3.7 KiB
_glDrawElements: render primitives from array data
Syntax
SUB _glDrawElements (BYVAL mode AS _UNSIGNED LONG, BYVAL count AS LONG, BYVAL type AS _UNSIGNED LONG, indices AS _OFFSET) void _glDrawElements(GLenum mode, GLsizei count, GLenum type, const GLvoid * indices);
; mode
Specifies what kind of primitives to render. Symbolic constants _GL_POINTS, _GL_LINE_STRIP, _GL_LINE_LOOP, _GL_LINES, _GL_LINE_STRIP_ADJACENCY, _GL_LINES_ADJACENCY, _GL_TRIANGLE_STRIP, _GL_TRIANGLE_FAN, _GL_TRIANGLES, _GL_TRIANGLE_STRIP_ADJACENCY, _GL_TRIANGLES_ADJACENCY and _GL_PATCHES are accepted. ; count Specifies the number of elements to be rendered. ; 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
_glDrawElements specifies multiple geometric primitives with very few subroutine calls. Instead of calling a GL function to pass each individual vertex, normal, texture coordinate, edge flag, or color, you can prespecify separate arrays of vertices, normals, and so on, and use them to construct a sequence of primitives with a single call to _glDrawElements.
When _glDrawElements is called, it uses count sequential elements from an enabled array, starting at indices (interpreted as a byte 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.
Vertex attributes that are modified by _glDrawElements have an unspecified value after _glDrawElements returns. Attributes that aren't modified maintain their previous values.
Notes
_GL_LINE_STRIP_ADJACENCY, _GL_LINES_ADJACENCY, _GL_TRIANGLE_STRIP_ADJACENCY and _GL_TRIANGLES_ADJACENCY are available only if the GL version is 3.2 or greater.
Error(s)
_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 a geometry shader is active and mode is incompatible with the input primitive type of the geometry shader in the currently installed program object.
_GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to an enabled array or the element array and the buffer object's data store is currently mapped.
See Also
_GL _glBindVertexArray, _glDrawArrays, _glDrawElementsBaseVertex, _glDrawElementsIndirect, _glDrawElementsInstanced, _glDrawElementsInstancedBaseInstance, _glDrawElementsInstancedBaseVertex, _glDrawElementsInstancedBaseVertexBaseInstance, _glDrawRangeElements, _glDrawRangeElementsBaseVertex, _glMultiDrawElements, _glMultiDrawElementsBaseVertex, _glMultiDrawElementsIndirect