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Examples: OpenGL3+Win32: rework OpenGL initialization to allow Wine compatibility. (#9427, #6577)

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ocornut
2026-07-03 18:57:14 +02:00
parent a977144955
commit 4f1ea369ea
2 changed files with 54 additions and 3 deletions
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56
examples/example_win32_opengl3/main.cpp
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@@ -17,12 +17,13 @@
#include <windows.h>
#include <GL/gl.h>
#include <tchar.h>
#include <stdio.h>
// Data stored per platform window
struct WGL_WindowData { HDC hDC; };
// Data
static HGLRC g_hRC;
static HGLRC g_hRC; // Rendering context
static WGL_WindowData g_MainWindow;
static int g_Width;
static int g_Height;
@@ -208,8 +209,57 @@ bool CreateDeviceWGL(HWND hWnd, WGL_WindowData* data)
::ReleaseDC(hWnd, hDc);
data->hDC = ::GetDC(hWnd);
if (!g_hRC)
g_hRC = wglCreateContext(data->hDC);
if (g_hRC)
return true;
// Create legacy context
HGLRC tempRC = wglCreateContext(data->hDC);
if (!tempRC) { ::ReleaseDC(hWnd, data->hDC); return false; }
if (!wglMakeCurrent(data->hDC, tempRC))
{
wglDeleteContext(tempRC);
::ReleaseDC(hWnd, data->hDC);
return false;
}
// Get context version
GLint major = 0, minor = 0;
glGetIntegerv(0x821B, &major); // GL_MAJOR_VERSION
glGetIntegerv(0x821C, &minor); // GL_MINOR_VERSION
const char* gl_version_str = (const char*)glGetString(GL_VERSION);
if (major == 0 && minor == 0)
sscanf_s(gl_version_str, "%d.%d", &major, &minor); // Query GL_VERSION in desktop GL 2.x, the string will start with "<major>.<minor>"
const GLuint gl_version = (GLuint)(major * 100 + minor * 10);
// Keep temporary context: already OpenGL 3.0+.
g_hRC = tempRC;
//if (gl_version >= 300)
// return true;
typedef HGLRC(WINAPI* PFNWGLCREATECONTEXTATTRIBSARBPROC)(HDC, HGLRC, const int*);
const PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribsARB = (PFNWGLCREATECONTEXTATTRIBSARBPROC)wglGetProcAddress("wglCreateContextAttribsARB");
// GL 3.0
const int attribs[] =
{
0x2091, 3, // WGL_CONTEXT_MAJOR_VERSION_ARB
0x2092, 0, // WGL_CONTEXT_MINOR_VERSION_ARB
0x9126, 0x0001, // WGL_CONTEXT_PROFILE_MASK_ARB, WGL_CONTEXT_CORE_PROFILE_BIT_ARB
0
};
HGLRC newRC = nullptr;
if (wglCreateContextAttribsARB)
newRC = wglCreateContextAttribsARB(data->hDC, 0, attribs);
// If we managed to create 3.0+ context: use that one and destroy the temporary OpenGL 2.x compatibility context.
if (newRC)
{
wglMakeCurrent(nullptr, nullptr);
wglDeleteContext(tempRC);
g_hRC = newRC;
wglMakeCurrent(data->hDC, g_hRC);
}
return true;
}