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gui-native-win-opengl.md

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Win32 OpenGL Bootstrap (gui-native-win-opengl)

Overview

gui-native-win-opengl initializes an OpenGL 2D rendering layer for a Win32 window via wgl. It selects a compatible pixel format using a standard PIXELFORMATDESCRIPTOR, creates a context with wglCreateContext, and verifies it with wglMakeCurrent.

This module is part of the native Windows GUI backend and is not intended for direct use in application code. OpenGL layer selection is controlled by the GUI.createWindow options object.

Import

opengl := import('gui-native-win-opengl')
{ initOpenGL2DLayer: initOpenGL2DLayer } := import('gui-native-win-opengl')

Constants

Constant Value Description
PFD_DRAW_TO_WINDOW 4 Pixel format flag: render to window DC
PFD_SUPPORT_OPENGL 32 Pixel format flag: support OpenGL
PFD_DOUBLEBUFFER 1 Pixel format flag: double-buffered

Functions

initOpenGL2DLayer(window)

Attempts to initialize an OpenGL context on window. The sequence is:

  1. Acquire the window DC with GetDC.
  2. Build a 40-byte PIXELFORMATDESCRIPTOR requesting 32-bit RGBA with 24-bit depth and 8-bit stencil, double-buffered, drawn to a window.
  3. Select a pixel format with ChoosePixelFormat / SetPixelFormat.
  4. Create the context with wglCreateContext and verify it with wglMakeCurrent.
  5. Release the resources and return the context handle.

Returns { type: :ok, context, pixelFormat, makeCurrentResult } on success, or { type: :error, error: string, ... } on failure.

result := initOpenGL2DLayer(window)
if result.type = :ok {
    true -> {
        window.openglContext <- result.context
        window.openglPixelFormat <- result.pixelFormat
    }
    _ -> printf('OpenGL init failed: {{0}}', result.error)
}

Note: The context is released (wglMakeCurrent(0,0)) immediately after creation. Callers are responsible for making it current before issuing draw calls.