uvw = getWidth();
+        float uvh = getHeight();
+        u1 = u1 + uvw * x;
+        v1 = v1 + uvh * y;
+        u2 = u1 + uvw * w;
+        v2 = v1 + uvh * h;
+    }
 };

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;