GL_OES_sample_shading
https://www.khronos.org/registry/OpenGL/extensions/OES/OES_sample_shading.txt
GL_OES_sample_shading

	GL_SAMPLE_SHADING_OES 0x8C36
	GL_MIN_SAMPLE_SHADING_VALUE_OES 0x8C37
	void glMinSampleShadingOES (GLfloat value)