▼SDL3:   Racket Bindings for SDL3
►25 Open  GL
On this page:
25.1 Creating Contexts
create-gl-context
gl-context?
gl-make-current!
gl-swap-window!
25.2 Open  GL Attributes
gl-set-attribute!
gl-get-attribute
25.2.1 Attribute Constants
25.2.1.1 Buffer Sizes
SDL_  GL_  RED_  SIZE
SDL_  GL_  GREEN_  SIZE
SDL_  GL_  BLUE_  SIZE
SDL_  GL_  ALPHA_  SIZE
SDL_  GL_  BUFFER_  SIZE
SDL_  GL_  DEPTH_  SIZE
SDL_  GL_  STENCIL_  SIZE
25.2.1.2 Accumulation Buffer
SDL_  GL_  ACCUM_  RED_  SIZE
SDL_  GL_  ACCUM_  GREEN_  SIZE
SDL_  GL_  ACCUM_  BLUE_  SIZE
SDL_  GL_  ACCUM_  ALPHA_  SIZE
25.2.1.3 Multisampling
SDL_  GL_  MULTISAMPLEBUFFERS
SDL_  GL_  MULTISAMPLESAMPLES
25.2.1.4 Context Settings
SDL_  GL_  DOUBLEBUFFER
SDL_  GL_  STEREO
SDL_  GL_  ACCELERATED_  VISUAL
SDL_  GL_  RETAINED_  BACKING
SDL_  GL_  FRAMEBUFFER_  SRGB_  CAPABLE
SDL_  GL_  FLOATBUFFERS
25.2.1.5 Context Version and Profile
SDL_  GL_  CONTEXT_  MAJOR_  VERSION
SDL_  GL_  CONTEXT_  MINOR_  VERSION
SDL_  GL_  CONTEXT_  PROFILE_  MASK
SDL_  GL_  CONTEXT_  FLAGS
25.2.1.6 Context Profiles
SDL_  GL_  CONTEXT_  PROFILE_  CORE
SDL_  GL_  CONTEXT_  PROFILE_  COMPATIBILITY
SDL_  GL_  CONTEXT_  PROFILE_  ES
25.2.1.7 Context Flags
SDL_  GL_  CONTEXT_  DEBUG_  FLAG
SDL_  GL_  CONTEXT_  FORWARD_  COMPATIBLE_  FLAG
SDL_  GL_  CONTEXT_  ROBUST_  ACCESS_  FLAG
SDL_  GL_  CONTEXT_  RESET_  ISOLATION_  FLAG
25.2.1.8 Other
SDL_  GL_  SHARE_  WITH_  CURRENT_  CONTEXT
SDL_  GL_  CONTEXT_  RELEASE_  BEHAVIOR
SDL_  GL_  CONTEXT_  RESET_  NOTIFICATION
SDL_  GL_  CONTEXT_  NO_  ERROR
SDL_  GL_  EGL_  PLATFORM
25.3 Swap Interval (VSync)
gl-set-swap-interval!
gl-get-swap-interval
9.0.0.11
Racket
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25 OpenGL🔗ℹ

This section covers OpenGL context management for use with external OpenGL libraries.

Note: This module provides context management only. For actual OpenGL rendering, use a separate OpenGL binding library.

25.1 Creating Contexts🔗ℹ

procedure

(create-gl-context window [#:custodian cust]) → gl-context?

  window : window?
  cust : custodian? = (current-custodian)
Creates an OpenGL context for a window.

The window should be created with OpenGL support enabled.

;; Set up OpenGL attributes before creating window
(gl-set-attribute! SDL_GL_CONTEXT_MAJOR_VERSION 3)
(gl-set-attribute! SDL_GL_CONTEXT_MINOR_VERSION 3)
(gl-set-attribute! SDL_GL_CONTEXT_PROFILE_MASK SDL_GL_CONTEXT_PROFILE_CORE)
 
;; Create window with OpenGL flag
(define win (make-window "OpenGL" 800 600 #:flags '(opengl)))
 
;; Create context
(define ctx (create-gl-context win))
(gl-make-current! win ctx)

procedure

(gl-context? v) → boolean?

  v : any/c
Returns #t if v is an OpenGL context.

procedure

(gl-make-current! window ctx) → void?

  window : window?
  ctx : gl-context?
Makes an OpenGL context current for a window.

This must be called before issuing OpenGL commands.

procedure

(gl-swap-window! window) → void?

  window : window?
Swaps the OpenGL buffers for a window.

Call this after rendering to display the frame.

25.2 OpenGL Attributes🔗ℹ

OpenGL attributes control context creation. Set them before creating a context.

procedure

(gl-set-attribute! attr value) → void?

  attr : exact-nonnegative-integer?
  value : exact-integer?
Sets an OpenGL attribute.

;; Request OpenGL 4.1 core profile
(gl-set-attribute! SDL_GL_CONTEXT_MAJOR_VERSION 4)
(gl-set-attribute! SDL_GL_CONTEXT_MINOR_VERSION 1)
(gl-set-attribute! SDL_GL_CONTEXT_PROFILE_MASK SDL_GL_CONTEXT_PROFILE_CORE)
 
;; Request double buffering with 24-bit depth
(gl-set-attribute! SDL_GL_DOUBLEBUFFER 1)
(gl-set-attribute! SDL_GL_DEPTH_SIZE 24)

procedure

(gl-get-attribute attr) → exact-integer?

  attr : exact-nonnegative-integer?
Gets an OpenGL attribute value.

25.2.1 Attribute Constants🔗ℹ

25.2.1.1 Buffer Sizes🔗ℹ

value

SDL_GL_RED_SIZE : exact-nonnegative-integer?

Red channel bits.

value

SDL_GL_GREEN_SIZE : exact-nonnegative-integer?

Green channel bits.

value

SDL_GL_BLUE_SIZE : exact-nonnegative-integer?

Blue channel bits.

value

SDL_GL_ALPHA_SIZE : exact-nonnegative-integer?

Alpha channel bits.

value

SDL_GL_BUFFER_SIZE : exact-nonnegative-integer?

Total color buffer bits.

value

SDL_GL_DEPTH_SIZE : exact-nonnegative-integer?

Depth buffer bits.

value

SDL_GL_STENCIL_SIZE : exact-nonnegative-integer?

Stencil buffer bits.

25.2.1.2 Accumulation Buffer🔗ℹ

value

SDL_GL_ACCUM_RED_SIZE : exact-nonnegative-integer?

Accumulation red bits.

value

SDL_GL_ACCUM_GREEN_SIZE : exact-nonnegative-integer?

Accumulation green bits.

value

SDL_GL_ACCUM_BLUE_SIZE : exact-nonnegative-integer?

Accumulation blue bits.

value

SDL_GL_ACCUM_ALPHA_SIZE : exact-nonnegative-integer?

Accumulation alpha bits.

25.2.1.3 Multisampling🔗ℹ

value

SDL_GL_MULTISAMPLEBUFFERS : exact-nonnegative-integer?

Number of multisample buffers.

value

SDL_GL_MULTISAMPLESAMPLES : exact-nonnegative-integer?

Number of samples per pixel.

25.2.1.4 Context Settings🔗ℹ

value

SDL_GL_DOUBLEBUFFER : exact-nonnegative-integer?

Enable double buffering.

value

SDL_GL_STEREO : exact-nonnegative-integer?

Enable stereo rendering.

value

SDL_GL_ACCELERATED_VISUAL : exact-nonnegative-integer?

Require hardware acceleration.

value

SDL_GL_RETAINED_BACKING : exact-nonnegative-integer?

Retain buffer contents.

value

SDL_GL_FRAMEBUFFER_SRGB_CAPABLE : exact-nonnegative-integer?

sRGB framebuffer support.

value

SDL_GL_FLOATBUFFERS : exact-nonnegative-integer?

Floating-point buffers.

25.2.1.5 Context Version and Profile🔗ℹ

value

SDL_GL_CONTEXT_MAJOR_VERSION : exact-nonnegative-integer?

OpenGL major version.

value

SDL_GL_CONTEXT_MINOR_VERSION : exact-nonnegative-integer?

OpenGL minor version.

value

SDL_GL_CONTEXT_PROFILE_MASK : exact-nonnegative-integer?

Context profile.

value

SDL_GL_CONTEXT_FLAGS : exact-nonnegative-integer?

Context flags.

25.2.1.6 Context Profiles🔗ℹ

value

SDL_GL_CONTEXT_PROFILE_CORE : exact-nonnegative-integer?

Core profile (no deprecated features).

value

SDL_GL_CONTEXT_PROFILE_COMPATIBILITY

 : exact-nonnegative-integer?
Compatibility profile.

value

SDL_GL_CONTEXT_PROFILE_ES : exact-nonnegative-integer?

OpenGL ES profile.

25.2.1.7 Context Flags🔗ℹ

value

SDL_GL_CONTEXT_DEBUG_FLAG : exact-nonnegative-integer?

Debug context.

value

SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG

 : exact-nonnegative-integer?
Forward compatible.

value

SDL_GL_CONTEXT_ROBUST_ACCESS_FLAG : exact-nonnegative-integer?

Robust access.

value

SDL_GL_CONTEXT_RESET_ISOLATION_FLAG : exact-nonnegative-integer?

Reset isolation.

25.2.1.8 Other🔗ℹ

value

SDL_GL_SHARE_WITH_CURRENT_CONTEXT : exact-nonnegative-integer?

Share with current context.

value

SDL_GL_CONTEXT_RELEASE_BEHAVIOR : exact-nonnegative-integer?

Release behavior.

value

SDL_GL_CONTEXT_RESET_NOTIFICATION : exact-nonnegative-integer?

Reset notification.

value

SDL_GL_CONTEXT_NO_ERROR : exact-nonnegative-integer?

No error context.

value

SDL_GL_EGL_PLATFORM : exact-nonnegative-integer?

EGL platform selection.

25.3 Swap Interval (VSync)🔗ℹ

procedure

(gl-set-swap-interval! interval) → void?

  interval : exact-integer?
Sets the swap interval for the current context.

  • 0 — Immediate (no vsync)

  • 1 — VSync (wait for vertical retrace)

  • -1 — Adaptive vsync (vsync if possible, else immediate)

;; Enable vsync
(gl-set-swap-interval! 1)
 
;; Disable vsync for maximum framerate
(gl-set-swap-interval! 0)

procedure

(gl-get-swap-interval) → exact-integer?

Gets the current swap interval.

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