20 lines
914 B
Markdown
20 lines
914 B
Markdown
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---
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title: "GJK2D"
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date: 2019-09-14T22:47:55-07:00
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weight: 10
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---
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Bonk uses the Gilbert-Johnson-Keerthi, or GJK, algorithm to perform narrow phase collision detection.
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To accurately check a collision, you must pass two sets of shapes and transforms. Remember that a transform operates on the vertices of a shape: it moves, rotates, and scales them in 2D space.
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```cs
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var circleA = new Circle(2);
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var transformA = new Transform2D(new Vector2(-1, -1));
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var circleB = new Circle(2);
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var transformB = new Transform2D(new Vector2(1, 1));
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var (result, simplex) = GJK2D.TestCollision(circleA, transformA, circleB, transformB);
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```
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Note that this method returns two variables. The first is whether an overlap has occurred. The second is the simplex. You can think of the simplex as a key that helps you find the minimum separating vector. Note that if there was no collision, the value of the simplex is irrelevant.
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