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CUGL 2.1
Cornell University Game Library
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CUGL 2.1
Cornell University Game Library
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#include <CUComplexExtruder.h>
Public Member Functions | |
| ComplexExtruder () | |
| ComplexExtruder (const std::vector< Vec2 > &points, bool closed) | |
| ComplexExtruder (const Path2 &path) | |
| ~ComplexExtruder () | |
| void | setJoint (poly2::Joint joint) |
| poly2::Joint | getJoint () const |
| void | setEndCap (poly2::EndCap endcap) |
| poly2::EndCap | getEndCap () const |
| void | setMitreLimit (float limit) |
| float | getMitreLimit () const |
| void | setResolution (Uint32 resolution) |
| Uint32 | getResolution () const |
| void | set (const std::vector< Vec2 > &points, bool closed) |
| void | set (const Vec2 *points, size_t size, bool closed) |
| void | set (const Path2 &path) |
| void | reset () |
| void | clear () |
| void | calculate (float stroke) |
| Poly2 | getPolygon () const |
| Poly2 * | getPolygon (Poly2 *buffer) const |
| std::vector< Path2 > | getBorder () const |
| size_t | getBorder (std::vector< Path2 > &buffer) const |
This class is a factory for extruding wireframe paths into a solid path.
An extrusion of a path is a polygon that follows the path but gives it width. Hence it takes a path and turns it into a solid shape. This is more complicated than simply triangulating the original path. The new polygon has more vertices, depending on the choice of joint (shape at the corners) and cap (shape at the end).
This class is significantly more accurate than SimpleExtruder. The extruded shape has no overlapping triangles and is safe to use with transparency. However, this comes at massive cost in speed. Even a simple line can take a full millisecond to compute, and more complicated paths will significantly affect frame rate. If you need to extrude a path at framerate, you should use SimpleExtruder instead, and pre-render to a texture if you need transparency.
As with all factories, the methods are broken up into three phases: initialization, calculation, and materialization. To use the factory, you first set the data (in this case a set of vertices or Path2 object) with the initialization methods. You then call the calculation method. Finally, you use the materialization methods to access the data in several different ways.
This division allows us to support multithreaded calculation if the data generation takes too long. However, note that this factory is not thread safe in that you cannot access data while it is still in mid-calculation.
| cugl::ComplexExtruder::ComplexExtruder | ( | ) |
Creates an extruder with no vertex data.
| cugl::ComplexExtruder::ComplexExtruder | ( | const std::vector< Vec2 > & | points, |
| bool | closed | ||
| ) |
Creates an extruder with the given vertex data.
The vertex data is copied. The extruder does not retain any references to the original data.
| points | The vertices to extrude |
| closed | Whether the path is closed |
| cugl::ComplexExtruder::ComplexExtruder | ( | const Path2 & | path | ) |
Creates an extruder with the given vertex data.
The path data is copied. The extruder does not retain any references to the original data.
| path | The vertices to extrude |
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Deletes this extruder, releasing all resources.
| void cugl::ComplexExtruder::calculate | ( | float | stroke | ) |
Performs a extrusion of the current vertex data.
An extrusion of a polygon is a second polygon that follows the path of the first one, but gives it width. Hence it takes a path and turns it into a solid shape. This is more complicated than simply triangulating the original polygon. The new polygon has more vertices, depending on the choice of joint (shape at the corners) and cap (shape at the end).
This method uses the Clipper library to perform the extrusion. While accurate and the preferred for static shapes, it is not ideal to call this method at framerate. Furthermore, while Clipper produces the boundary path of the extrusion, it does not triangulate it. This class uses a DelaunayTriangulator to complete the calculation, as that triangulator produces the best triangles for geometric purposes.
| stroke | The stroke width of the extrusion |
| void cugl::ComplexExtruder::clear | ( | ) |
Clears all internal data, including initial vertex data.
When this method is called, you will need to set a new vertices before calling calculate. However, the joint, cap, and precision settings are preserved.
| std::vector<Path2> cugl::ComplexExtruder::getBorder | ( | ) | const |
Returns a (closed) path representing the extrusion border(s)
So long as the calculation is complete, the vector is guaranteed to contain at least one path. Counter-clockwise paths correspond to the exterior boundary of the stroke. Clockwise paths are potential holes in the extrusion. There is no guarantee on the order of the returned paths.
If the calculation is not yet performed, this method will return the empty path.
| size_t cugl::ComplexExtruder::getBorder | ( | std::vector< Path2 > & | buffer | ) | const |
Stores a (closed) path representing the extrusion border in the buffer
So long as the calculation is complete, the vector is guaranteed to contain at least one path. Counter-clockwise paths correspond to the exterior boundary of the stroke. Clockwise paths are potential holes in the extrusion. There is no guarantee on the order of the returned paths.
This method will append append its results to the provided buffer. It will not erase any existing data. You should clear the buffer first if you do not want to preserve the original data.
If the calculation is not yet performed, this method will do nothing.
| buffer | The buffer to store the path around the extrusion |
| poly2::EndCap cugl::ComplexExtruder::getEndCap | ( | ) | const |
Returns the end cap value for the extrusion.
The end cap type determines how the extrusion draws the ends of the line segments at the start and end of the path. See poly2::EndCap for the description of the types.
| poly2::Joint cugl::ComplexExtruder::getJoint | ( | ) | const |
Returns the joint value for the extrusion.
The joint type determines how the extrusion joins the extruded line segments together. See poly2::Joint for the description of the types.
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Returns the mitre limit of the extrusion.
The mitre limit sets how "pointy" a mitre joint is allowed to be before the algorithm switches it back to a bevel/square joint. Small angles can have very large mitre offsets that go way off-screen.
In the case of Clipper, the mitre limit is the maximum distance in multiples of delta that vertices can be offset from their original positions before squaring is applied. By default this value is 2 (e.g. twice delta). That is also the smallest value allowed.
| Poly2 cugl::ComplexExtruder::getPolygon | ( | ) | const |
Returns a polygon representing the path extrusion.
The polygon contains the a completely new set of vertices together with the indices defining the extrusion path. The extruder does not maintain references to this polygon and it is safe to modify it.
If the calculation is not yet performed, this method will return the empty polygon.
Stores the path extrusion in the given buffer.
This method will add both the new vertices, and the corresponding indices to the new buffer. If the buffer is not empty, the indices will be adjusted accordingly. You should clear the buffer first if you do not want to preserve the original data.
If the calculation is not yet performed, this method will do nothing.
| buffer | The buffer to store the extruded polygon |
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Returns the subdivision resolution for the Clipper library.
Clipper is not only accurate, it is also computationally stable. However, it achieves this stable by only using integer coordinates. This class supports float coordinates, but it does it by scaling the points to fit on an integer grid.
The resolution is the scaling factor before rounding the points to the nearest integer. It is effectively the same as specifying the number of integer subdivisions supported. For example, if the resolution is 8 (the default), then every point will be rounded to the nearest 1/8 value.
| void cugl::ComplexExtruder::reset | ( | ) |
Clears all computed data, but still maintains the settings.
This method preserves all initial vertex data, as well as the joint, cap, and precision settings.
| void cugl::ComplexExtruder::set | ( | const Path2 & | path | ) |
Sets the path for this extruder.
The path data is copied. The extruder does not retain any references to the original data.
This method resets all interal data. You will need to reperform the calculation before accessing data.
| path | The path to extrude |
| void cugl::ComplexExtruder::set | ( | const std::vector< Vec2 > & | points, |
| bool | closed | ||
| ) |
Sets the vertex data for this extruder.
The vertex data is copied. The extruder does not retain any references to the original data.
This method resets all interal data. You will need to reperform the calculation before accessing data.
| points | The vertices to extruder |
| closed | Whether the path is closed |
| void cugl::ComplexExtruder::set | ( | const Vec2 * | points, |
| size_t | size, | ||
| bool | closed | ||
| ) |
Sets the path for this extruder.
The path data is copied. The extruder does not retain any references to the original data. All points will be considered to be corner points.
This method resets all interal data. You will need to reperform the calculation before accessing data.
| points | The path to extrude |
| size | The number of points |
| closed | Whether the path is closed |
| void cugl::ComplexExtruder::setEndCap | ( | poly2::EndCap | endcap | ) |
Sets the end cap value for the extrusion.
The end cap type determines how the extrusion draws the ends of the line segments at the start and end of the path. See poly2::EndCap for the description of the types.
| endcap | The extrusion end cap type |
| void cugl::ComplexExtruder::setJoint | ( | poly2::Joint | joint | ) |
Sets the joint value for the extrusion.
The joint type determines how the extrusion joins the extruded line segments together. See poly2::Joint for the description of the types.
| joint | The extrusion joint type |
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Sets the mitre limit of the extrusion.
The mitre limit sets how "pointy" a mitre joint is allowed to be before the algorithm switches it back to a bevel/square joint. Small angles can have very large mitre offsets that go way off-screen.
In the case of Clipper, the mitre limit is the maximum distance in multiples of delta that vertices can be offset from their original positions before squaring is applied. By default this value is 2 (e.g. twice delta). That is also the smallest value allowed.
| limit | The mitre limit for joint calculations |
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Sets the subdivision resolution for the Clipper library.
Clipper is not only accurate, it is also computationally stable. However, it achieves this stable by only using integer coordinates. This class supports float coordinates, but it does it by scaling the points to fit on an integer grid.
The resolution is the scaling factor before rounding the points to the nearest integer. It is effectively the same as specifying the number of integer subdivisions supported. For example, if the resolution is 8 (the default), then every point will be rounded to the nearest 1/8 value.
| resolution | The subdivision resolution |
1.8.16