Finally have a name for my little matrix shape iterator library. I present to you, the SHITErators. Are they THE shit? Shit? Or just Shite?
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#pragma once |
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#include <vector> |
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#include <queue> |
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#include <string> |
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#include <array> |
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#include <numeric> |
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#include <algorithm> |
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#include <fmt/core.h> |
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#include "point.hpp" |
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#include "rand.hpp" |
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#include "dbc.hpp" |
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|
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/*
|
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* # What is This Shit? |
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* |
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* Announcing the Shape Iterators, or `shiterators` for short. You could also say these are Shaw's Iterators, but |
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* either way they are the _shit_. Or are they shit? You decide. Maybe they're "shite"? |
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* |
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* A shiterator is a simple generator that converts 2D shapes into a 1D stream of x/y coordinates. You give it a matrix, some parameters like start, end, etc. and each time you call `next()` you the next viable x/y coordinate to complete the shape. |
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* |
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* A shiterator tries to ensure a few things: |
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* |
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* 1. All x/y values will be within the Matrix you give it. |
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* 2. They try to not store anything and only calculate the math necessary to linearlize the shape. |
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* 3. You can store them and incrementally call next to get the next value. |
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* 4. You should be able to compose them together on the same Matrix or different matrices of the same dimensions. |
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* 5. Most of them will only require 1 for-loop, the few that require 2 only do this so you can draw the inside of a shape. `circle` is like this. |
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* 6. They don't assume any particular classes or require subclassing. As long as the type given enables `mat[y][x]` (row major) access then it'll work. |
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* 7. The matrix given to a shiterator isn't actually attached to it, so you can use one matrix to setup an iterator, then apply the x/y values to any other matrix of the same dimensions. |
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* 8. More importantly, shiterators _do not return any values from the matrix_. They only do the math for coordinates and leave it to you to work your matrix. |
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* |
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* These shiterators are used all over the game to do map rendering, randomization, drawing, nearly everything that involves a shape. |
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* |
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* ## Algorithms I Need |
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* |
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* I'm currently looking for a few algorithms, so if you know how to do these let me know: |
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* |
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* 1. _Flood fill_ This turns out to be really hard because most algorithms require keeping track of visited cells with a queue, recursion, etc. |
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* 2. _Random rectangle fill_ I have something that mostly works but it's really only random across each y-axis, then separate y-axes are randomized. |
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* 3. _Dijkstra Map_ I have a Dijkstra algorithm but it's not in this style yet. Look in `worldbuilder.cpp` for my current implementation. |
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* 4. _Viewport_ Currently working on this but I need to have a rectangle I can move around as a viewport. |
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* |
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* |
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* ## Usage |
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* |
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* Check the `matrix.hpp` for an example if you want to make it more conventient for your own type. |
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* |
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* ## Thanks |
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* |
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* Special thanks for Amit and hirdrac for their help with the math and for |
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* giving me the initial idea. hirdrac doesn't want to be held responsible for |
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* this travesty but he showed me that you can do iteration and _not_ use the |
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* weird C++ iterators. Amit did a lot to show me how to do these calculations |
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* without branching. Thanks to you both and everyone helping me while I |
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* stream my development. |
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*/ |
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namespace shiterator { using std::vector, std::queue, std::array; using |
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std::min, std::max, std::floor; |
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|
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template<typename T> |
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using BaseRow = vector<T>; |
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template<typename T> |
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using Base = vector<BaseRow<T>>; |
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template<typename T> |
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inline Base<T> make(size_t width, size_t height) { |
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Base<T> result(height, BaseRow<T>(width)); |
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return result; |
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} |
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|
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/*
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* Just a quick thing to reset a matrix to a value. |
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*/ |
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template<typename MAT, typename VAL> |
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inline void assign(MAT &out, VAL new_value) { |
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for(auto &row : out) { |
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row.assign(row.size(), new_value); |
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} |
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} |
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|
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|
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/*
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* Tells you if a coordinate is in bounds of the matrix |
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* and therefore safe to use. |
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*/ |
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template<typename MAT> |
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inline bool inbounds(MAT &mat, size_t x, size_t y) { |
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// since Point.x and Point.y are size_t any negatives are massive
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return (y < mat.size()) && (x < mat[0].size()); |
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} |
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|
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/*
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* Gives the width of a matrix. Assumes row major (y/x) |
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* and vector API .size(). |
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*/ |
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template<typename MAT> |
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inline size_t width(MAT &mat) { |
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return mat[0].size(); |
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} |
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|
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/*
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* Same as shiterator::width but just the height. |
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*/ |
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template<typename MAT> |
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inline size_t height(MAT &mat) { |
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return mat.size(); |
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} |
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|
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/*
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* These are internal calculations that help |
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* with keeping track of the next x coordinate. |
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*/ |
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inline size_t next_x(size_t x, size_t width) { |
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return (x + 1) * ((x + 1) < width); |
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} |
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|
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/*
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* Same as next_x but updates the next y coordinate. |
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* It uses the fact that when x==0 you have a new |
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* line so increment y. |
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*/ |
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inline size_t next_y(size_t x, size_t y) { |
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return y + (x == 0); |
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} |
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|
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/*
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* Figures out if you're at the end of the shape, |
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* which is usually when y > height. |
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*/ |
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inline bool at_end(size_t y, size_t height) { |
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return y < height; |
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} |
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|
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/*
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* Determines if you're at the end of a row. |
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*/ |
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inline bool end_row(size_t x, size_t width) { |
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return x == width - 1; |
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} |
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|
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/*
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* Most basic shiterator. It just goes through |
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* every cell in the matrix in linear order |
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* with not tracking of anything else. |
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*/ |
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template<typename MAT> |
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struct each_cell_t { |
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size_t x = ~0; |
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size_t y = ~0; |
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size_t width = 0; |
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size_t height = 0; |
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each_cell_t(MAT &mat) |
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{ |
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height = shiterator::height(mat); |
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width = shiterator::width(mat); |
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} |
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|
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bool next() { |
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x = next_x(x, width); |
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y = next_y(x, y); |
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return at_end(y, height); |
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} |
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}; |
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|
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/*
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* This is just each_cell_t but it sets |
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* a boolean value `bool row` so you can |
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* tell when you've reached the end of a |
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* row. This is mostly used for printing |
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* out a matrix and similar just drawing the |
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* whole thing with its boundaries. |
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*/ |
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template<typename MAT> |
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struct each_row_t { |
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size_t x = ~0; |
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size_t y = ~0; |
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size_t width = 0; |
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size_t height = 0; |
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bool row = false; |
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each_row_t(MAT &mat) { |
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height = shiterator::height(mat); |
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width = shiterator::width(mat); |
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} |
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bool next() { |
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x = next_x(x, width); |
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y = next_y(x, y); |
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row = end_row(x, width); |
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return at_end(y, height); |
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} |
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}; |
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|
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/*
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* This is a CENTERED box, that will create |
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* a centered rectangle around a point of a |
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* certain dimension. This kind of needs a |
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* rewrite but if you want a rectangle from |
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* a upper corner then use rectangle_t type. |
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* |
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* Passing 1 parameter for the size will make |
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* a square. |
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*/ |
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template<typename MAT> |
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struct box_t { |
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size_t from_x; |
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size_t from_y; |
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size_t x = 0; // these are set in constructor
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size_t y = 0; // again, no fancy ~ trick needed
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size_t left = 0; |
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size_t top = 0; |
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size_t right = 0; |
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size_t bottom = 0; |
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box_t(MAT &mat, size_t at_x, size_t at_y, size_t size) : |
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box_t(mat, at_x, at_y, size, size) { |
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} |
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box_t(MAT &mat, size_t at_x, size_t at_y, size_t width, size_t height) : |
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from_x(at_x), from_y(at_y) |
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{ |
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size_t h = shiterator::height(mat); |
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size_t w = shiterator::width(mat); |
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// keeps it from going below zero
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// need extra -1 to compensate for the first next()
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left = max(from_x, width) - width; |
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x = left - 1; // must be -1 for next()
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// keeps it from going above width
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right = min(from_x + width + 1, w); |
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// same for these two
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top = max(from_y, height) - height; |
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y = top - (left == 0); |
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bottom = min(from_y + height + 1, h); |
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} |
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bool next() { |
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// calc next but allow to go to 0 for next
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x = next_x(x, right); |
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// x will go to 0, which signals new line
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y = next_y(x, y); // this must go here
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// if x==0 then this moves it to min_x
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x = max(x, left); |
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// and done
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return at_end(y, bottom); |
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} |
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/*
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* This was useful for doing quick lighting |
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* calculations, and I might need to implement |
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* it in other shiterators. It gives the distance |
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* to the center from the current x/y. |
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*/ |
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float distance() { |
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int dx = from_x - x; |
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int dy = from_y - y; |
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return sqrt((dx * dx) + (dy * dy)); |
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} |
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}; |
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/*
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* Stupid simple compass shape North/South/East/West. |
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* This comes up a _ton_ when doing searching, flood |
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* algorithms, collision, etc. Probably not the |
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* fastest way to do it but good enough. |
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*/ |
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template<typename MAT> |
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struct compass_t { |
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size_t x = 0; // these are set in constructor
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size_t y = 0; // again, no fancy ~ trick needed
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array<int, 4> x_dirs{0, 1, 0, -1}; |
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array<int, 4> y_dirs{-1, 0, 1, 0}; |
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size_t max_dirs=0; |
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size_t dir = ~0; |
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compass_t(MAT &mat, size_t x, size_t y) : |
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x(x), y(y) |
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{ |
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array<int, 4> x_in{0, 1, 0, -1}; |
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array<int, 4> y_in{-1, 0, 1, 0}; |
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for(size_t i = 0; i < 4; i++) { |
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int nx = x + x_in[i]; |
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int ny = y + y_in[i]; |
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if(shiterator::inbounds(mat, nx, ny)) { |
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x_dirs[max_dirs] = nx; |
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y_dirs[max_dirs] = ny; |
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max_dirs++; |
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} |
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} |
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} |
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bool next() { |
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dir++; |
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if(dir < max_dirs) { |
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x = x_dirs[dir]; |
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y = y_dirs[dir]; |
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return true; |
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} else { |
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return false; |
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} |
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} |
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}; |
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/*
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* Draws a line from start to end using a algorithm from |
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* https://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm
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* No idea if the one I picked is best but it's the one |
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* that works in the shiterator requirements and produced |
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* good results. |
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* |
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* _WARNING_: This one doesn't check if the start/end are |
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* within your Matrix, as it's assumed _you_ did that |
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* already. |
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*/ |
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struct line { |
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int x; |
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int y; |
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int x1; |
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int y1; |
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int sx; |
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int sy; |
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int dx; |
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int dy; |
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int error; |
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line(Point start, Point end) : |
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x(start.x), y(start.y), |
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x1(end.x), y1(end.y) |
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{ |
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dx = std::abs(x1 - x); |
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sx = x < x1 ? 1 : -1; |
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dy = std::abs(y1 - y) * -1; |
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sy = y < y1 ? 1 : -1; |
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error = dx + dy; |
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} |
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bool next() { |
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if(x != x1 || y != y1) { |
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int e2 = 2 * error; |
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if(e2 >= dy) { |
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error = error + dy; |
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x = x + sx; |
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} |
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if(e2 <= dx) { |
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error = error + dx; |
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y = y + sy; |
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} |
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return true; |
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} else { |
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return false; |
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} |
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} |
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}; |
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/*
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* Draws a simple circle using a fairly naive algorithm |
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* but one that actually worked. So, so, so, so many |
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* circle drawing algorithms described online don't work |
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* or are flat wrong. Even the very best I could find |
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* did overdrawing of multiple lines or simply got the |
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* math wrong. Keep in mind, _I_ am bad at this trig math |
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* so if I'm finding errors in your circle drawing then |
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* you got problems. |
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* |
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* This one is real simple, and works. If you got better |
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* then take the challenge but be ready to get it wrong. |
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*/ |
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template<typename MAT> |
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struct circle_t { |
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float center_x; |
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float center_y; |
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float radius = 0.0f; |
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int y = 0; |
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int dx = 0; |
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int dy = 0; |
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int left = 0; |
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int right = 0; |
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int top = 0; |
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int bottom = 0; |
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int width = 0; |
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int height = 0; |
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circle_t(MAT &mat, Point center, float radius) : |
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center_x(center.x), center_y(center.y), radius(radius) |
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{ |
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width = shiterator::width(mat); |
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height = shiterator::height(mat); |
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top = max(int(floor(center_y - radius)), 0); |
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bottom = min(int(floor(center_y + radius)), height - 1); |
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y = top; |
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} |
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bool next() { |
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y++; |
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if(y <= bottom) { |
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dy = y - center_y; |
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dx = floor(sqrt(radius * radius - dy * dy)); |
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left = max(0, int(center_x) - dx); |
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right = min(width, int(center_x) + dx + 1); |
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return true; |
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} else { |
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return false; |
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} |
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} |
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}; |
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/*
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* Basic rectangle shiterator, and like box and rando_rect_t you can |
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* pass only 1 parameter for size to do a square. |
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*/ |
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template<typename MAT> |
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struct rectangle_t { |
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int x; |
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int y; |
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int top; |
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int left; |
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int width; |
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int height; |
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int right; |
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int bottom; |
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rectangle_t(MAT &mat, size_t start_x, size_t start_y, size_t size) : |
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rectangle_t(mat, start_x, start_y, size, size) { |
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} |
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rectangle_t(MAT &mat, size_t start_x, size_t start_y, size_t width, size_t height) : |
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top(start_y), |
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left(start_x), |
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width(width), |
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height(height) |
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{ |
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size_t h = shiterator::height(mat); |
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size_t w = shiterator::width(mat); |
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y = start_y - 1; |
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x = left - 1; // must be -1 for next()
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right = min(start_x + width, w); |
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y = start_y; |
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bottom = min(start_y + height, h); |
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} |
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bool next() { |
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x = next_x(x, right); |
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y = next_y(x, y); |
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x = max(x, left); |
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return at_end(y, bottom); |
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} |
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}; |
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/*
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* WIP: This one is used to place entities randomly but |
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* could be used for effects like random destruction of floors. |
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* It simply "wraps" the rectangle_t but randomizes the x/y values |
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* using a random starting point. This makes it random across the |
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* x-axis but only partially random across the y. |
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*/ |
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template<typename MAT> |
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struct rando_rect_t { |
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int x; |
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int y; |
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int x_offset; |
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int y_offset; |
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rectangle_t<MAT> it; |
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rando_rect_t(MAT &mat, size_t start_x, size_t start_y, size_t size) : |
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rando_rect_t(mat, start_x, start_y, size, size) { |
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} |
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rando_rect_t(MAT &mat, size_t start_x, size_t start_y, size_t width, size_t height) : |
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it{mat, start_x, start_y, width, height} |
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{ |
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x_offset = Random::uniform(0, int(width)); |
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y_offset = Random::uniform(0, int(height)); |
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} |
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bool next() { |
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bool done = it.next(); |
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x = it.left + ((it.x + x_offset) % it.width); |
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y = it.top + ((it.y + y_offset) % it.height); |
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return done; |
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} |
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}; |
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/*
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* BROKEN: I'm actually not sure what I'm trying to |
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* do here yet. |
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*/ |
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template<typename MAT> |
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struct viewport_t { |
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Point start; |
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// this is the point in the map
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size_t x; |
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size_t y; |
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// this is the point inside the box, start at 0
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size_t view_x = ~0; |
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size_t view_y = ~0; |
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// viewport width/height
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size_t width; |
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size_t height; |
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viewport_t(MAT &mat, Point start, int max_x, int max_y) : |
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start(start), |
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x(start.x-1), |
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y(start.y-1) |
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{ |
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width = std::min(size_t(max_x), shiterator::width(mat) - start.x); |
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height = std::min(size_t(max_y), shiterator::height(mat) - start.y); |
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fmt::println("viewport_t max_x, max_y {},{} vs matrix {},{}, x={}, y={}", |
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max_x, max_y, shiterator::width(mat), shiterator::height(mat), x, y); |
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} |
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bool next() { |
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y = next_y(x, y); |
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x = next_x(x, width); |
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view_x = next_x(view_x, width); |
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view_y = next_y(view_x, view_y); |
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return at_end(y, height); |
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} |
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}; |
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} |
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