DOKK / manpages / debian 10 / allegro5-doc / al_draw_polyline.3alleg5.en
al_draw_polyline(3alleg5) al_draw_polyline(3alleg5)

al_draw_polyline - Allegro 5 API

#include <allegro5/allegro_primitives.h>
void al_draw_polyline(const float* vertices, int vertex_stride,
   int vertex_count, int join_style, int cap_style,
   ALLEGRO_COLOR color, float thickness, float miter_limit)

Draw a series of line segments.

•
vertices - Interleaved array of (x, y) vertex coordinates
•
vertex_stride - the number of bytes between pairs of vertices (the stride)
•
vertex_count - Number of vertices in the array
•
join_style - Member of ALLEGRO_LINE_JOIN(3alleg5) specifying how to render the joins between line segments
•
cap_style - Member of ALLEGRO_LINE_CAP(3alleg5) specifying how to render the end caps
•
color - Color of the line
•
thickness - Thickness of the line, pass <= 0 to draw hairline lines
•
miter_limit - Parameter for miter join style

The stride is normally 2 * sizeof(float) but may be more if the vertex coordinates are in an array of some structure type, e.g.

struct VertexInfo {
   float x;
   float y;
   int id;
};
void my_draw(struct VertexInfo verts[], int vertex_count, ALLEGRO_COLOR c)
{
   al_draw_polyline((float *)verts, sizeof(VertexInfo), vertex_count,
      ALLEGRO_LINE_JOIN_NONE, ALLEGRO_LINE_CAP_NONE, c, 1.0, 1.0);
}

The stride may also be negative if the vertices are stored in reverse order.

5.1.0

al_draw_polygon(3alleg5), ALLEGRO_LINE_JOIN(3alleg5), ALLEGRO_LINE_CAP(3alleg5)

Allegro reference manual