module PNG2Polygon

[gcmartijnParticipant]

Reserved topic for module

[Mark SiblyKeymaster]

Sounds interesting!

[gcmartijnParticipant]

I ‘uploaded’ the module PNG2Polygon and made a screenshot to make it easy to understand what is does. (check this image first, and then read below)

I use it in a situation like this.
– a number of high quality transparent PNG files that need a check for a collision and/or user mouse

First I use a PNG2Polygon inside a editor to convert all the PNG files to the smallest simplified x and y coordinates and save them in a json file. something like this:
circle.png : [x,y,x,y,x,y]
star.png : [x,y,x,y]

Then where I need the collision in game I load the coordinates (verts) once.
And use it something like this:

Monkey

Local CollisionType:Int = PolyCollision(verts,Mouse.X,Mouse.Y) If CollisionType=0 Then ' no collision Elseif CollisionType=1 Then ' line collision Elseif CollisionType=2 Then ' point inside End

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Local CollisionType:Int = PolyCollision(verts,Mouse.X,Mouse.Y) If CollisionType=0 Then ' no collision Elseif CollisionType=1 Then ' line collision Elseif CollisionType=2 Then ' point inside End

As you can see, the simplified coordinates are way less x,y points then the total png2polygon.outline points.
So there is less CPU/GPU needed to check for a collision.

There are situations that simplifying not work in combination with a line collision.
For example the figure below the circle.
In that situation the PolyCollision() can’t detect line collision, but it can detect point inside collision
If you want a perfect line collision using that figure, then you need the full png2polygon.outline

This script uses
https://en.wikipedia.org/wiki/Moore_neighborhood
https://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm

Inside the module there is a [test] directory with examples.

Attachments:

1. 

   png2polygon.png
   

[gcmartijnParticipant]

The module is now online inside Ted2.

[Richard BetsonParticipant]

I will check this out. This seems like the kind of solution I’m looking for in constructing polygons for in game collision. Neat.

[HezkoreParticipant]

I totally missed this, but it’s awesome!

Is there a way to get some sort of data I could construct 3D shapes from?
I just want a flat “3D mesh”/surface using the simplified outline this module produces.

[EthernautParticipant]

Hezkore, would this work for you? Needs Import/Using mojo3d. The “length” parameter is how deep the extrusion is. It extrudes in both directions (positive/negative Z axis), but this can be easily changed.

(Untested outside the project I made this for).

Monkey

Function LineExtrude:Mesh( points:Vertex2f[], length:Float, closedCurve:Bool = False, flip:Bool = False ) Local front:= New Stack<Vertex3f> Local back:= New Stack<Vertex3f> Local indices := New Stack<UInt> Local vertices := New Stack<Vertex3f> Local totalVerts := points.Length Local sides:= totalVerts If Not closedCurve sides -= 1 If totalVerts = 2 Then sides = 1 'Prevents two overlapping planes if line only has two vertices Local n := 0.0 For Local v := Eachin points Local u := n/ Float(sides) front.Push( New Vertex3f(v.position.X, v.position.Y, -length/2, u, 0.0) ) back.Push( New Vertex3f(v.position.X, v.position.Y, +length/2, u, 1.0) ) n += 1.0 Next For Local i0 := 0 Until sides Local i1 := i0 + 1 If i1 > totalVerts - 1 Then i1 = 0 indices.Push( UInt(i0) ) indices.Push( UInt(i0 + totalVerts) ) indices.Push( UInt(i1) ) indices.Push( UInt(i0 + totalVerts) ) indices.Push( UInt(i1 + totalVerts) ) indices.Push( UInt(i1) ) Next For Local v := Eachin front vertices.Push( v ) Next For Local v := Eachin back vertices.Push( v ) Next Local mesh := New Mesh( vertices.ToArray(), indices.ToArray() ) mesh.UpdateTangents() mesh.UpdateNormals() If flip Then mesh.FlipTriangles() mesh.Compact() Return mesh End

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Function LineExtrude:Mesh( points:Vertex2f[], length:Float, closedCurve:Bool = False, flip:Bool = False )   Local front:= New Stack<Vertex3f> Local back:= New Stack<Vertex3f> Local indices := New Stack<UInt> Local vertices := New Stack<Vertex3f> Local totalVerts := points.Length Local sides:= totalVerts If Not closedCurve sides -= 1 If totalVerts = 2 Then sides = 1 'Prevents two overlapping planes if line only has two vertices Local n := 0.0 For Local v := Eachin points Local u := n/ Float(sides) front.Push( New Vertex3f(v.position.X, v.position.Y, -length/2, u, 0.0) ) back.Push( New Vertex3f(v.position.X, v.position.Y, +length/2, u, 1.0) ) n += 1.0 Next For Local i0 := 0 Until sides Local i1 := i0 + 1 If i1 > totalVerts - 1 Then i1 = 0 indices.Push( UInt(i0) ) indices.Push( UInt(i0 + totalVerts) ) indices.Push( UInt(i1) ) indices.Push( UInt(i0 + totalVerts) ) indices.Push( UInt(i1 + totalVerts) ) indices.Push( UInt(i1) ) Next For Local v := Eachin front vertices.Push( v ) Next For Local v := Eachin back vertices.Push( v ) Next Local mesh := New Mesh( vertices.ToArray(), indices.ToArray() ) mesh.UpdateTangents() mesh.UpdateNormals() If flip Then mesh.FlipTriangles() mesh.Compact() Return mesh End

I’m using it to generate 3d colliders for a “2.5D” game.

[edit] Just realized this doesn’t generate front and back caps, only the side walls. It would need a good mesh triangulation algorithm to do that well.

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