vector.p8

A simple and lightweight (in tokens) vector math library for PICO-8. This library contains no error handling at all. It's a side effect of keeping it low in tokens, so you're gonna have to be responsible of whatever goes in.

Usage:

load #vector_p8
Save as such: vector.p8.
Remove all the demo code; it's in the second tab.
#include in any cart you want.

Functions within:

Creation and management

vector(x,y,z) - The function. Vectors are just normal Lua tables with x, y and z fields, so you can pass any table that contains x, y and z to any of the functions and it'll work just fine.

v_polar(length,angle)- Makes a vector using polar coordinates.
v_rnd() - Gives a normalized vector with a random direction.

v_cpy(v) - Copies a vector.
v_unpck(v) - Unpacks a vector.
v_arr(v) - Returns a vector as an array of the 3 components that comprise it. Ignore the third value (Z) if your vector is a 2D one.
v_tostr(v,d) - Turns a vector into a string. The d parameter is used to know if it should be printed as a 3D vector or not.
v_isvec(v) - Checks if a certain value is a vector.

Actual math

v_add(a,b) - Adds two vectors of any dimension.
v_sub(a,b) - Subtracts two vectors of any dimension.
v_scl(v,n) - Scales a vector by a scalar (normal number).
v_mul(v,n) - Alias for v_scl.
v_div(v,n) - Scales a vector by the inverse of a scalar ("divides" the vector).

v_dot(a,b) - Computes the dot product of two vectors.
v_cross(a,b) - Computes the cross product of two 3D vectors.
v_magsq(v) - Computes the magnitude squared of a vector.
v_mag(v) - Computes the magnitude of a vector.
v_dstsq(a,b) - Computes the distance squared between two vectors.
v_dst(a,b) - Computes the distance between two vectors.
v_norm(v) - Normalizes a vector.
v_perp(v) - Gets a 2D vector perpendicular to the passed one.
v_sprj(a,b) - Returns the scalar projection of one 2D vector in another.
v_proj(a,b) - Returns the actual projection of one 2D vector in another.

Rotation related functions

WARNING! None of these functions work with 3D vectors. When passing in 3D vectors, the result will always be 2D. All these functions work with revolutions according to PICO-8's convention.

v_rot(v,t) - Rotates a vector by an angle t.
v_ang(v) - Gets the direction a vector is pointing towards.
v_atwds(a,b) - Gets the angle needed to point towards another vector.

Miscellaneous

v_lerp(a,b,t) - Linearly interpolates two vectors.
v_flr(v) - Floors a vector.
v_eq(a,b) - Checks if two vectors are equal.

Constants

WARNING! Because of the way Lua tables work, do NOT use compound assignments to alter a variable if you directly assign one of these constants to it. Either copy the constant using v_cpy and then assign that to the variable or use one of the functions within the library (all but v_be*d) to manipulate it.

v_right - Rightwards pointing vector.
v_left - Leftwards pointing vector.
v_up - Upwards pointing vector. Y points downward in 2D so this vector points towards -Y.
v_down - Downwards pointing vector. Y points downward in 2D so this vector points towards +Y.

v_above - 3D vector pointing upwards. Unlike 2D, Y in 3D points upwards, so this vector points towards +Y.
v_below - 3D vector pointing downwards. Unlike 2D, Y in 3D points upwards, so this vector points towards -Y.
v_front - 3D vector pointing forwards.
v_back - 3D vector pointing backwards.

v_zero - Zero vector. All components are set to 0.
v_one - Identity vector. All components are set to 1.

v_cntr - Utility vector pointing towards the center of the screen, i.e. [64,64].

Changelog

v1.2.1 (11-03-2023):

Thought I had fixed all functions that used v_getd, but turns out one function I hadn't added to the docs, v_flr, still used it.
Documented v_flr.
Improved explanation for v_atwds.

v1.2 (06-12-2022):

Fixed the math functions v_add, v_sub, v_scl, v_div and v_neg using the now-defunct v_getd function.

v1.1 (09-11-2022):

Removed all dimension related functions.
Consequently, a parameter was added to v_tostr for it to know how to format the output.
Added v_sprj and v_proj.
Renamed v_center to v_cntr.

v1.0 (09-11-2022):