We're post-multiplying because we interpret all moves to be with respect to the current frame of reference, not the global frame. If we move it "right" by 10, then rotate it counter-clockwise 45°, we get a different result than if we were to turn it counter-clockwise and then move it "right".Įach step of the transformation changes the local coordinate system, and all our transformations are happening with respect to that local system: T(sq) = R(sq) * L(sq) * S(sq), or "the transform of the square is its rotation times its translation times its scale". The machinery we'll be using to concatenate all these transformations is matrix multiplication, but order matters!Īs an exercise, think about a square at the origin of a 2D graph. In the end, our transform matrices will get pretty complicated. Rotation in XY plane = this is complicated ^ Note that this is really a shear in the 4th dimension Our schema for basic transform matrices is a bit like this.Īny of these could be multiplied by a (column) vector position to map that vector onto the transformed space: One even more special case, the isometry or rigid-body transformation, does away with the scale part. One special and useful case of these transformations are the similarities (AKA "affine transformations"): a rotation followed by a translation followed by a scale. In 3D we generally use augmented 4x4 matrices to represent our transforms 1.
#Vector 2d collision how to#
We're going to go more general now with transformation matrices.Ī transformation matrix describes how to transform points or vectors from one coordinate space to another we are especially interested in linear transformations since they can be concatenated and are invertible. Professor AD ( An Expert Programmer who knows how to turn complex problems into practical solutions.As in 2D, every object can be thought of as having its own local coordinate system if objects have "child" objects, then those have their coordinate systems defined in relative terms with respect to their parents, and then their parents, and so on.īefore, we only looked at translations of 2D objects, so adding together offsets got us to where we needed to be.
#Vector 2d collision software#
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(otherTri = finalTri) //Checking for intersection between the secondtriangle with the thirdĬout << "Setting the 3rd triangle to same coords as 2nd.\n" << endl (tri = finalTri) //Checking for intersection between the first triangle with the third (tri = otherTri) //Checking for intersection between the first triangle with the second Triangle tri(0, 2, myPoints), otherTri(1.5, 2, otherPoints), finalTri(2, 2, finalPoints) OtherPoints.Set(0, 0), otherPoints.Set(0, 1), otherPoints.Set(1, 0) įinalPoints.Set(0, 0), finalPoints.Set(1, 1), finalPoints.Set(1, 0) Point myPoints, otherPoints, finalPoints *Tests the shapes, which are triangles in this case, for a collision. *Made by Alex Edwards, modified by Ancient Dragon However, this may be useful if programs want to implement objects bouncing within other objects. If a shape is fully inscribed within another shape then a vector collision may fail.
This class does NOT deal with the difference of shapes within shapes. This is still experimental code, but the tests show that if the vectors meet at a point or intersect then there will be an Intersection met notice when the vectors are compared. One can simply implement this class and define their object to consist of these vectors and call upon the Set command for each vector whenever the graphical object is moved.
Hopefully this program will be useful to those out there designing 2D graphics programs and need a better solution to determining graphical object-to-object collisions when two objects meet, without having to rely on the famous "bounding box" that many graphical objects are defined by. This is a program I designed that implements a little bit of vector-math to determine the collision between 2 vectors.