libTangerine/include/renderer.h

#pragma once

#if defined (_WIN32)
	#include <SDL.h>
#else
	#include <SDL2/SDL.h>
#endif
#include <GL/glew.h>
#include <glm/glm.hpp>

#include "asset.h"
#include "camera.h"
#include "entity.h"
#include "lights.h"
#include "util.h"
#include "shader_program.h"


// NOTE: array of entities rendered with the same shader program
struct render_group
{
	// TODO: also needs to be resizable
	entity* entities;
	uint entity_count;

	shader_wrapper shader;

	// TODO: does it makes sense to have the mesh_type stored on the
	// 	render_group? can then easily pass to roDraw() along with the entity
	// 	render_objects...
	// 	only the mesh object and render object really need to know about the
	// 	mesh_type...
	//
	//mesh_t mesh_type;
};

struct SDL_Handles
{
	SDL_Window *window;
	SDL_GLContext glContext;
	SDL_DisplayMode currentDisplayMode;
};

struct render_state
{
	glm::vec2 viewport_dims;
	camera cam;
	util_RGBA clear_col;
	SDL_Handles* handles;
	bool running;

	// TODO: this really needs to be a resizable array, or linked list, or
	// 	...gasp, std::vector
	render_group** render_groups;
	uint render_group_count;

	// WIP
	model_assets* models;
	memory_arena* arena;
	// FIXME: should be a hashmap for textures loaded from assets
	// 	ie) pallete textures
	util_image* textures;

	// TODO: hide shaders behind a better abstraction than 'shader_wrapper'
	default_shader_program* default_shader;
	simple_shader_program* simple_shader;

	light_group* lights;
};

#define DEFAULT_ASSET_SIZE 256
render_state*
renInit(const char* title = "Tangerine",
	glm::vec2 viewport_dims = glm::vec2(1280, 720),
	Uint32 SDL_init_flags = 0,
	size_t arena_size = DEFAULT_ARENA_SIZE,
	uint asset_size = DEFAULT_ASSET_SIZE);

void renShutdown(render_state* rs);

render_group*
renAllocateGroup(uint entity_count, shader_wrapper shader);

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

// 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
renDoRenderLoop(render_state* rs,
	uint framerate = 60,
	frame_callback_fn cb_func_pre = nullptr,
	frame_callback_fn cb_func_post = nullptr);

void renRenderFrame(render_state* rs);

bool
renAddLight(render_state* rs,
	glm::vec3 pos = glm::vec3(0, 0, 0),
	glm::vec3 color = glm::vec3(1, 1, 1),
	float intensity = 1.0);

glm::vec2
renGetWindowDims(render_state* rs);