glIsTexture returns GL_TRUE if texture is currently the name of a texture. If texture is zero, or is a non-zero value that is not currently the name of a texture, or if an error occurs, glIsTexture returns GL_FALSE.
GL_INVALID_OPERATION is generated if glIsTexture is executed between the execution of glBegin and the corresponding execution of glEnd.
glBindTexture , glCopyTexImage1D , glCopyTexImage2D , glDeleteTextures , glGenTextures , glGet , glGetTexParameter , glTexImage1D , glTexImage2D , glTexImage3D , glTexParameter