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Backends: OpenGL3: Fixed loader compatibility with GL_VERSION for GL …
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…2.x (#6154, #4445, #3530)

GL_MAJOR_VERSION and GL_MINOR_VERSION are available on GL 3.0 and above.
So we have to parse GL_VERSION under GL 2.x
Reference https://www.khronos.org/opengl/wiki/OpenGL_Context#Context_information_queries
Regressed since 459de65
See #3530
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grauw authored and ocornut committed Feb 14, 2023
1 parent fa0852f commit b0c1816
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Showing 2 changed files with 10 additions and 3 deletions.
10 changes: 8 additions & 2 deletions backends/imgui_impl_opengl3_loader.h
Original file line number Diff line number Diff line change
Expand Up @@ -685,7 +685,13 @@ static int parse_version(void)
return GL3W_ERROR_INIT;
glGetIntegerv(GL_MAJOR_VERSION, &version.major);
glGetIntegerv(GL_MINOR_VERSION, &version.minor);
if (version.major < 3)
if (version.major == 0 && version.minor == 0)
{
// Query GL_VERSION in desktop GL 2.x, the string will start with "<major>.<minor>"
const char* gl_version = (const char*)glGetString(GL_VERSION);
sscanf(gl_version, "%d.%d", &version.major, &version.minor);
}
if (version.major < 2)
return GL3W_ERROR_OPENGL_VERSION;
return GL3W_OK;
}
Expand All @@ -709,7 +715,7 @@ int imgl3wInit2(GL3WGetProcAddressProc proc)

int imgl3wIsSupported(int major, int minor)
{
if (major < 3)
if (major < 2)
return 0;
if (version.major == major)
return version.minor >= minor;
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3 changes: 2 additions & 1 deletion docs/CHANGELOG.txt
Original file line number Diff line number Diff line change
Expand Up @@ -116,7 +116,8 @@ All changes:
- Backends: GLFW: Added ImGui_ImplGlfw_SetCallbacksChainForAllWindows() to instruct backend
to chain callbacks even for secondary viewports/windows. User callbacks may need to test
the 'window' parameter. (#6142)
- Backends: WebGPU: Fix building for latest WebGPU specs (remove implicit layout generation).
- Backends: OpenGL3: Fixed GL loader compatibility with 2.x profiles. (#6154, #4445, #3530) [@grauw]
- Backends: WebGPU: Fixed building for latest WebGPU specs (remove implicit layout generation).
(#6117, #4116, #3632) [@tonygrue, @bfierz]
- Examples: refactored SDL2+GL and GLFW+GL examples to compile with Emscripten.
(#2492, #2494, #3699, #3705) [@ocornut, @nicolasnoble]
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