shader_testing/src/tangerine.h

#pragma once

#include <SDL2/SDL.h>

#include "asset.h"
#include "entity.h"
#include "dumbLog.h"
#include "GLDebug.h"
#include "shader.h"
#include "types.h"
#include "util.h"


/*
* === TODO: ===
*  - full lighting model
*  - test complex entities
*  		- need a separate GLBufferToAttribMapping for each mesh on an entity
*  - fix debug load times (either by using cgltf, or hiding tinygltf.h)
*  - RenderGroups and Entities need to come into and out of existence during
*		gameplay. So, we need to extend MemoryArena to be a pool allocator
*		instead of an allocate only linear allocator
*  - add libTangerine namespace?
*  - merge back into libTangerine
*
* === TODONE: ===
*  - don't allocate Asset structure on asset arena
*    - store on RenderState as reference
*  - store asset arena to asset structure
*  - condense get_X_ByPath functions with assetLoad functions
*    - move to asset interface
*  - load diffuse texture automatically when loading a model
*  - move entity structure and functions to new file?
*  - load diffuse texture into OpenGL, and store GLTexture structure onto
*    GLContext
*	- need a cache algorithm starting in initEntity()
*		- check for GLTexture by path hash
*		- load texture into gl if not cached
*		- pass result GLTexture to loadGLMesh()
*  - update loadScene function with textured models, and test texture loading
*  - work on cleaner interface for initEntity and loadScene...
*  - add a LOGF macro for printf style logging
*		- replace instances of printf
*  - rename data structures to be in the new format, eg) UpperCaseStyleNames
*  - rename instances of 'model_xform' that refer to a mesh node to something
*  		like node_xform. model_xform should be reserved for the entity node
*  - move default shaders out of git-lfs
*/


struct SDLHandles
{
	SDL_Window* window;
	SDL_GLContext sdl_gl_ctx;
	SDL_DisplayMode display_mode;
};

// TODO: node/tree structure for entities
struct Node;

struct RenderGroup
{
	ShaderProgram* shader;
	u32 num_entities;
	u32 max_entities;
	Entity* entities;
	char* name;
};

struct GLClearColor
{
	GLfloat R;
	GLfloat G;
	GLfloat B;
	GLfloat A;
};

struct RenderState
{
	bool running;
	Transforms* xforms; // NOTE: would be part of camera in libTangerine
	SDLHandles* handles;
	GLContext* gl_ctx;
	Assets assets;

	MemoryArena* rg_arena;
	u32 num_render_groups;
	u32 max_render_groups;
	RenderGroup* render_groups;

	GLClearColor clear_col;
	// TODO: full lighting
#if 0
	u32 num_lights;
	u32 max_lights;
	PointLight* lights;
#endif
};


#define DEFAULT_MODEL_COUNT 256
#define DEFAULT_TEXTURE_COUNT 64
#define DEFAULT_SHADER_COUNT 64
#define DEFAULT_UBO_COUNT 32
#define DEFAULT_RENDER_GROUP_COUNT 256
RenderState* initRenderState(u32 max_models = DEFAULT_MODEL_COUNT,
	u32 max_textures = DEFAULT_TEXTURE_COUNT,
	u32 max_shaders = DEFAULT_SHADER_COUNT,
	u32 max_render_groups = DEFAULT_RENDER_GROUP_COUNT,
	u32 max_ubos = DEFAULT_UBO_COUNT);

void freeRenderState(RenderState*& rs);

#define DEFAULT_ENTITY_COUNT 256
void initRenderGroup(RenderGroup* rg,
		MemoryArena* arena,
		ShaderProgram* shader,
		u32 num_entities = DEFAULT_ENTITY_COUNT,
		const char* name = "");

void freeRenderGroup(RenderGroup* rg, MemoryArena* arena);

RenderGroup* getFreeRenderGroup(RenderState* rs);

Entity* getFreeEntity(RenderGroup* rg);

// NOTE: callback function signature to use with renDoRenderLoop()
typedef void (*frame_callback_fn) (RenderState*);

// NOTE: There are 2 callbacks to use here, cb_func_pre is called before
// 	the call to renRenderFrame(), cb_fun_post is called after
// NOTE: if you use cb_func_pre, you will have to use SDL_PollEvent() manually
// 	and at minimum set rs->running = false on SDL_QUIT event
void doRenderLoop(RenderState* rs,
	uint framerate = 60,
	frame_callback_fn cb_func_pre = nullptr,
	frame_callback_fn cb_func_post = nullptr);

void renderFrame(RenderState* rs, const GLClearColor& clear_col);


//  NOTE: automatic loading of default shaders

struct ShaderInit
{
	const char* name;
	const char* vert_path;
	const char* frag_path;
};

#define DEFAULT_SHADER_INIT { "default", \
	"../data/shader.vert", \
	"../data/shader.frag" }
#define DEBUG_SHADER_INIT { "debug", \
	"../data/debug.vert", \
	"../data/debug.frag", }
#define COLORED_VERT_SHADER_INIT { "colored_vertices", \
	"../data/colored_vertices.vert", \
	"../data/colored_vertices.frag", }
#define SHADER_INIT_COUNT 3
const ShaderInit SHADER_INIT_LIST[SHADER_INIT_COUNT]
{
	DEFAULT_SHADER_INIT,
	DEBUG_SHADER_INIT,
	COLORED_VERT_SHADER_INIT
};

bool loadDefaultShaders(RenderState* rs,
	u32 num_shaders = SHADER_INIT_COUNT,
	const ShaderInit shaders[] = SHADER_INIT_LIST);

// NOTE: only useful if the shader attribute names match the names in the
// 	default	shaders. If loading a custom shader, this may not work as expected,
// 	and you should use getVertexAttribByName instead
GLVertexAttrib* getVertexAttribByType(ShaderProgram* shader,
	MeshBufferType buf_type);