ADD: game API docs
This commit is contained in:
166
docs/GameAPI.md
Normal file
166
docs/GameAPI.md
Normal file
@@ -0,0 +1,166 @@
|
||||
## Game‑Facing API Overview
|
||||
|
||||
This document summarizes the main engine APIs that are directly useful when building a game (spawn actors, control lights/animations, and interact via picking).
|
||||
|
||||
For details on the underlying systems, see also:
|
||||
|
||||
- `docs/Scene.md` – cameras, draw context, instances, picking.
|
||||
- `docs/EngineContext.md` – access to managers and per‑frame state.
|
||||
- `docs/RenderGraph.md` – render‑graph API for custom passes.
|
||||
|
||||
---
|
||||
|
||||
## VulkanEngine Helpers
|
||||
|
||||
Header: `src/core/engine.h`
|
||||
|
||||
- Lifecycle
|
||||
- `void init()` – initialize SDL, device, managers, scene, render graph.
|
||||
- `void run()` – main loop: handles events, updates scene, builds Render Graph, submits frames.
|
||||
- `void cleanup()` – destroy managers and GPU resources.
|
||||
|
||||
- GLTF spawn helper
|
||||
- `bool addGLTFInstance(const std::string &instanceName, const std::string &modelRelativePath, const glm::mat4 &transform = glm::mat4(1.f));`
|
||||
- Loads a glTF from `assets/models/...` (via `AssetManager`) and registers it as a runtime scene instance.
|
||||
- `instanceName` becomes the logical name used by `SceneManager` (e.g. for picking and animation control).
|
||||
|
||||
- Picking access
|
||||
- `struct PickInfo` (nested in `VulkanEngine`)
|
||||
- `MeshAsset *mesh`, `LoadedGLTF *scene`, `Node *node`
|
||||
- `RenderObject::OwnerType ownerType` (e.g. `StaticGLTF`, `GLTFInstance`, `MeshInstance`)
|
||||
- `std::string ownerName`
|
||||
- `glm::vec3 worldPos`
|
||||
- `glm::mat4 worldTransform`
|
||||
- `uint32_t indexCount`, `firstIndex`, `surfaceIndex`
|
||||
- `bool valid`
|
||||
- `const PickInfo &get_last_pick() const`
|
||||
- Returns the last click selection result.
|
||||
- Filled by the engine from either CPU ray picking or ID‑buffer picking depending on `_useIdBufferPicking`.
|
||||
- Typical usage:
|
||||
- On mouse‑up in your game layer, read `engine->get_last_pick()` and, if `valid`, use `ownerName`/`worldPos` to drive selection logic.
|
||||
|
||||
> Note: hover picks and drag selections are also available as internal fields on `VulkanEngine` (`_hoverPick`, `_dragSelection`) and are documented in `docs/Scene.md`. You can expose additional getters if you want to rely on them from game code.
|
||||
|
||||
---
|
||||
|
||||
## Scene & Instances (Actors, Lights, Animations)
|
||||
|
||||
Header: `src/scene/vk_scene.h`
|
||||
Docs: `docs/Scene.md`
|
||||
|
||||
### Dynamic Mesh/GLTF Instances
|
||||
|
||||
- Mesh instances
|
||||
- `void addMeshInstance(const std::string &name, std::shared_ptr<MeshAsset> mesh, const glm::mat4 &transform = glm::mat4(1.f), std::optional<BoundsType> boundsType = {});`
|
||||
- `bool getMeshInstanceTransform(const std::string &name, glm::mat4 &outTransform);`
|
||||
- `bool setMeshInstanceTransform(const std::string &name, const glm::mat4 &transform);`
|
||||
- `bool removeMeshInstance(const std::string &name);`
|
||||
- `void clearMeshInstances();`
|
||||
- Typical usage:
|
||||
- Spawn primitives or dynamic meshes at runtime (e.g. projectiles, props).
|
||||
- Use `setMeshInstanceTransform` every frame to move them based on game logic.
|
||||
|
||||
- GLTF instances (actors)
|
||||
- `void addGLTFInstance(const std::string &name, std::shared_ptr<LoadedGLTF> scene, const glm::mat4 &transform = glm::mat4(1.f));`
|
||||
- `bool getGLTFInstanceTransform(const std::string &name, glm::mat4 &outTransform);`
|
||||
- `bool setGLTFInstanceTransform(const std::string &name, const glm::mat4 &transform);`
|
||||
- `bool removeGLTFInstance(const std::string &name);`
|
||||
- `void clearGLTFInstances();`
|
||||
- Usage pattern:
|
||||
- Treat each GLTF instance as an “actor” with a name; use transforms to place characters, doors, props, etc.
|
||||
|
||||
### Animations (GLTF)
|
||||
|
||||
- Scene‑level
|
||||
- `bool setSceneAnimation(const std::string &sceneName, int animationIndex, bool resetTime = true);`
|
||||
- `bool setSceneAnimation(const std::string &sceneName, const std::string &animationName, bool resetTime = true);`
|
||||
- `bool setSceneAnimationLoop(const std::string &sceneName, bool loop);`
|
||||
- Instance‑level
|
||||
- `bool setGLTFInstanceAnimation(const std::string &instanceName, int animationIndex, bool resetTime = true);`
|
||||
- `bool setGLTFInstanceAnimation(const std::string &instanceName, const std::string &animationName, bool resetTime = true);`
|
||||
- `bool setGLTFInstanceAnimationLoop(const std::string &instanceName, bool loop);`
|
||||
- Notes:
|
||||
- All functions return `bool` indicating whether the named scene/instance exists.
|
||||
- `SceneManager::update_scene()` advances active animations each frame using engine delta time.
|
||||
|
||||
### Point Lights
|
||||
|
||||
- Struct:
|
||||
- `struct PointLight { glm::vec3 position; float radius; glm::vec3 color; float intensity; };`
|
||||
- API:
|
||||
- `void addPointLight(const PointLight &light);`
|
||||
- `void clearPointLights();`
|
||||
- `size_t getPointLightCount() const;`
|
||||
- `bool getPointLight(size_t index, PointLight &outLight) const;`
|
||||
- `bool setPointLight(size_t index, const PointLight &light);`
|
||||
- `bool removePointLight(size_t index);`
|
||||
- Typical usage:
|
||||
- On level load, add all static lights.
|
||||
- At runtime, animate or toggle lights based on gameplay events (e.g. explosions, flickering lamps).
|
||||
|
||||
---
|
||||
|
||||
## Picking & Selection (Interaction)
|
||||
|
||||
Picking lives in `SceneManager` and is wired into `VulkanEngine`’s frame loop.
|
||||
|
||||
Header: `src/scene/vk_scene.h`
|
||||
Implementation: `src/scene/vk_scene_picking.cpp`
|
||||
|
||||
### Single‑Object Ray Picking
|
||||
|
||||
- `bool pick(const glm::vec2 &mousePosPixels, RenderObject &outObject, glm::vec3 &outWorldPos);`
|
||||
- Input:
|
||||
- `mousePosPixels` – window coordinates (SDL style), origin at top‑left.
|
||||
- Output on success:
|
||||
- `outObject` – closest `RenderObject` hit by the camera ray.
|
||||
- `outWorldPos` – precise world‑space hit position (uses mesh BVH when available).
|
||||
- Returns:
|
||||
- `true` if any object was hit, otherwise `false`.
|
||||
|
||||
### ID‑Buffer Picking
|
||||
|
||||
- `bool resolveObjectID(uint32_t id, RenderObject &outObject) const;`
|
||||
- Takes an ID read back from the ID buffer and resolves it to the corresponding `RenderObject` in the latest `DrawContext`.
|
||||
- Used by the engine when `_useIdBufferPicking` is enabled to implement asynchronous picking.
|
||||
|
||||
### Rectangle Selection (Drag Box)
|
||||
|
||||
- `void selectRect(const glm::vec2 &p0, const glm::vec2 &p1, std::vector<RenderObject> &outObjects) const;`
|
||||
- Inputs:
|
||||
- `p0`, `p1` – opposite corners of a window‑space rectangle (top‑left origin).
|
||||
- Output:
|
||||
- `outObjects` – appended with all `RenderObject`s whose projected bounds intersect the rectangle.
|
||||
- Internals:
|
||||
- Uses `sceneData.viewproj` and an NDC‑space bounds test to determine overlap.
|
||||
|
||||
### Typical Game Usage
|
||||
|
||||
- Hover tooltips:
|
||||
- Track mouse position in window coordinates.
|
||||
- Use `SceneManager::pick` directly, or read `VulkanEngine::get_last_pick()` and/or `_hoverPick` as documented in `Scene.md`.
|
||||
- Object selection / interaction:
|
||||
- On mouse click release, inspect `engine->get_last_pick()`:
|
||||
- If `valid`, dispatch interaction based on `ownerType` / `ownerName` (e.g. select unit, open door).
|
||||
- Multi‑select:
|
||||
- When implementing drag selection, call `SceneManager::selectRect` with the drag rectangle to get all hits, or reuse the engine’s `_dragSelection` mechanism.
|
||||
|
||||
---
|
||||
|
||||
## ImGui / ImGuizmo Editor Utilities
|
||||
|
||||
File: `src/core/engine_ui.cpp`
|
||||
|
||||
These are primarily debug/editor features but can be kept in a game build to provide in‑game tools.
|
||||
|
||||
- Main entry:
|
||||
- `void vk_engine_draw_debug_ui(VulkanEngine *eng);`
|
||||
- Called once per frame by the engine to build the “Debug” window tabs.
|
||||
- Useful tools for games:
|
||||
- Scene tab:
|
||||
- Spawn glTF instances at runtime using `VulkanEngine::addGLTFInstance(...)`.
|
||||
- Spawn primitive mesh instances (cube/sphere) using `SceneManager::addMeshInstance(...)`.
|
||||
- Point‑light editor UI built on `SceneManager` light APIs.
|
||||
- Object gizmo (ImGuizmo):
|
||||
- Uses last pick / hover pick as the current target and manipulates transforms via `setMeshInstanceTransform` / `setGLTFInstanceTransform`.
|
||||
|
||||
Reference in New Issue
Block a user