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glDrawRangeElements (3)

>> glDrawRangeElements (3) ( Разные man: Библиотечные вызовы )

NAME

glDrawRangeElements - render primitives from array data

C SPECIFICATION

void glDrawRangeElements( GLenum mode,


                            GLuint start,
                            GLuint end,
                            GLsizei count,
                            GLenum type,
                            const GLvoid *indices )

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PARAMETERS

mode: Specifies what kind of primitives to render. Symbolic constants GL_POINTS, GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES, GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, GL_TRIANGLES, GL_QUAD_STRIP, GL_QUADS, and GL_POLYGON are accepted.
start: Specifies the minimum array index contained in indices.
end: Specifies the maximum array index contained in indices.
count: Specifies the number of elements to be rendered.
type: Specifies the type of the values in count. Must be one of GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT, or GL_UNSIGNED_INT.
indices: Specifies a pointer to the location where the indices are stored.

DESCRIPTION

glDrawRangeElements is a restricted form of glDrawElements. mode, start, end, and count match the corresponding arguments to glDrawElements, with the additional constraint that all values in the arrays count must lie between start and end, inclusive. Implementations denote recommended maximum amounts of vertex and
index data, which may be queried by calling glGet with argument GL_MAX_ELEMENTS_VERTICES and GL_MAX_ELEMENTS_INDICES. If $"end" ~-~ "start" ~+~ 1$ is greater than the value of GL_MAX_ELEMENTS_VERTICES, or if count is greater than the value of GL_MAX_ELEMENTS_INDICES, then the call may operate at reduced performance. There is no requirement that all vertices in the range [start, end] be referenced. However, the implementation may partially process unused vertices, reducing performance from what could be achieved with an optimal index set. When glDrawRangeElements is called, it uses start sequential elements from an enabled array, starting at count to construct a sequence of geometric primitives. mode specifies what kind of primitives are constructed, and how the array elements construct these primitives. If more than one array is enabled, each is used. If GL_VERTEX_ARRAY is not enabled, no geometric primitives are constructed. Vertex attributes that are modified by glDrawRangeElements have an unspecified value after glDrawRangeElements returns. For example, if GL_COLOR_ARRAY is enabled, the value of the current color is undefined after glDrawRangeElements executes. Attributes that aren't modified maintain their previous values.

NOTES

glDrawRangeElements is available only if the GL version is 1.2 or greater. glDrawRangeElements is included in display lists. If glDrawRangeElements is entered into a display list, the necessary array data (determined by the array pointers and enables) is also entered into the display list. Because the array pointers and enables are client-side state, their values affect display lists when the lists are created, not when the lists are executed.

ERRORS

It is an error for indices to lie outside the range [start, end], but implementations may not check for this situation. Such indices cause implementation-dependent behavior. GL_INVALID_ENUM is generated if mode is not an accepted value. GL_INVALID_VALUE is generated if count is negative. GL_INVALID_VALUE is generated if end $<$ start. GL_INVALID_OPERATION is generated if glDrawRangeElements is executed between the execution of glBegin and the corresponding glEnd.