dtk_create_shape man page
dtk_create_shape — Create and modify custom shape
dtk_hshape dtk_create_shape(dtk_hshape shp,
unsigned int ind_num, const float *vertex_array,
int filled, const float *color);
dtk_create_shape() creates a shape specified by ind_num vertices referenced by vertex_array. In this array, the position parameters (x,y) of each vertex are packed together and the list should ordered, so that the array is filled in the following way: x0,y0,x1,y1,x2,y2,...,xN,yN.
shp, filled and color have the same usage and meaning as for other shape creation function:
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.
filled is set to 0 if the described shape should be a continuous line or a non-null value if the shape is supposed to be filled polygon. In the case of filled polygon request, the last point specified in vertex_array will be connected with the first one.
color should point to a 4 float array containing a normalized RGBA value (i.e. each component is between 0.0 and 1.0).
In case of success these functions return 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.
dtk_create_complex_shape(3), dtk_create_composite_shape(3), dtk_create_string(3), dtk_destroy_shape(3), dtk_setcolor_shape(3).