glIsEnabled − test whether a capability is enabled
GLboolean glIsEnabled( GLenum cap )
Specifies a symbolic constant indicating a GL capability.
glIsEnabled returns GL_TRUE if cap is an enabled capability and returns GL_FALSE otherwise. Initially all capabilities except GL_DITHER are disabled; GL_DITHER is initially enabled.
The following capabilities are accepted for cap:
If an error is generated, glIsEnabled returns 0.
GL_COLOR_LOGIC_OP, GL_COLOR_ARRAY, GL_EDGE_FLAG_ARRAY, GL_INDEX_ARRAY, GL_INDEX_LOGIC_OP, GL_NORMAL_ARRAY, GL_POLYGON_OFFSET_FILL, GL_POLYGON_OFFSET_LINE, GL_POLYGON_OFFSET_POINT, GL_TEXTURE_COORD_ARRAY, and GL_VERTEX_ARRAY are available only if the GL version is 1.1 or greater
GL_RESCALE_NORMAL, and GL_TEXTURE_3D are available only if the GL version is 1.2 or greater.
GL_COLOR_TABLE, GL_CONVOLUTION_1D, GL_CONVOLUTION_2D, GL_HISTOGRAM, GL_MINMAX, GL_POST_COLOR_MATRIX_COLOR_TABLE, GL_POST_CONVOLUTION_COLOR_TABLE, and GL_SEPARABLE_2D are available only if GL_ARB_imaging is returned when glGet is called with GL_EXTENSIONS.
When the GL_ARB_multitexture extension is supported, the following parameters return the associated value for the active texture unit. GL_TEXTURE_1D, GL_TEXTURE_BINDING_1D, GL_TEXTURE_2D, GL_TEXTURE_BINDING_2D, GL_TEXTURE_3D, GL_TEXTURE_BINDING_3D, GL_TEXTURE_GEN_S, GL_TEXTURE_GEN_T, GL_TEXTURE_GEN_R, GL_TEXTURE_GEN_Q, GL_TEXTURE_MATRIX, and GL_TEXTURE_STACK_DEPTH. Likewise, the following parameters return the associated value for the active client texture unit: GL_TEXTURE_COORD_ARRAY, GL_TEXTURE_COORD_ARRAY_SIZE, GL_TEXTURE_COORD_ARRAY_STRIDE, GL_TEXTURE_COORD_ARRAY_TYPE.
GL_INVALID_ENUM is generated if cap is not an accepted value.
GL_INVALID_OPERATION is generated if glIsEnabled is executed between the execution of glBegin and the corresponding execution of glEnd.
glEnable(3G), glEnableClientState(3G), glGet(3G)
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