# How are PShape contours stored?
**URL:** https://discourse.processing.org/t/how-are-pshape-contours-stored/26997
**Category:** Coding Questions
**Created:** [January 12, 2021, 7:12pm UTC](https://discourse.processing.org/t/how-are-pshape-contours-stored/26997 "2021-01-12T19:12:36Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@micycle](https://discourse.processing.org/u/micycle)
#### Post date: [January 12, 2021, 7:12pm UTC](https://discourse.processing.org/t/how-are-pshape-contours-stored/26997/1 "2021-01-12T19:12:36Z")
Take the PShape above. Clearly it must know that the vertices of the inner region are not to be joined with the other vertices of the edge and represent a region that is “cut-out” from the shape. Processing calls such regions [contours](https://processing.org/reference/PShape_beginContour_.html).
**Is there a way to get this info from a PShape?** i.e. which contour group each vertex belongs to?
Now there’s a method `getVertexCodes()` which looked promising but the array it returns has less length than the number of vertices a shape has, so I wonder whether this refers to what I want and whether it’s possible to get this info from it.
---
### Author:  [@behreajj](https://discourse.processing.org/u/behreajj)
#### Post date: [January 12, 2021, 7:45pm UTC](https://discourse.processing.org/t/how-are-pshape-contours-stored/26997/2 "2021-01-12T19:45:02Z")
Hi @micycle ,
The vertex codes will not match the number of vertices. For a cubic Bezier vertex, there will be 3 pairs (6 floats) in vertices per command; for a quadratic Bezier vertex 2 pairs (4 floats) in vertices per command. That’s why [this happens](https://discourse.processing.org/t/beziervertex-draws-straight-lines-not-a-curved-line/3139/5) when a shape that should be a `PATH` `family` is assigned the `GEOMETRY` family instead.
[beginContour](https://github.com/processing/processing/blob/94144be998354ecf7a06d5301b7b4fab72df724c/core/src/processing/core/PShape.java#L654) inserts a `BREAK` command into the vertex commands list, so maybe you could use that in conjunction with a [vertex winding algorithm](https://gamedev.stackexchange.com/questions/30537/how-to-determine-counter-clockwise-vertex-winding) to get what you’re looking for.
(Also, beware of implementation differences between a super-class `PShape` and its sub-classes, for example `PShapeOpenGL`).
EDIT: When I wanted to convert between a PShape and my own 2D curve class, I used this [routine](https://github.com/behreajj/CamZup/blob/bd01c7a57370ea16956c657f9c59b4704370fab7/src/camzup/pfriendly/Convert.java#L1356) to loop through the commands. The code does _not_ address contours but it may offer a basic outline.
Hope that helps some, Jeremy
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### Author:  [@micycle](https://discourse.processing.org/u/micycle)
#### Post date: [January 12, 2021, 8:38pm UTC](https://discourse.processing.org/t/how-are-pshape-contours-stored/26997/3 "2021-01-12T20:38:13Z")
Thanks for your reply Jeremy.
After a bit more digging around in `PShape`, I found a block of code [here](https://github.com/processing/processing/blob/master/core/src/processing/core/PShape.java#L1814) that reveals the logic of the vertex codes (for the super class at least). Reversing it is simple:
```auto
static int[] getContourGroups(int[] vertexCodes) {
int group = 0;
ArrayList groups = new ArrayList<>(vertexCodes.length * 2);
for (int vertexCode : vertexCodes) {
switch (vertexCode) {
case VERTEX:
groups.add(group);
break;
case QUADRATIC_VERTEX:
groups.add(group);
groups.add(group);
break;
case BEZIER_VERTEX:
groups.add(group);
groups.add(group);
groups.add(group);
break;
case CURVE_VERTEX:
groups.add(group);
break;
case BREAK:
/*
* Marks beginning/end of new contour, and should be proceeded by a VERTEX
*/
group++;
break;
}
}
final int[] vertexGroups = new int[groups.size()];
Arrays.setAll(vertexGroups, groups::get);
return vertexGroups;
}
```
