OpenGL Core Profile transition and hardware-specific context creation failures

Dynamic Version Negotiation and GLSL Compatibility

To negotiate the highest possible OpenGL version without causing failures on macOS or other restrictive drivers, you must implement a fallback loop. Because requesting a version higher than the hardware supports results in an immediate context creation failure rather than a downgraded version, the application must attempt to create the context starting from the target version and stepping down to a baseline (typically 3.3 for Core Profile).

Negotiation Strategy for macOS and Cross-Platform Support

On macOS, any version 3.2 or higher requires the Core Profile and the GLFW_OPENGL_FORWARD_COMPAT hint. To handle this dynamically:

1. Define a list of supported version pairs (e.g., 4.6, 4.5, 4.1, 3.3).
2. Iterate through this list, setting GLFW_CONTEXT_VERSION_MAJOR and MINOR for each.
3. Set GLFW_OPENGL_PROFILE to GLFW_OPENGL_CORE_PROFILE.
4. Set GLFW_OPENGL_FORWARD_COMPAT to GL_TRUE (mandatory for macOS Core Profile).
5. Attempt glfwCreateWindow; if it returns NULL, move to the next lower version in the list.

Note: If the application must support legacy hardware that does not support Core Profile, you must attempt a separate loop using GLFW_OPENGL_ANY_PROFILE before falling back to the Core loop.

Handling GLSL Version Mismatches

The standard behavior for handling GLSL mismatches is shader permutation or version-header injection. Since the driver will fail to compile a shader if the #version directive is higher than the supported API level, you cannot rely on a single shader file for all production environments.

• Version Injection: Store shaders without a #version tag and prepend the correct string (e.g., #version 330 core\n) at runtime based on the successfully negotiated OpenGL version.
• Feature Detection: Use glGetString(GL_SHADING_LANGUAGE_VERSION) to verify the maximum GLSL version supported by the driver before loading shaders.
• Fallback Shaders: Provide simplified versions of complex shaders that avoid newer GLSL features (like compute shaders or specific layout qualifiers) for lower-tier hardware.

Verification and Diagnostics

After successful context creation, verify the actual granted version using the following command:

const GLubyte* version = glGetString(GL_VERSION);
printf("OpenGL Version: %s\n", version);

If context creation fails across all versions, please provide the GPU vendor and driver version of the failing production environment, as some Intel integrated drivers have specific requirements for profile selection.