ADD: Particle system

src/render/passes/particles.h

@@ -0,0 +1,105 @@
+#pragma once
+
+#include "core/world.h"
+#include "render/graph/types.h"
+#include "render/renderpass.h"
+
+#include <glm/glm.hpp>
+#include <vector>
+
+class RenderGraph;
+
+class ParticlePass : public IRenderPass
+{
+public:
+    static constexpr uint32_t k_max_particles = 128u * 1024u;
+
+    enum class BlendMode : uint32_t
+    {
+        Additive = 0,
+        Alpha = 1,
+    };
+
+    struct Params
+    {
+        glm::vec3 emitter_pos_local{0.0f, 0.0f, 0.0f};
+        float spawn_radius{0.1f};
+
+        glm::vec3 emitter_dir_local{0.0f, 1.0f, 0.0f};
+        float cone_angle_degrees{20.0f};
+
+        float min_speed{2.0f};
+        float max_speed{8.0f};
+
+        float min_life{0.5f};
+        float max_life{1.5f};
+
+        float min_size{0.05f};
+        float max_size{0.15f};
+
+        float drag{1.0f};
+        float gravity{0.0f}; // positive pulls down -Y in local space
+
+        glm::vec4 color{1.0f, 0.5f, 0.1f, 1.0f};
+    };
+
+    struct System
+    {
+        uint32_t id{0};
+        uint32_t base{0};
+        uint32_t count{0};
+        bool enabled{true};
+        bool reset{true};
+        BlendMode blend{BlendMode::Additive};
+        Params params{};
+    };
+
+    void init(EngineContext *context) override;
+    void cleanup() override;
+    void execute(VkCommandBuffer cmd) override;
+    const char *getName() const override { return "Particles"; }
+
+    void register_graph(RenderGraph *graph, RGImageHandle hdrTarget, RGImageHandle depthHandle);
+
+    uint32_t create_system(uint32_t count);
+    bool destroy_system(uint32_t id);
+    bool resize_system(uint32_t id, uint32_t new_count);
+
+    std::vector<System> &systems() { return _systems; }
+    const std::vector<System> &systems() const { return _systems; }
+
+    uint32_t allocated_particles() const;
+    uint32_t free_particles() const;
+
+private:
+    struct FreeRange
+    {
+        uint32_t base{0};
+        uint32_t count{0};
+    };
+
+    bool allocate_range(uint32_t count, uint32_t &out_base);
+    void free_range(uint32_t base, uint32_t count);
+    void merge_free_ranges();
+
+    System *find_system(uint32_t id);
+
+    EngineContext *_context = nullptr;
+
+    AllocatedBuffer _particle_pool{};
+    VkDeviceSize _particle_pool_size = 0;
+
+    VkDescriptorSetLayout _particle_set_layout = VK_NULL_HANDLE;
+
+    uint32_t _next_system_id = 1;
+    std::vector<System> _systems;
+    std::vector<FreeRange> _free_ranges;
+
+    float _time_sec = 0.0f;
+    float _dt_sec = 0.0f;
+    glm::vec3 _origin_delta_local{0.0f};
+
+    WorldVec3 _prev_origin_world{0.0, 0.0, 0.0};
+    bool _has_prev_origin = false;
+};
+