HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 281

M glMap2 Each control point is two floating-point values representing the s and t texture coordinates. Internal glTexCoord2 commands are generated when the map is evaluated but the current texture coordinates are not updated with the value of these glTexCoord commands. GL_MAP2_TEXTURE_COORD_3 Each control point is three floating-point values representing the s, t, and r texture coordinates. Internal glTexCoord3 commands are generated when the map is evaluated but the current texture coordinates are not updated with the value of these glTexCoord commands. GL_MAP2_TEXTURE_COORD_4 Each control point is four floating-point values representing the s, t, r, and q texture coordinates. Internal glTexCoord4 commands are generated when the map is evaluated but the current texture coordinates are not updated with the value of these glTexCoord commands. ustride, uorder, vstride, vorder, and points define the array addressing for accessing the control points. points is the location of the first control point, which occupies one, two, three, or four contiguous memory locations, depending on which map is being defined. There are uorder× vorder control points in the array. ustride specifies how many float or double locations are skipped to advance the internal memory pointer from control point Rij to control point R(i+1)j. vstride specifies how many float or double locations are skipped to advance the internal memory pointer from control point Rij to control point Ri(j+1). Notes As is the case with all GL commands that accept pointers to data, it is as if the contents of points were copied by glMap2 before glMap2 returns. Changes to the contents of points have no effect after glMap2 is called. Initially, GL_AUTO_NORMAL is enabled. If GL_AUTO_NORMAL is enabled, normal vectors are generated when either GL_MAP2_VERTEX_3 or GL_MAP2_VERTEX_4 is used to generate vertices. Errors • GL_INVALID_ENUM is generated if target is not an accepted value. • GL_INVALID_VALUE is generated if u1 is equal to u2, or if v1 is equal to v2. • GL_INVALID_VALUE is generated if either ustride or vstride is less than the number of values in a control point. • GL_INVALID_VALUE is generated if either uorder or vorder is less than 1 or greater than the return value of GL_MAX_EVAL_ORDER. • GL_INVALID_OPERATION is generated if glMap2 is executed between the execution of glBegin and the corresponding execution of glEnd. Chapter 11 281