karl2d/karl2d.odin

package karl2d

import "base:runtime"
import "core:mem"
import "core:log"
import "core:math"
import "core:math/linalg"
import "core:slice"
import "core:strings"
import "core:reflect"

import "core:image"
import "core:image/bmp"
import "core:image/png"
import "core:image/tga"

import hm "handle_map"

//-----------------------------------------------//
// SETUP, WINDOW MANAGEMENT AND FRAME MANAGEMENT //
//-----------------------------------------------//

/* Opens a window and initializes some internal state. The internal state will use `allocator` for
all dynamically allocated memory. The return value can be ignored unless you need to later call
`set_internal_state`. */
init :: proc(window_width: int, window_height: int, window_title: string,
             allocator := context.allocator, loc := #caller_location) -> ^State {
	assert(s == nil, "Don't call 'init' twice.")

	s = new(State, allocator, loc)
	s.allocator = allocator
	s.custom_context = context

	s.width = window_width
	s.height = window_height

	s.win = WINDOW_INTERFACE_WIN32
	win = s.win

	window_state_alloc_error: runtime.Allocator_Error
	s.window_state, window_state_alloc_error = mem.alloc(win.state_size())
	log.assertf(window_state_alloc_error == nil, "Failed allocating memory for window state: %v", window_state_alloc_error)

	win.init(s.window_state, window_width, window_height, window_title, allocator)
	s.window = win.window_handle()

	s.rb = BACKEND_D3D11
	rb = s.rb
	rb_alloc_error: runtime.Allocator_Error
	s.rb_state, rb_alloc_error = mem.alloc(rb.state_size())
	log.assertf(rb_alloc_error == nil, "Failed allocating memory for rendering backend: %v", rb_alloc_error)
	s.proj_matrix = make_default_projection(window_width, window_height)
	s.view_matrix = 1
	rb.init(s.rb_state, s.window, window_width, window_height, allocator)
	s.vertex_buffer_cpu = make([]u8, VERTEX_BUFFER_MAX, allocator, loc)
	white_rect: [16*16*4]u8
	slice.fill(white_rect[:], 255)
	s.shape_drawing_texture = rb.load_texture(white_rect[:], 16, 16)

	s.default_shader = load_shader(string(DEFAULT_SHADER_SOURCE))

	return s
}

/* Returns true if the program wants to shut down. This happens when for example pressing the close
button on the window. The application can decide if it wants to shut down or if it wants to show
some kind of confirmation dialogue and shut down later.

Commonly used for creating the "main loop" of a game.*/
shutdown_wanted :: proc() -> bool {
	return s.shutdown_wanted
}

// Closes the window and cleans up the internal state.
shutdown :: proc() {
	assert(s != nil, "You've called 'shutdown' without calling 'init' first")

	rb.destroy_texture(s.shape_drawing_texture)
	destroy_shader(s.default_shader)
	rb.shutdown()
	delete(s.vertex_buffer_cpu, s.allocator)

	win.shutdown()

	a := s.allocator
	free(s.window_state, a)
	free(s.rb_state, a)
	free(s, a)
	s = nil
}

// Clear the backbuffer with supplied color.
clear :: proc(color: Color) {
	rb.clear(color)
}

// Present the backbuffer. Call at end of frame to make everything you've drawn appear on the screen.
present :: proc() {
	draw_current_batch()
	rb.present()
}

/* Call at start or end of frame to process all events that have arrived to the window.

WARNING: Not calling this will make your program impossible to interact with. */
process_events :: proc() {
	s.keys_went_up = {}
	s.keys_went_down = {}
	s.mouse_delta = {}
	s.mouse_wheel_delta = 0

	win.process_events()

	events := win.get_events()

	for &event in events {
		switch &e in event {
		case Window_Event_Close_Wanted:
			s.shutdown_wanted = true

		case Window_Event_Key_Went_Down:
			s.keys_went_down[e.key] = true
			s.keys_is_held[e.key] = true

		case Window_Event_Key_Went_Up:
			s.keys_is_held[e.key] = false
			s.keys_went_up[e.key] = true

		case Window_Event_Mouse_Move:
			prev_pos := s.mouse_position
			s.mouse_position = e.position
			s.mouse_delta = prev_pos - s.mouse_position

		case Window_Event_Mouse_Wheel:
			s.mouse_wheel_delta = e.delta
		}
	}

	win.clear_events()
}

get_screen_width :: proc() -> int {
	return rb.get_swapchain_width()
}

get_screen_height :: proc() -> int  {
	return rb.get_swapchain_height()
}

set_window_position :: proc(x: int, y: int) {
	win.set_position(x, y)
}

set_window_size :: proc(width: int, height: int) {
	panic("Not implemented")
}

/* Flushes the current batch. This sends off everything to the GPU that has been queued in the
current batch. Normally, you do not need to do this manually. It is done automatically when these
procedures run:
	present
	set_camera
	set_shader

TODO: complete this list and motivate why it needs to happen on those procs (or do that in the
docs for those procs). */   
draw_current_batch :: proc() {
	shader := s.batch_shader.? or_else s.default_shader
	rb.draw(shader, s.batch_texture, s.proj_matrix * s.view_matrix, s.vertex_buffer_cpu[:s.vertex_buffer_cpu_used])
	s.vertex_buffer_cpu_used = 0
}

//-------//
// INPUT //
//-------//

/* Returns true if a keyboard key went down between the current and the previous frame. Set when
'process_events' runs (probably once per frame). */
key_went_down :: proc(key: Keyboard_Key) -> bool {
	return s.keys_went_down[key]
}

/* Returns true if a keyboard key went up (was released) between the current and the previous frame.
Set when 'process_events' runs (probably once per frame). */
key_went_up :: proc(key: Keyboard_Key) -> bool {
	return s.keys_went_up[key]
}

/* Returns true if a keyboard is currently being held down. Set when 'process_events' runs (probably
once per frame). */
key_is_held :: proc(key: Keyboard_Key) -> bool {
	return s.keys_is_held[key]
}

mouse_button_went_down :: proc(button: Mouse_Button) -> bool {
	panic("not implemented")
}

mouse_button_went_up :: proc(button: Mouse_Button) -> bool {
	panic("not implemented")
}

mouse_button_is_held :: proc(button: Mouse_Button) -> bool {
	panic("not implemented")
}

get_mouse_wheel_delta :: proc() -> f32 {
	return s.mouse_wheel_delta
}

get_mouse_position :: proc() -> Vec2 {
	return s.mouse_position
}

//---------//
// DRAWING //
//---------//

draw_rect :: proc(r: Rect, c: Color) {
	if s.batch_texture != TEXTURE_NONE && s.batch_texture != s.shape_drawing_texture {
		draw_current_batch()
	}

	s.batch_texture = s.shape_drawing_texture

	batch_vertex({r.x, r.y}, {0, 0}, c)
	batch_vertex({r.x + r.w, r.y}, {1, 0}, c)
	batch_vertex({r.x + r.w, r.y + r.h}, {1, 1}, c)
	batch_vertex({r.x, r.y}, {0, 0}, c)
	batch_vertex({r.x + r.w, r.y + r.h}, {1, 1}, c)
	batch_vertex({r.x, r.y + r.h}, {0, 1}, c)
}

draw_rect_ex :: proc(r: Rect, origin: Vec2, rot: f32, c: Color) {
	if s.batch_texture != TEXTURE_NONE && s.batch_texture != s.shape_drawing_texture {
		draw_current_batch()
	}

	s.batch_texture = s.shape_drawing_texture
	tl, tr, bl, br: Vec2

	// Rotation adapted from Raylib's "DrawTexturePro"
	if rot == 0 {
		x := r.x - origin.x
		y := r.y - origin.y
		tl = { x,         y }
		tr = { x + r.w, y }
		bl = { x,         y + r.h }
		br = { x + r.w, y + r.h }
	} else {
		sin_rot := math.sin(rot * math.RAD_PER_DEG)
		cos_rot := math.cos(rot * math.RAD_PER_DEG)
		x := r.x
		y := r.y
		dx := -origin.x
		dy := -origin.y

		tl = {
			x + dx * cos_rot - dy * sin_rot,
			y + dx * sin_rot + dy * cos_rot,
		}

		tr = {
			x + (dx + r.w) * cos_rot - dy * sin_rot,
			y + (dx + r.w) * sin_rot + dy * cos_rot,
		}

		bl = {
			x + dx * cos_rot - (dy + r.h) * sin_rot,
			y + dx * sin_rot + (dy + r.h) * cos_rot,
		}

		br = {
			x + (dx + r.w) * cos_rot - (dy + r.h) * sin_rot,
			y + (dx + r.w) * sin_rot + (dy + r.h) * cos_rot,
		}
	}
	
	batch_vertex(tl, {0, 0}, c)
	batch_vertex(tr, {1, 0}, c)
	batch_vertex(br, {1, 1}, c)
	batch_vertex(tl, {0, 0}, c)
	batch_vertex(br, {1, 1}, c)
	batch_vertex(bl, {0, 1}, c)
}

draw_rect_outline :: proc(r: Rect, thickness: f32, color: Color) {
	t := thickness
	
	// Based on DrawRectangleLinesEx from Raylib

	top := Rect {
		r.x,
		r.y,
		r.w,
		t,
	}

	bottom := Rect {
		r.x,
		r.y + r.h - t,
		r.w,
		t,
	}

	left := Rect {
		r.x,
		r.y + t,
		t,
		r.h - t * 2,
	}

	right := Rect {
		r.x + r.w - t,
		r.y + t,
		t,
		r.h - t * 2,
	}

	draw_rect(top, color)
	draw_rect(bottom, color)
	draw_rect(left, color)
	draw_rect(right, color)
}

draw_circle :: proc(center: Vec2, radius: f32, color: Color, segments := 16) {
	if s.batch_texture != TEXTURE_NONE && s.batch_texture != s.shape_drawing_texture {
		draw_current_batch()
	}

	s.batch_texture = s.shape_drawing_texture

	prev := center + {radius, 0}
	for s in 1..=segments {
		sr := (f32(s)/f32(segments)) * 2*math.PI
		rot := linalg.matrix2_rotate(sr)
		p := center + rot * Vec2{radius, 0}
			

		batch_vertex(prev, {0, 0}, color)
		batch_vertex(p, {1, 0}, color)
		batch_vertex(center, {1, 1}, color)

		prev = p
	}
}

draw_line :: proc(start: Vec2, end: Vec2, thickness: f32, color: Color) {
	p := Vec2{start.x, start.y + thickness*0.5}
	s := Vec2{linalg.length(end - start), thickness}

	origin := Vec2 {0, thickness*0.5}
	r := Rect {p.x, p.y, s.x, s.y}

	rot := math.atan2(end.y - start.y, end.x - start.x)

	draw_rect_ex(r, origin, rot * math.DEG_PER_RAD, color)
}

draw_texture :: proc(tex: Texture, pos: Vec2, tint := WHITE) {
	draw_texture_ex(
		tex,
		{0, 0, f32(tex.width), f32(tex.height)},
		{pos.x, pos.y, f32(tex.width), f32(tex.height)},
		{},
		0,
		tint,
	)
}

draw_texture_rect :: proc(tex: Texture, rect: Rect, pos: Vec2, tint := WHITE) {
	draw_texture_ex(
		tex,
		rect,
		{pos.x, pos.y, rect.w, rect.h},
		{},
		0,
		tint,
	)
}

draw_texture_ex :: proc(tex: Texture, src: Rect, dst: Rect, origin: Vec2, rotation: f32, tint := WHITE) {
	if tex.width == 0 || tex.height == 0 {
		return
	}

	if s.batch_texture != TEXTURE_NONE && s.batch_texture != tex.handle {
		draw_current_batch()
	}

	flip_x, flip_y: bool
	src := src
	dst := dst

	if src.w < 0 {
		flip_x = true
		src.w = -src.w
	}

	if src.h < 0 {
		flip_y = true
		src.h = -src.h
	}

	if dst.w < 0 {
		dst.w *= -1
	}

	if dst.h < 0 {
		dst.h *= -1
	}

	s.batch_texture = tex.handle
	tl, tr, bl, br: Vec2

	// Rotation adapted from Raylib's "DrawTexturePro"
	if rotation == 0 {
		x := dst.x - origin.x
		y := dst.y - origin.y
		tl = { x,         y }
		tr = { x + dst.w, y }
		bl = { x,         y + dst.h }
		br = { x + dst.w, y + dst.h }
	} else {
		sin_rot := math.sin(rotation * math.RAD_PER_DEG)
		cos_rot := math.cos(rotation * math.RAD_PER_DEG)
		x := dst.x
		y := dst.y
		dx := -origin.x
		dy := -origin.y

		tl = {
			x + dx * cos_rot - dy * sin_rot,
			y + dx * sin_rot + dy * cos_rot,
		}

		tr = {
			x + (dx + dst.w) * cos_rot - dy * sin_rot,
			y + (dx + dst.w) * sin_rot + dy * cos_rot,
		}

		bl = {
			x + dx * cos_rot - (dy + dst.h) * sin_rot,
			y + dx * sin_rot + (dy + dst.h) * cos_rot,
		}

		br = {
			x + (dx + dst.w) * cos_rot - (dy + dst.h) * sin_rot,
			y + (dx + dst.w) * sin_rot + (dy + dst.h) * cos_rot,
		}
	}
	
	ts := Vec2{f32(tex.width), f32(tex.height)}
	up := Vec2{src.x, src.y} / ts
	us := Vec2{src.w, src.h} / ts
	c := tint

	uv0 := up
	uv1 := up + {us.x, 0}
	uv2 := up + us
	uv3 := up
	uv4 := up + us
	uv5 := up + {0, us.y}

	if flip_x {
		uv0.x += us.x
		uv1.x -= us.x
		uv2.x -= us.x
		uv3.x += us.x
		uv4.x -= us.x
		uv5.x += us.x		
	}

	if flip_y {
		uv0.y += us.y
		uv1.y += us.y
		uv2.y -= us.y
		uv3.y += us.y
		uv4.y -= us.y
		uv5.y -= us.y		
	}

	batch_vertex(tl, uv0, c)
	batch_vertex(tr, uv1, c)
	batch_vertex(br, uv2, c)
	batch_vertex(tl, uv3, c)
	batch_vertex(br, uv4, c)
	batch_vertex(bl, uv5, c)
}

draw_text :: proc(text: string, pos: Vec2, font_size: f32, color: Color) {
	
}

//--------------------//
// TEXTURE MANAGEMENT //
//--------------------//

load_texture_from_file :: proc(filename: string) -> Texture {
	img, img_err := image.load_from_file(filename, options = {.alpha_add_if_missing}, allocator = context.temp_allocator)

	if img_err != nil {
		log.errorf("Error loading texture %v: %v", filename, img_err)
		return {}
	}

	backend_tex := rb.load_texture(img.pixels.buf[:], img.width, img.height)

	return {
		handle = backend_tex,
		width = img.width,
		height = img.height,
	}
}

destroy_texture :: proc(tex: Texture) {
	rb.destroy_texture(tex.handle)
}


//---------//
// SHADERS //
//---------//

load_shader :: proc(shader_source: string, layout_formats: []Shader_Input_Format = {}) -> Shader {
	handle, desc := rb.load_shader(shader_source, context.temp_allocator, layout_formats)

	if handle == SHADER_NONE {
		log.error("Failed loading shader")
		return {}
	}

	shd := Shader {
		handle = handle,
		constant_buffers = make([]Shader_Constant_Buffer, len(desc.constant_buffers), s.allocator),
		constant_lookup = make(map[string]Shader_Constant_Location, s.allocator),
		inputs = slice.clone(desc.inputs, s.allocator),
		input_overrides = make([]Shader_Input_Value_Override, len(desc.inputs), s.allocator),
	}

	for &input in shd.inputs {
		input.name = strings.clone(input.name, s.allocator)
	}

	for cb_idx in 0..<len(desc.constant_buffers) {
		cb_desc := &desc.constant_buffers[cb_idx]

		shd.constant_buffers[cb_idx] = {
			cpu_data = make([]u8, desc.constant_buffers[cb_idx].size, s.allocator),
		}

		for &v in cb_desc.variables {
			if v.name == "" {
				continue
			}

			shd.constant_lookup[strings.clone(v.name, s.allocator)] = v.loc

			switch v.name {
			case "mvp":
				shd.constant_builtin_locations[.MVP] = v.loc
			}
		}
	}

	for &d in shd.default_input_offsets {
		d = -1
	}
	input_offset: int

	for &input in shd.inputs {
		default_format := get_shader_input_default_type(input.name, input.type)

		if default_format != .Unknown {
			shd.default_input_offsets[default_format] = input_offset
		}
		
		input_offset += shader_input_format_size(input.format)
	}

	shd.vertex_size = input_offset

	return shd
}

destroy_shader :: proc(shader: Shader) {
	rb.destroy_shader(shader.handle)

	for c in shader.constant_buffers {
		delete(c.cpu_data)
	}
	
	delete(shader.constant_buffers)

	for k, _ in shader.constant_lookup {
		delete(k)
	}

	delete(shader.constant_lookup)
	for i in shader.inputs {
		delete(i.name)
	}
	delete(shader.inputs)
	delete(shader.input_overrides)
}

get_default_shader :: proc() -> Shader {
	return s.default_shader
}

set_shader :: proc(shader: Maybe(Shader)) {
	if maybe_handle_equal(shader, s.batch_shader) {
		return
	}

	draw_current_batch()
	s.batch_shader = shader
}

set_shader_constant :: proc(shd: Shader, loc: Shader_Constant_Location, val: any) {
	draw_current_batch()

	if int(loc.buffer_idx) >= len(shd.constant_buffers) {
		log.warnf("Constant buffer idx %v is out of bounds", loc.buffer_idx)
		return
	}

	sz := reflect.size_of_typeid(val.id)
	b := &shd.constant_buffers[loc.buffer_idx]

	if int(loc.offset) + sz > len(b.cpu_data) {
		log.warnf("Constant buffer idx %v is trying to be written out of bounds by at offset %v with %v bytes", loc.buffer_idx, loc.offset, size_of(val))
		return
	}

	mem.copy(&b.cpu_data[loc.offset], val.data, sz)
}

override_shader_input :: proc(shader: Shader, input: int, val: any) {
	sz := reflect.size_of_typeid(val.id)
	assert(sz < SHADER_INPUT_VALUE_MAX_SIZE)
	if input >= len(shader.input_overrides) {
		log.errorf("Input override out of range. Wanted to override input %v, but shader only has %v inputs", input, len(shader.input_overrides))
		return
	}

	o := &shader.input_overrides[input]

	o.val = {}

	if sz > 0 {
		mem.copy(raw_data(&o.val), val.data, sz)
	}

	o.used = sz
}

shader_input_format_size :: proc(f: Shader_Input_Format) -> int {
	switch f {
	case .Unknown: return 0
	case .RGBA32_Float: return 32
	case .RGBA8_Norm: return 4
	case .RGBA8_Norm_SRGB: return 4
	case .RGB32_Float: return 12
	case .RG32_Float: return 8
	case .R32_Float: return 4
	}

	return 0
}

//-------------------------------//
// CAMERA AND COORDINATE SYSTEMS //
//-------------------------------//

set_camera :: proc(camera: Maybe(Camera)) {
	if camera == s.batch_camera {
		return
	}

	draw_current_batch()
	s.batch_camera = camera
	s.proj_matrix = make_default_projection(s.width, s.height)

	if c, c_ok := camera.?; c_ok {
		origin_trans := linalg.matrix4_translate(vec3_from_vec2(-c.origin))
		translate := linalg.matrix4_translate(vec3_from_vec2(c.target))
		scale := linalg.matrix4_scale(Vec3{1/c.zoom, 1/c.zoom, 1})
		rot := linalg.matrix4_rotate_f32(c.rotation * math.RAD_PER_DEG, {0, 0, 1})
		camera_matrix := translate * scale * rot * origin_trans
		s.view_matrix = linalg.inverse(camera_matrix)
	} else {
		s.view_matrix = 1
	}
}

screen_to_world :: proc(pos: Vec2, camera: Camera) -> Vec2 {
	panic("not implemented")
}

//------//
// MISC //
//------//

set_scissor_rect :: proc(scissor_rect: Maybe(Rect)) {
	panic("not implemented")
}

/* Restore the internal state using the pointer returned by `init`. Useful after reloading the
library (for example, when doing code hot reload). */
set_internal_state :: proc(state: ^State) {
	s = state
	rb = s.rb
	win = s.win
	rb.set_internal_state(s.rb_state)
	win.set_internal_state(s.window_state)
}

//---------------------//
// TYPES AND CONSTANTS //
//---------------------//

// A RGBA (Red, Greeen, Blue, Alpha) color. Each channel can have a value between 0 and 255.
Color :: [4]u8

// A two dimensinal vector.
Vec2 :: [2]f32

// A three dimensinal vector.
Vec3 :: [3]f32

// A 4x4 column-major matrix.
Mat4 :: matrix[4,4]f32

// A two dimensional vector of integer numeric type.
Vec2i :: [2]int

// A rectangle that sits at position (x, y) and has size (w, h).
Rect :: struct {
	x, y: f32,
	w, h: f32,
}

Texture :: struct {
	handle: Texture_Handle,
	width: int,
	height: int,
}

Camera :: struct {
	target: Vec2,
	origin: Vec2,
	rotation: f32,
	zoom: f32,
}

Shader_Handle :: distinct Handle

SHADER_NONE :: Shader_Handle {}

Shader :: struct {
	handle: Shader_Handle,
	constant_buffers: []Shader_Constant_Buffer,
	constant_lookup: map[string]Shader_Constant_Location,
	constant_builtin_locations: [Shader_Builtin_Constant]Maybe(Shader_Constant_Location),

	inputs: []Shader_Input,
	input_overrides: []Shader_Input_Value_Override,
	default_input_offsets: [Shader_Default_Inputs]int,
	vertex_size: int,
}

Shader_Constant_Buffer :: struct {
	cpu_data: []u8,
}

SHADER_INPUT_VALUE_MAX_SIZE :: 256

Shader_Input_Value_Override :: struct {
	val: [SHADER_INPUT_VALUE_MAX_SIZE]u8,
	used: int,
}


Shader_Input_Type :: enum {
	F32,
	Vec2,
	Vec3,
	Vec4,
}

Shader_Builtin_Constant :: enum {
	MVP,
}

Shader_Default_Inputs :: enum {
	Unknown,
	Position,
	UV,
	Color,
}

Shader_Input :: struct {
	name: string,
	register: int,
	type: Shader_Input_Type,
	format: Shader_Input_Format,
}

Shader_Constant_Location :: struct {
	buffer_idx: u32,
	offset: u32,
}

Shader_Input_Format :: enum {
	Unknown,
	RGBA32_Float,
	RGBA8_Norm,
	RGBA8_Norm_SRGB,
	RGB32_Float,
	RG32_Float,
	R32_Float,
}

Handle :: hm.Handle
Texture_Handle :: distinct Handle
TEXTURE_NONE :: Texture_Handle {}

/* This keeps track of the internal state of the library. Usually, you do not need to poke at it.
It is created and kept as a global variable when 'init' is called. However, 'init' also returns the
pointer to it, so you can later use 'set_internal_state' to restore it (after for example hot
reload). */
State :: struct {
	allocator: runtime.Allocator,
	custom_context: runtime.Context,
	win: Window_Interface,
	window_state: rawptr,
	rb: Rendering_Backend_Interface,
	rb_state: rawptr,
	
	shutdown_wanted: bool,

	mouse_position: Vec2,
	mouse_delta: Vec2,
	mouse_wheel_delta: f32,

	keys_went_down: #sparse [Keyboard_Key]bool,
	keys_went_up: #sparse [Keyboard_Key]bool,
	keys_is_held: #sparse [Keyboard_Key]bool,

	window: Window_Handle,
	width: int,
	height: int,

	shape_drawing_texture: Texture_Handle,
	batch_camera: Maybe(Camera),
	batch_shader: Maybe(Shader),
	batch_texture: Texture_Handle,

	view_matrix: Mat4,
	proj_matrix: Mat4,

	vertex_buffer_cpu: []u8,
	vertex_buffer_cpu_used: int,
	default_shader: Shader,
}

// Support for up to 255 mouse buttons. Cast an int to type `Mouse_Button` to use things outside the
// options presented here.
Mouse_Button :: enum {
	Left,
	Right,
	Middle,
	Max = 255,
}

WHITE :: Color { 255, 255, 255, 255 }
BLACK :: Color { 0, 0, 0, 255 }
BLANK :: Color { 0, 0, 0, 0}

// These are from Raylib. They are here so you can easily port a Raylib program to Karl2D.
RL_LIGHTGRAY  :: Color { 200, 200, 200, 255 }
RL_GRAY       :: Color { 130, 130, 130, 255 }
RL_DARKGRAY   :: Color { 80, 80, 80, 255 }
RL_YELLOW     :: Color { 253, 249, 0, 255 }
RL_GOLD       :: Color { 255, 203, 0, 255 }
RL_ORANGE     :: Color { 255, 161, 0, 255 }
RL_PINK       :: Color { 255, 109, 194, 255 }
RL_RED        :: Color { 230, 41, 55, 255 }
RL_MAROON     :: Color { 190, 33, 55, 255 }
RL_GREEN      :: Color { 0, 228, 48, 255 }
RL_LIME       :: Color { 0, 158, 47, 255 }
RL_DARKGREEN  :: Color { 0, 117, 44, 255 }
RL_SKYBLUE    :: Color { 102, 191, 255, 255 }
RL_BLUE       :: Color { 0, 121, 241, 255 }
RL_DARKBLUE   :: Color { 0, 82, 172, 255 }
RL_PURPLE     :: Color { 200, 122, 255, 255 }
RL_VIOLET     :: Color { 135, 60, 190, 255 }
RL_DARKPURPLE :: Color { 112, 31, 126, 255 }
RL_BEIGE      :: Color { 211, 176, 131, 255 }
RL_BROWN      :: Color { 127, 106, 79, 255 }
RL_DARKBROWN  :: Color { 76, 63, 47, 255 }
RL_WHITE      :: WHITE
RL_BLACK      :: BLACK
RL_BLANK      :: BLANK
RL_MAGENTA    :: Color { 255, 0, 255, 255 }
RL_RAYWHITE   :: Color { 245, 245, 245, 255 }


// Based on Raylib / GLFW
Keyboard_Key :: enum {
	None            = 0,

	// Alphanumeric keys
	Apostrophe      = 39,
	Comma           = 44,
	Minus           = 45,
	Period          = 46,
	Slash           = 47,
	Zero            = 48,
	One             = 49,
	Two             = 50,
	Three           = 51,
	Four            = 52,
	Five            = 53,
	Six             = 54,
	Seven           = 55,
	Eight           = 56,
	Nine            = 57,
	Semicolon       = 59,
	Equal           = 61,
	A               = 65,
	B               = 66,
	C               = 67,
	D               = 68,
	E               = 69,
	F               = 70,
	G               = 71,
	H               = 72,
	I               = 73,
	J               = 74,
	K               = 75,
	L               = 76,
	M               = 77,
	N               = 78,
	O               = 79,
	P               = 80,
	Q               = 81,
	R               = 82,
	S               = 83,
	T               = 84,
	U               = 85,
	V               = 86,
	W               = 87,
	X               = 88,
	Y               = 89,
	Z               = 90,
	Left_Bracket    = 91,
	Backslash       = 92,
	Right_Bracket   = 93,
	Grave           = 96,

	// Function keys
	Space           = 32,
	Escape          = 256,
	Enter           = 257,
	Tab             = 258,
	Backspace       = 259,
	Insert          = 260,
	Delete          = 261,
	Right           = 262,
	Left            = 263,
	Down            = 264,
	Up              = 265,
	Page_Up         = 266,
	Page_Down       = 267,
	Home            = 268,
	End             = 269,
	Caps_Lock       = 280,
	Scroll_Lock     = 281,
	Num_Lock        = 282,
	Print_Screen    = 283,
	Pause           = 284,
	F1              = 290,
	F2              = 291,
	F3              = 292,
	F4              = 293,
	F5              = 294,
	F6              = 295,
	F7              = 296,
	F8              = 297,
	F9              = 298,
	F10             = 299,
	F11             = 300,
	F12             = 301,
	Left_Shift      = 340,
	Left_Control    = 341,
	Left_Alt        = 342,
	Left_Super      = 343,
	Right_Shift     = 344,
	Right_Control   = 345,
	Right_Alt       = 346,
	Right_Super     = 347,
	Menu            = 348,

	// Keypad keys
	KP_0            = 320,
	KP_1            = 321,
	KP_2            = 322,
	KP_3            = 323,
	KP_4            = 324,
	KP_5            = 325,
	KP_6            = 326,
	KP_7            = 327,
	KP_8            = 328,
	KP_9            = 329,
	KP_Decimal      = 330,
	KP_Divide       = 331,
	KP_Multiply     = 332,
	KP_Subtract     = 333,
	KP_Add          = 334,
	KP_Enter        = 335,
	KP_Equal        = 336,
}

// Used by API builder. Everything after this constant will not be in karl2d_api.txt
API_END :: true

batch_vertex :: proc(v: Vec2, uv: Vec2, color: Color) {
	v := v

	if s.vertex_buffer_cpu_used == len(s.vertex_buffer_cpu) {
		panic("Must dispatch here")
	}

	shd := s.batch_shader.? or_else s.default_shader

	base_offset := s.vertex_buffer_cpu_used
	pos_offset := shd.default_input_offsets[.Position]
	uv_offset := shd.default_input_offsets[.UV]
	color_offset := shd.default_input_offsets[.Color]
	
	mem.set(&s.vertex_buffer_cpu[base_offset], 0, shd.vertex_size)

	if pos_offset != -1 {
		(^Vec2)(&s.vertex_buffer_cpu[base_offset + pos_offset])^ = {v.x, v.y}
	}

	if uv_offset != -1 {
		(^Vec2)(&s.vertex_buffer_cpu[base_offset + uv_offset])^ = uv
	}

	if color_offset != -1 {
		(^Color)(&s.vertex_buffer_cpu[base_offset + color_offset])^ = color
	}

	override_offset: int
	for &o, idx in shd.input_overrides {
		input := &shd.inputs[idx]
		sz := shader_input_format_size(input.format)

		if o.used != 0 {
			mem.copy(&s.vertex_buffer_cpu[base_offset + override_offset], raw_data(&o.val), o.used)
		}

		override_offset += sz
	}
	
	s.vertex_buffer_cpu_used += shd.vertex_size
}


VERTEX_BUFFER_MAX :: 1000000
DEFAULT_SHADER_SOURCE :: #load("shader.hlsl")

@(private="file")
s: ^State
win: Window_Interface
rb: Rendering_Backend_Interface

maybe_handle_equal :: proc(m1: Maybe($T), m2: Maybe(T)) -> bool {
	if m1 == nil && m2 == nil {
		return true
	}

	m1v, m1v_ok := m1.?
	m2v, m2v_ok := m2.?

	if !m1v_ok || !m2v_ok {
		return false
	}

	return m1v.handle == m2v.handle
}

get_shader_input_default_type :: proc(name: string, type: Shader_Input_Type) -> Shader_Default_Inputs {
	if name == "POS" && type == .Vec2 {
		return .Position
	} else if name == "UV" && type == .Vec2 {
		return .UV
	} else if name == "COL" && type == .Vec4 {
		return .Color
	}

	return .Unknown
}

get_shader_input_format :: proc(name: string, type: Shader_Input_Type) -> Shader_Input_Format {
	default_type := get_shader_input_default_type(name, type)

	if default_type != .Unknown {
		switch default_type {
		case .Position: return .RG32_Float
		case .UV: return .RG32_Float
		case .Color: return .RGBA8_Norm
		case .Unknown: unreachable()
		}
	}

	switch type {
	case .F32: return .R32_Float
	case .Vec2: return .RG32_Float
	case .Vec3: return .RGB32_Float
	case .Vec4: return .RGBA32_Float
	}

	return .Unknown
}

vec3_from_vec2 :: proc(v: Vec2) -> Vec3 {
	return {
		v.x, v.y, 0,
	}
}

temp_cstring :: proc(str: string, loc := #caller_location) -> cstring {
	return strings.clone_to_cstring(str, context.temp_allocator, loc)
}

make_default_projection :: proc(w, h: int) -> matrix[4,4]f32 {
	return linalg.matrix_ortho3d_f32(0, f32(w), f32(h), 0, 0.001, 2)
}

_ :: bmp
_ :: png
_ :: tga