al_draw_soft_triangle(3)al_draw_soft_triangle(3)NAMEal_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/primi‐
tives/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 each segment 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, the 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 parame‐
ters (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 ALSOal_draw_triangle(3)Allegro reference manualal_draw_soft_triangle(3)
