NAME

       al_draw_soft_triangle - Allegro 5 API

SYNOPSIS

              #include <allegro5/allegro_primitives.h>

              void al_draw_soft_triangle(
                 ALLEGRO_VERTEX* v1, ALLEGRO_VERTEX* v2, ALLEGRO_VERTEX* v3, uintptr_t state,
                 void (*init)(uintptr_t, ALLEGRO_VERTEX*, ALLEGRO_VERTEX*, ALLEGRO_VERTEX*),
                 void (*first)(uintptr_t, int, int, int, int),
                 void (*step)(uintptr_t, int),
                 void (*draw)(uintptr_t, int, int, int))

DESCRIPTION

       Draws  a  triangle  using  the software rasterizer and user supplied pixel functions.  For
       help in understanding what these functions do,  see  the  implementation  of  the  various
       shading  routines in addons/primitives/tri_soft.c.  The triangle is drawn in two segments,
       from top to bottom.  The segments are deliniated by the vertically middle  vertex  of  the
       triangle.   One  of  the  two  segments  may  be  absent  if two vertices are horizontally
       collinear.

       Parameters:

       • v1, v2, v3 - The three vertices of the triangle

       • state - A pointer to a user supplied struct, this struct will be passed to all the pixel
         functions

       • init  -  Called once per call before any drawing is done.  The three points passed to it
         may be altered by clipping.

       • first - Called twice per call, once per triangle segment.  It is  passed  4  parameters,
         the first two are the coordinates of the initial pixel drawn in the segment.  The second
         two are the left minor and the left major steps, respectively.  They represent the sizes
         of two steps taken by the rasterizer as it walks on the left side of the triangle.  From
         then on, each step will either be classified as a minor or a major  step,  corresponding
         to the above values.

       • step  - Called once per scanline.  The last parameter is set to 1 if the step is a minor
         step, and 0 if it is a major step.

       • draw - Called once per scanline.  The function is expected to draw the scanline starting
         with  a  point  specified  by the first two parameters (corresponding to x and y values)
         going to the right until it reaches the value of the third parameter (the x value of the
         end point).  All coordinates are inclusive.

SEE ALSO

       al_draw_triangle(3alleg5)