raylib Data Flow — Overview

The mental model in one paragraph

raylib is a modular C library built around two mandatory pieces — rcore (window, input, timing) and rlgl (OpenGL abstraction) — plus optional modules for shapes, textures, text, 3D models, and audio. You call InitWindow(), which boots a platform backend (GLFW by default), creates an OpenGL context, and initializes rlgl's default shader and render batch. Each frame you call BeginDrawing(), issue draw calls that accumulate geometry into a batch, then EndDrawing() flushes the batch, swaps buffers, limits FPS, and polls input. There is no built-in scene graph or entity system — just functions.

Interactive architecture map

Tap a module to see what it does and how it fits. Mandatory modules are marked.

Module

Select a module above.

Frame loop simulator

What EndDrawing() does each frame on desktop (when SUPPORT_CUSTOM_FRAME_CONTROL is off). Use Step or Play on mobile.

0Frame #

Poll inputCurrent phase

0Batch vertices

Layer diagram

  YOUR CODE                    RAYLIB MODULES                 PLATFORM / GPU
 ┌─────────────┐            ┌──────────────────┐           ┌─────────────────┐
 │ main()      │  InitWindow│ rcore.c          │InitPlatform│ rcore_desktop_  │
 │ while loop  │───────────►│  CORE global     │───────────►│ glfw.c          │
 │ Draw*()     │            │  BeginDrawing    │           │  GLFW window    │
 └─────────────┘            │  EndDrawing      │           │  GL context     │
       │                    └────────┬─────────┘           └────────┬────────┘
       │                             │ rlglInit / rlBegin            │ glfwSwapBuffers
       ▼                             ▼                               ▼
 DrawRectangle ──► rshapes ──► rlgl batch ──► glDrawElements ──► framebuffer
 DrawTexture  ──► rtextures ──► rlLoadTexture
 DrawModel    ──► rmodels  ──► DrawMesh (VAO, bypasses batch)
 PlaySound    ──► raudio   ──► miniaudio callback (separate thread)

One frame, end to end

Tap a step to jump to its explanation below.

0. Startup: InitWindow

InitWindow in rcore.c initializes CORE.Window and CORE.Input, calls platform InitPlatform() (e.g. GLFW window + GL context), then rlglInit(width, height) which creates the 1×1 default texture, default shader, and render batch.

rcore.c L585–720 — InitWindow

Full detail: Frame lifecycle.

1. BeginDrawing resets the frame

BeginDrawing captures update-phase delta time and resets the modelview matrix, applying CORE.Window.screenScale for HiDPI displays. It does not clear the screen — call ClearBackground yourself.

rcore.c L858–872 — BeginDrawing

2. Draw calls batch 2D geometry

Even solid rectangles bind a shared white texture and emit quads via rlBegin(RL_QUADS). Text draws each glyph with DrawTexturePro. State changes (new texture/shader) or buffer overflow trigger a batch flush mid-frame.

rshapes.c L738–795 — DrawRectanglePro

Full detail: rlgl & batching.

3. EndDrawing flushes the batch

The first line of EndDrawing is rlDrawRenderBatchActive(), which uploads accumulated vertices and draws with the active shader (default MVP + texture0).

rcore.c L875–917 — EndDrawing

4. Buffer swap and frame pacing

Unless custom frame control is enabled, EndDrawing calls SwapScreenBuffer() (platform), measures draw time, WaitTime() to hit SetTargetFPS, then PollInputEvents().

rcore_desktop_glfw.c — PollInputEvents

5. Input is edge-detected per frame

IsKeyPressed returns true when a key transitioned from up to down since the last poll. Window close is tracked in CORE.Window.shouldClose, updated from GLFW each frame.

rcore.c L3802–3812 — IsKeyPressed

Core objects

Object	Role	Defined in
`CORE`	Global window, input, timing state	`rcore.c`
`RLGL`	Render batch, shaders, GL state	`rlgl.h`
`Image`	CPU pixel buffer (RAM)	`raylib.h`
`Texture2D`	GPU texture handle + metadata	`raylib.h`
`Font`	Glyph atlas texture + metrics	`raylib.h`
`Mesh` / `Model`	3D geometry + materials on GPU	`raylib.h`
`Sound`	Static audio buffer in mixer list	`raudio.c`

Component pages

Frame lifecycle — InitWindow, loop, EndDrawing, CloseWindow
rlgl & batching — immediate mode, flush rules, interactive batch demo
Platform backends — compile-time selection, GLFW boot
Textures & images — LoadFileData → stb → rlLoadTexture
Models & 3D — LoadModel, DrawMesh, BeginMode3D
Audio system — miniaudio callback mixing
Modules & build — config.h, Make, CMake, Zig

From InitWindow to pixels on screen