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OpenGL Command Syntax

OpenGL commands use the prefix gl and initial capital letters for each word making up the command name (glClearColor(), for example). Similarly, OpenGL defined constants begin with GL_, use all capital letters, and use underscores to separate words (like GL_COLOR_BUFFER_BIT).

Some letters appended to some command names (the 3f in glColor3f(), for example).
The 3 part of the suffix indicates that three arguments are given.
The f part of the suffix indicates that the arguments are floating-point numbers.


Command Suffixes and Argument Data: Types
Suffix Data Type Typical Corresponding C-Language Type OpenGL Type Definition
b 8-bit integer signed char GLbyte
s 16-bit integer short GLshort
i 32-bit integer long GLint, GLsizei
f 32-bit floating-point float GLfloat, GLclampf
d 64-bit floating-point double GLdouble, GLclampd
ub 8-bit unsigned integer unsigned char GLubyte, GLboolean
us 16-bit unsigned integer unsigned short GLushort
ui 32-bit unsigned integer unsigned long GLuint, GLenum, GLbitfield

 

Thus, the two commands 

glVertex2i(1, 3);
glVertex2f(1.0, 3.0);
are equivalent, except that the first specifies the vertex's coordinates as 32-bit integers and the second specifies them as single-precision floating-point numbers.

Some OpenGL commands can take a final letter v, which indicates that the command takes a pointer to a vector (or array) of values rather than a series of individual arguments. Many commands have both vector and nonvector versions: 

glColor3f(1.0, 0.0, 0.0);

float color_array[] = {1.0, 0.0, 0.0};
glColor3fv(color_array);
Usually OpenGL commands are referred to by their base names only, and an asterisk is included to indicate that there may be more to the command name, for example, glColor*().

voidglColor3{b s i f d ub us ui} (TYPEr, TYPEg, TYPEb);
void glColor4{b s i f d ub us ui} (TYPEr, TYPEg, TYPEb, TYPEa);
void glColor3{b s i f d ub us ui}v (const TYPE*v);
void glColor4{b s i f d ub us ui}v (const TYPE*v);