al_draw_soft_triangle - Allegro 5 API
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#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))
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
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- state - A pointer to a user supplied struct, this struct will be passed to
all the pixel functions
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- 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.