NAME

       dtk_create_complex_shape  -  Creates  or  modify  a  shape  to display custom and evolving
       content

SYNOPSIS

       #include <drawtk.h>

       dtk_hshape dtk_create_complex_shape(dtk_hshape shp,
                           unsigned int nvert, const float *vertpos,
                           const float *vertcolor, const float *texcoords,
                           unsigned int nind, const unsigned int *ind,
                           unsigned int type, dtk_htex tex);

DESCRIPTION

       dtk_create_complex_shape() creates a shape  displaying  a  complex,  custom  and  possibly
       evolving  content described by vertex attribute buffers (vertpos, vertcolor and texcoords)
       and an array ind containing the indices of vertices whose order describes how  to  connect
       the  vertices altogether in order to form primitives (controlled by type). tex can be used
       to specify a texture to be mapped onto the shape.

       vertpos should point to an array of nvert pairs  of  float  values  corresponding  of  the
       position  (x,y)  of  each vertex. vertcolor should point to an array of nvert quatuples of
       float values corresponding of the color (R,G,B,A) of each vertex. texcoords can be  either
       NULL  or can point to an array of nvert pairs of float values corresponding to the texture
       coordinates (u,v) of the vertex. If texcoords is NULL, no texture will be used even if tex
       is not null.

       ind  should  point  to  an  array  of nind indices of the vertices in the vertex attribute
       buffers. This list of indices determines how the vertices form the primitives and  depends
       on type zhich can take one the following value (See OpenGL manual to have detail):

       DTK_TRIANGLE_STRIP
              The   first  three  vertices  defines  the  first  triangle  (and  their  order  is
              significant). Each subsequent vertex defines a new triangle using that point  along
              with two vertices from the previous triangle.

       DTK_TRIANGLE_FAN
              A triangle fan is the same as a triangle strip with one exception: the first vertex
              of the list is always the first vertex of each triangle.

       DTK_TRIANGLES
              Separate triangles are specified. Every 3 indices defines in the order a  triangle.
              If nind is not a multiple of 3, the excedent 1 or 2 indices are ignored.

       DTK_LINE_STRIP
              A  series of one or more connected line segments is specified by enclosing a series
              of two or more endpoints. In this case, the ith index specifies the  end  point  of
              the i-1st segment and the start point of the ith segment.

       DTK_LINES
              Individual  line  segments,  each  specified by a pair of vertices. If nind is odd,
              then the last index is ignored.

       shp can be used to modify a previously created shape. If it is non-null, the  handle  will
       be  used  to  modify the shape referenced by shp: no new shape is created and the returned
       value is ensured to be shp in case of  success,  NULL  otherwise.  If  shp  is  NULL,  the
       function will attempt to create a new shape.

       The  arrays  vertpos, vertcolor, texcoords and ind are not copied into internal structures
       of the created shape. This allows one to dynamically  change  any  aspect  of  the  shape.
       However,  in  return it forces to keep the buffers allocated during the whole life time of
       the shape.

RETURN VALUE

       In case of success the function returns the handle to the newly created or modified shape.
       If  the shp argument is non-null, the handle returned is the same value. In case of error,
       NULL is returned.

THREAD SAFETY

       The data contained into the buffers are accessed only during the creation and the draw  of
       the  shape. So if the data is updated in a different thread than the one used for drawing,
       some locking is needed.

SEE ALSO

       dtk_create_shape(3)