Week 8 Day 2 - Cross Product

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Bill Kerney

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Published on March 5, 2021 5:01:10 AM ● Video Link: https://www.youtube.com/watch?v=8zQ-lriP3h0

Duration: 1:31:46

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The first half of class we talked game design, specifically talking about how Dungeons and Dragon made making a decision about what weapon to pick an interesting one. Key takeaway point: Don't just have one axis (such as damage) to select which weapon you want, or it becomes boring (like in World of Warcraft).


The second half we talked about crossproduct, which can be used in two versions:
1) Scalar crossproduct, in which we input two normalized vectors and get a scalar number between -1 and 1 as the output. Negative numbers means that the second vector is the on the left or right side of the first vector and positive results mean the other side. (Which is which doesn't matter, it just depends on which vector is first and which is second.) Equation: x1y2-x2y1
2) Vector crossproduct, in which case it crossproduct creates a new vector that is orthogonal (at a 90 degree angle) to both of the input vectors. For example, if you have two vectors making up two arms of a triangle, the crossproduct gives you the normal vector (a vector orthogonal to the surface of the triangle).


Uses? Whereas dotproduct tells you if something is in front or behind an object, crossproduct is used to tell you if it is to the left or right, or to create a normal vector.