Ok, so I have a polygon (simple but concave) that I'm trying to cut into triangles to make it collide with an other polygon.
I knew my polygone was concave, so i decided to use LibGDX EarClippingTriangulator to manage to cut it into triangles.
So, with this code, I get my triangles vertices :
public void triangulate()
{
Vector<float[]> trianglesVertices = new Vector<float[]>();
ShortArray pointsCoords = new ShortArray();
EarClippingTriangulator triangulator = new EarClippingTriangulator();
// Cut in triangles
pointsCoords = triangulator.computeTriangles(this.getTransformedVertices());
// Make triangles
for (int i = 0; i < pointsCoords.size / 6; i++)
{
trianglesVertices.add(new float[] {
pointsCoords.get(i), pointsCoords.get(i+1),
pointsCoords.get(i+2), pointsCoords.get(i+3),
pointsCoords.get(i+4), pointsCoords.get(i+5),
});
Polygon triangle = new Polygon(trianglesVertices.get(i));
triangles.add(triangle);
}
System.out.printf("Triangulation made %d triangles.\n", pointsCoords.size / 6);
}
But when i try to draw thoses triangles I just made, they just stack in the 0,0 coord.. And, is it normal that all triangles seems almost the sames, I mean they all got the same orientation ?
I didn't found so much info about this trangulation use for libgdx Can you help ?
(Sorry for my english i'm french, and sorry for no pictures, i'm too young here)
EDIT: This is my polygon (in CCW)
hitbox.setVertices(new float[]{
this.getX() + 13, this.getY() - 60,
this.getX() + 16, this.getY() - 74,
this.getX() + 39, this.getY() - 74,
this.getX() + 45, this.getY() - 105,
this.getX() + 81, this.getY() - 105,
this.getX() + 88, this.getY() - 74,
this.getX() + 108, this.getY() - 74,
this.getX() + 114, this.getY() - 61,
this.getX() + 106, this.getY() - 30, // Top right
this.getX() + 101, this.getY() - 29,
this.getX() + 101, this.getY() - 57,
this.getX() + 83, this.getY() - 62,
this.getX() + 75, this.getY() - 50,
this.getX() + 65, this.getY() - 4, // Top mid
this.getX() + 62, this.getY() - 4, // Top mid
this.getX() + 52, this.getY() - 50,
this.getX() + 44, this.getY() - 62,
this.getX() + 25, this.getY() - 56,
this.getX() + 25, this.getY() - 30,
this.getX() + 19, this.getY() - 30, // Top left
});
EDIT2: Now i got enough point to show you the polygon here it is
The problem is with your loop:
// Make triangles
for (int i = 0; i < pointsCoords.size / 6; i++)
{
trianglesVertices.add(new float[] {
pointsCoords.get(i), pointsCoords.get(i+1),
pointsCoords.get(i+2), pointsCoords.get(i+3),
pointsCoords.get(i+4), pointsCoords.get(i+5),
});
Polygon triangle = new Polygon(trianglesVertices.get(i));
triangles.add(triangle);
}
First triangle will have correct coordinates, but second one will will use 1, 2, 3, 4, 5, 6 elements of pointsCoords
that doesn't make any sence. You should multiply i
by 6 inside loop to take offset into account:
pointsCoords.get(i*6), pointsCoords.get(i*6 + 1),
pointsCoords.get(i*6 + 2), pointsCoords.get(i*6 + 3),
pointsCoords.get(i*6 + 4), pointsCoords.get(i*6 + 5),