SDL2 multimedia — window, 2D hardware-accelerated renderer, textures, keyboard/mouse events, audio, and TrueType fonts.

Overview

SDL2 is the standard cross-platform multimedia library for games and interactive applications. It provides a hardware-accelerated 2D renderer backed by OpenGL or Direct3D, an input event system, audio playback (via SDL_mixer), image loading (via SDL_image), and TrueType text (via SDL_ttf).

Game Loop

uses sdl2;

Init();
var win := CreateWindow('My Game', -1, -1, 800, 600, False, False, False);
var rnd := CreateRenderer(win, True);  { VSync on }

var tex    := LoadTexture(rnd, 'assets/player.png');
var font   := LoadFont('assets/font.ttf', 20);
var music  := LoadMusic('assets/bgm.ogg');
OpenAudio(44100, 2, 2048);
PlayMusic(music, -1);  { loop forever }

var running := True;
var px := 100;
var ev: TSDLEvent;

while running do
begin
  { Events }
  while PollEvent(ev) do
  begin
    if ev.EventType = SDL_QUIT then running := False;
    if (ev.EventType = SDL_KEYDOWN) and (ev.Scancode = SDL_SCANCODE_ESCAPE) then
      running := False;
  end;

  { Update }
  if IsKeyPressed(SDL_SCANCODE_RIGHT) then px := px + 3;
  if IsKeyPressed(SDL_SCANCODE_LEFT)  then px := px - 3;

  { Render }
  SetRenderDrawColor(rnd, 20, 20, 30, 255);
  RenderClear(rnd);

  var dst: TSDLRect;
  dst.X := px; dst.Y := 250; dst.W := 64; dst.H := 64;
  RenderCopyTexture(rnd, tex, dst);

  DrawText(rnd, font, 'Use arrow keys', 10, 10, 255, 255, 255);
  RenderPresent(rnd);
end;

HaltMusic();
FreeMusic(music);
CloseFont(font);
DestroyTexture(tex);
DestroyRenderer(rnd);
DestroyWindow(win);
Quit();

Drawing Primitives

{ Colored rectangle }
SetRenderDrawColor(rnd, 255, 100, 0, 255);
var r: TSDLRect;
r.X := 50; r.Y := 50; r.W := 200; r.H := 100;
RenderFillRect(rnd, r);

{ Border only }
SetRenderDrawColor(rnd, 255, 255, 0, 255);
RenderDrawRect(rnd, r);

{ Diagonal line }
SetRenderDrawColor(rnd, 0, 200, 255, 255);
RenderDrawLine(rnd, 0, 0, 800, 600);

{ Filled circle }
SetRenderDrawColor(rnd, 200, 50, 200, 255);
RenderFillCircle(rnd, 400, 300, 50);

Sprites with Rotation & Flip

var sprite := LoadTexture(rnd, 'ship.png');
SetTextureAlpha(sprite, 200);  { semi-transparent }

var src: TSDLRect; src.X := 0; src.Y := 0; src.W := 32; src.H := 32;
var dst2: TSDLRect; dst2.X := 300; dst2.Y := 200; dst2.W := 64; dst2.H := 64;

{ Rotate 45 degrees, no flip }
RenderCopyEx(rnd, sprite, src, dst2, 45.0, False, False);

{ Horizontal flip }
RenderCopyEx(rnd, sprite, src, dst2, 0, True, False);

Audio

OpenAudio(44100, 2, 2048);   { 44.1 kHz stereo }

var bgm   := LoadMusic('bgm.ogg');
var jump  := LoadSound('jump.wav');
var explosion := LoadSound('boom.wav');

SetMusicVolume(64);    { 50% volume }
PlayMusic(bgm, -1);   { loop forever }

PlaySound(jump, -1, 0);       { auto channel, no loop }
PlaySound(explosion, 2, 0);   { channel 2, no loop }
SetSoundVolume(-1, 96);      { set all channels to 75% }

PauseMusic();
ResumeMusic();
HaltMusic();
FreeMusic(bgm);
FreeSound(jump);
CloseAudio();

API Reference

Init & Window

Function	Description
Init	Initialize SDL2 (video, audio, events).
Quit	Shutdown all SDL2 subsystems.
GetTicks	Milliseconds elapsed since Init.
Delay(Ms)	Sleep for Ms milliseconds.
CreateWindow(Title, X, Y, W, H, Fullscreen, Resizable, Borderless)	Create a window. -1/-1 for centered position.
CreateWindowFullscreen(Title)	Fullscreen at native resolution.
DestroyWindow(Win)	Close and destroy window.
SetWindowTitle(Win, Title)	Change window title.
GetWindowSize(Win, W, H)	Get drawable size (accounts for high-DPI).

Renderer & Primitives

Function	Description
CreateRenderer(Win, VSync)	Hardware-accelerated 2D renderer.
SetRenderDrawColor(Rnd, R,G,B,A)	Set draw color (0–255).
RenderClear(Rnd)	Fill screen with draw color.
RenderPresent(Rnd)	Flip buffer to screen.
RenderDrawLine/Lines/Point/Rect/FillRect/FillCircle	Geometric primitives.
SetRenderScale(Rnd, SX, SY)	Virtual resolution scaling.

Textures

Function	Description
LoadTexture(Rnd, Path)	Load PNG/JPG/BMP as GPU texture.
CreateTexture(Rnd, W, H)	Blank texture (for render-to-texture).
SetTextureAlpha(Tex, Alpha)	Transparency 0–255.
SetTextureColorMod(Tex, R,G,B)	Tint/color multiply.
RenderCopyTexture(Rnd, Tex, Dst)	Draw texture to rect.
RenderCopyEx(Rnd, Tex, Src, Dst, Angle, FlipH, FlipV)	Draw with rotation and flip.
RenderCopyF(Rnd, Tex, Dst)	Draw with floating-point rect.
DestroyTexture(Tex)	Free texture.

Events & Input

Function	Description
PollEvent(Event)	Get next event. Returns False if queue is empty.
WaitEvent(Event)	Block until an event arrives.
IsKeyPressed(Scancode)	Check if a key is currently held.
GetKeyboardState	Snapshot of all key states.
GetMouseState(X, Y, Buttons)	Current mouse position and buttons.
WarpMouse(Win, X, Y)	Move cursor to position.
ShowCursor(Visible)	Show or hide the mouse cursor.
SetRelativeMouseMode(Enable)	FPS-style relative mouse capture.

Fonts, Audio

Function	Description
LoadFont(Path, Size)	Load TrueType font at point size.
DrawText(Rnd, Font, Text, X, Y, R,G,B)	Render text directly to renderer.
RenderTextBlended(Rnd, Font, Text, R,G,B,A)	Anti-aliased text as texture.
MeasureText(Font, Text, W, H)	Get text pixel dimensions.
OpenAudio(Freq, Channels, ChunkSize)	Init audio mixer.
LoadMusic(Path) / PlayMusic / PauseMusic / HaltMusic	Background music control.
LoadSound(Path) / PlaySound(Sound, Channel, Loops)	Sound effect playback.
SetMusicVolume / SetSoundVolume(Ch, Vol)	Volume 0–128.