glDrawRangeElementsEXT

NAME

glDrawRangeElementsEXT - render primitives from array data

C SPECIFICATION

void glDrawRangeElementsEXT(GLenum mode,
                    GLsizei count,
                    GLuint start,
                    GLuint end,
                    GLenum type,
                    const GLvoid *indices)

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.
count	Specifies the number of elements to be rendered.
start	Specifies the minimum index number that will be accessed.
end	Specifies the maximum index number that will be accessed.
type	Specifies the type of the values in indices. 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

glDrawRangeElementsEXT is a restricted form of glDrawElements. All vertices referenced by indices must lie between start and end inclusive. Not all vertices between start and end must be referenced, however unreferenced vertices may be sent through some of the vertex pipeline before being discarded, reducing performance from what could be achieved by an optimal index set. Index values which lie outside the range will cause implementation-dependent results.

glDrawRangeElementsEXT may also be further constrained to only operate at maximum performance for limited amounts of data. Implementations may advertise recommended maximum amounts of vertex and index data using the GL_MAX_ELEMENTS_VERTICES_EXT and GL_MAX_ELEMENTS_INDICES_EXT constants. If a particular call to glDrawRangeElementsEXT has (end - start + 1) greater than GL_MAX_ELEMENTS_VERTICES_EXT or if count is greater than GL_MAX_ELEMENTS_INDICES, the implementation may be forced to process the data less efficiently than it could have with less data.

An implementation which has no effective limits can advertise the maximum integer value for the two constants. An implementation must always process a glDrawRangeElementsEXT call with valid parameters regardless of the amount of data passed in the call.

The parameters mode, count, type, and indices behave exactly the same as in the function glDrawElements.

NOTES

glDrawRangeElementsEXT is included in display lists. If glDrawRangeElementsEXT 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.

EXTENSIONS

Some routines and constants for this function are part of an extension, not part of the core GL command set. The following extension names must be present in the string returned by glGetString when called with argument GL_EXTENSIONS to use these routines and constants.

GL_EXT_draw_range_elements: glDrawRangeElementsEXT, GL_MAX_ELEMENTS_VERTICES_EXT, and GL_MAX_ELEMENTS_INDICES_EXT are part of the EXT_draw_range_elements extension.

ERRORS

GL_INVALID_ENUM is generated if mode is not an accepted value.

GL_INVALID_VALUE is generated if count is negative.

GL_INVALID_OPERATION is generated if glDrawRangeElementsEXT is executed between the execution of glBegin and the corresponding glEnd.

GL_INVALID_VALUE will be returned if end is less than start.