OpenGL 4.2 (Compatibility Profile) - April 27, 2012

2.22. FLATSHADING 210
Primitive type of polygon i First vertex convention Last vertex convention
point i i
independent line 2i − 1 2i
line loop i i + 1, if i < n
1, if i = n
line strip i i + 1
independent triangle 3i − 2 3i
triangle strip i i + 2
triangle fan i + 1 i + 2
independent quad 4i − 3 4i 1
4i 4i 2
quad strip 2i − 1 2i + 2 1
2i + 2 2i + 2 2
single polygon (i = 1) 1 1
line adjacency 4i − 2 4i − 1
line strip adjacency i + 1 i + 2
triangle adjacency 6i − 5 6i − 1
triangle strip adjacency 2i − 1 2i + 3
Table 2.18: Provoking vertex selection. The vertex colors and/or output values
used for flatshading the ith primitive generated by the indicated Begin / End type
are derived from the corresponding values of the vertex whose index is shown in
the table. Vertices are numbered 1 through n, where n is the number of vertices
between the Begin / End pair.
1 If the value of QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION is TRUE.
2 If the value of QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION is FALSE.
flatshaded colors and outputs, as shown in table 2.18
The provoking vertex behavior of quad primitives is implementation dependent,
and may be determined by calling GetBooleanv with the symbolic constant
QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION. A return value of TRUE indicates
that the provoking vertex mode is respected for quad primitives, while a
return value of FALSE indicates that the implementation always behave as though
the provoking vertex mode were LAST_VERTEX_CONVENTION.
Flatshading of colors in fixed-function vertex processing, and of the builtin
outputs gl_FrontColor, gl_BackColor, gl_FrontSecondaryColor and
gl_BackSecondaryColor when a vertex shader is active, is controlled with the
command
OpenGL 4.2 (Compatibility Profile) - April 27, 2012