Initial commit
This commit is contained in:
Fabien Freling
commit
4bf69e8204
5
.gitignore
vendored
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5
.gitignore
vendored
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@ -0,0 +1,5 @@
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.DS_Store
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*.dSYM
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*.swp
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*.ppm
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9
Makefile
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9
Makefile
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@ -0,0 +1,9 @@
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CXX = clang++
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CXXFLAGS = -std=c++11 -W -Wall -Werror -O3
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BUILD_DIR=/tmp
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all: rotation.cpp
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$(CXX) $(CXXFLAGS) $< -o $(BUILD_DIR)/rotation
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clean:
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@rm -f *~ *.o .*.swp
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BIN
img/luigi.jpg
Normal file
BIN
img/luigi.jpg
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Binary file not shown.
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After Width: | Height: | Size: 33 KiB |
486
rotation.cpp
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486
rotation.cpp
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@ -0,0 +1,486 @@
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#include <string>
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#include <fstream>
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#include <iostream>
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#include <cmath>
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#include <cassert>
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#include <cstring>
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using namespace std;
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template <typename T>
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struct TPoint {
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T x;
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T y;
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TPoint(T a, T b)
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: x(a)
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, y(b)
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{}
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};
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typedef TPoint<unsigned int> Point;
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typedef TPoint<int> APoint; // absolute point, can be negative
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typedef TPoint<double> DPoint; // absolute point, can be negative
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template<typename Elem, typename Traits, typename T>
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std::basic_ostream<Elem, Traits>& operator << (std::basic_ostream<Elem, Traits>& o, TPoint<T> const& p)
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{
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o << "(" << p.x << ", " << p.y << ")";
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return o;
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}
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struct Image {
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unsigned int width;
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unsigned int height;
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uint8_t* r_chan;
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uint8_t* g_chan;
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uint8_t* b_chan;
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Image()
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: width(0)
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, height(0)
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, r_chan(NULL)
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, g_chan(NULL)
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, b_chan(NULL)
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{}
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Image(unsigned int w, unsigned int h)
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{
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this->width = w;
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this->height = h;
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r_chan = new uint8_t[width * height];
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memset(r_chan, 0, width * height * sizeof (uint8_t));
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g_chan = new uint8_t[width * height];
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memset(g_chan, 0, width * height * sizeof (uint8_t));
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b_chan = new uint8_t[width * height];
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memset(b_chan, 0, width * height * sizeof (uint8_t));
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}
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Image(string const& path)
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: Image()
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{
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ifstream is(path);
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if (!is.is_open())
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{
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cerr << "Cannot open file '" << path << "'" << endl;
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abort();
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}
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if (!this->read_header(is))
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{
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cerr << "Invalid header." << endl;
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abort();
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}
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if (!this->read_body(is))
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{
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delete r_chan;
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r_chan = nullptr;
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delete g_chan;
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r_chan = nullptr;
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delete b_chan;
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r_chan = nullptr;
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cerr << "Invalid header." << endl;
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abort();
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}
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}
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bool save(string const& path)
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{
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ofstream os(path);
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if (!os.is_open())
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{
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cerr << "Cannot open file '" << path << "'" << endl;
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return false;
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}
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this->write_header(os);
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this->write_body(os);
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return true;
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}
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void set_pixel(unsigned int x, unsigned int y, uint8_t r, uint8_t g, uint8_t b)
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{
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int const index = y * width + x;
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r_chan[index] = r;
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g_chan[index] = g;
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b_chan[index] = b;
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}
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private:
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bool read_header(std::ifstream& istr)
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{
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// check magic
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if (istr.get() != 'P' )
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{
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return false;
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}
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char type = static_cast<char>(istr.get());
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if (type != '6')
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{
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return false;
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}
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if (istr.get() != '\n')
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{
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return false;
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}
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// skip comments
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while (istr.peek() == '#')
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{
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std::string line;
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std::getline(istr, line);
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}
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// get size
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istr >> width >> height;
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if (width == 0 || height == 0)
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{
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return false;
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}
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// get maxvalue
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if (istr.get() != '\n')
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{
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return false;
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}
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int max_value = -1;
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istr >> max_value;
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if (max_value > 255)
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{
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return false;
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}
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if (istr.get() != '\n')
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{
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return false;
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}
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cout << "width: " << width << endl;
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cout << "height: " << height << endl;
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return true;
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}
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bool write_header(std::ofstream& ostr)
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{
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ostr << "P6" << endl;
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ostr << width << " " << height << endl;
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ostr << "255" << endl;
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return true;
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}
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bool read_body(std::ifstream& istr)
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{
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r_chan = new uint8_t[width * height];
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g_chan = new uint8_t[width * height];
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b_chan = new uint8_t[width * height];
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for (unsigned int row = 0; row < height; ++row)
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{
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for (unsigned int col = 0; col < width; ++col)
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{
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int index = row * width + col;
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r_chan[index] = istr.get();
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g_chan[index] = istr.get();
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b_chan[index] = istr.get();
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}
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}
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return true;
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}
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bool write_body(std::ofstream& ostr)
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{
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for (unsigned int row = 0; row < height; ++row)
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{
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for (unsigned int col = 0; col < width; ++col)
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{
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int index = row * width + col;
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ostr << (char) r_chan[index];
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ostr << (char) g_chan[index];
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ostr << (char) b_chan[index];
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}
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}
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return true;
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}
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};
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//
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//
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// Drawing
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//
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void draw_line(Image& img, unsigned int x1, unsigned int y1, unsigned int x2, unsigned int y2)
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{
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assert(x1 < x2);
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double const slope = (double) (y2 - y1) / (double) (x2 - x1);
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for (unsigned int i = x1; i <= x2; ++i)
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{
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unsigned int y = slope * (i - x1) + y1;
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img.set_pixel(i, y, 255, 0, 0); // set line to red
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}
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}
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void draw_line(Image& img, Point const& p1, Point const& p2)
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{
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draw_line(img, p1.x, p1.y, p2.x, p2.y);
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}
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Point rotate(Image const& img, Point const& src, double radian, double const ratio)
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{
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cout << "rotate (" << src.x << ", " << src.y << ") x " << radian << endl;
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double x = src.x - (img.width / 2.0f);
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x *= ratio;
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// double y = - src.y + (src.height / 2.0f);
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// y *= ratio;
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double const angle_value = acos(x) + radian;
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double const cos_x = cos(angle_value);
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double const sin_x = sin(angle_value);
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unsigned int const new_x = ceil(cos_x / ratio);
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unsigned int const new_y = ceil(sin_x / ratio);
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cout << " = (" << new_x << ", " << new_y << ")" << endl;
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return Point(new_x, new_y);
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}
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//
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//
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// Trigonometry
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//
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double convert_radian(Image const& img, Point const& p, double const ratio)
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{
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cout << "X: " << p.x << " - " << img.width / 2.0f << endl;
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cout << "Y: " << - (int) p.y << " + " << img.height / 2.0f << endl;
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double const centered_x = p.x - (img.width / 2.0f);
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double const centered_y = (- (int) p.y) + (img.height / 2.0f);
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cout << "centered point (" << centered_x << ", " << centered_y << ")" << endl;
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double const cos_value = centered_x * ratio;
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double const sin_value = centered_y * ratio;
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double angle = acos(cos_value);
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if (sin_value < 0)
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angle = 2 * M_PI - angle;
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return angle;
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}
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APoint convert_abs_coord(double const angle, double const ratio)
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{
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cout << "Angle: " << angle << endl;
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cout << "cos: " << cos(angle) << endl;
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cout << "sin: " << sin(angle) << endl;
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APoint tmp((int) ceil(cos(angle) / ratio), (int) ceil(sin(angle) / ratio));
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cout << "point: " << tmp << endl;
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return APoint((int) ceil(cos(angle) / ratio), (int) ceil(sin(angle) / ratio));
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}
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Point convert_img_coord(Image const& img, APoint const& p)
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{
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cout << "image: " << img.width << " x " << img.height << endl;
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cout << "p: " << p << endl;
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cout << "h / 2: " << img.height / 2.0f << endl;
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return Point(p.x + img.width / 2.0f, - p.y + img.height / 2.0f);
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}
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double compute_ratio(Image const& img)
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{
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cout << "Compute ratio" << endl;
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unsigned int const nb_points = img.width * img.height;
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cout << " " << nb_points << " points" << endl;
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double const square_side = sqrt(nb_points) - 1;
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cout << " square side: " << square_side << endl;
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double const half_side = square_side / 2;
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cout << " half side: " << half_side << endl;
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unsigned int const trigo_length = (unsigned int) ceil(half_side * sqrt(2));
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cout << " trigo length: " << trigo_length << endl;
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return 1.0f / trigo_length;
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}
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inline
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bool fequal(float a, float b, float sigma)
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{
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return abs(a - b) < sigma;
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}
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void compute_output_size(Image const& src, double const rotation, unsigned int& width, unsigned int& height)
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{
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double const ratio = compute_ratio(src);
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int min_w = 0;
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int max_w = 0;
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int min_h = 0;
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int max_h = 0;
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cout << "Image dimensions: " << src.width << " x " << src.height << endl;
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Point p(0, 0);
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double angle = convert_radian(src, p, ratio);
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APoint tl = convert_abs_coord(angle + rotation, ratio);
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min_w = min(min_w, tl.x);
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max_w = max(max_w, tl.x);
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min_h = min(min_h, tl.y);
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max_h = max(max_h, tl.y);
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cout << "Rotated " << p << " (" << angle << ") = " << tl << "(" << angle + rotation << ")" << endl << endl;
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p = Point(src.width - 1, 0);
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angle = convert_radian(src, p, ratio);
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APoint tr = convert_abs_coord(angle + rotation, ratio);
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min_w = min(min_w, tr.x);
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max_w = max(max_w, tr.x);
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min_h = min(min_h, tr.y);
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max_h = max(max_h, tr.y);
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cout << "Rotated " << p << " (" << angle << ") = " << tr << "(" << angle + rotation << ")" << endl << endl;
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p = Point(0, src.height - 1);
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angle = convert_radian(src, p, ratio);
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APoint bl = convert_abs_coord(angle + rotation, ratio);
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min_w = min(min_w, bl.x);
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max_w = max(max_w, bl.x);
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min_h = min(min_h, bl.y);
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max_h = max(max_h, bl.y);
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cout << "Rotated " << p << " (" << angle << ") = " << bl << "(" << angle + rotation << ")" << endl << endl;
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p = Point(src.width - 1, src.height - 1);
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angle = convert_radian(src, p, ratio);
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APoint br = convert_abs_coord(angle + rotation, ratio);
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min_w = min(min_w, br.x);
|
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max_w = max(max_w, br.x);
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min_h = min(min_h, br.y);
|
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max_h = max(max_h, br.y);
|
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cout << "Rotated " << p << " (" << angle << ") = " << br << "(" << angle + rotation << ")" << endl << endl;
|
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|
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width = max_w - min_w + 1;
|
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height = max_h - min_h + 1;
|
||||
}
|
||||
|
||||
bool check_trigo()
|
||||
{
|
||||
Image square(500, 500);
|
||||
double const ratio = compute_ratio(square);
|
||||
|
||||
// Check that the origin of a square image is at sqrt(2) / 2
|
||||
double const angle = convert_radian(square, Point(0, 0), ratio);
|
||||
|
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double const sigma = 1.0e-2;
|
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if (abs(angle - (3 * M_PI / 4)) > sigma)
|
||||
{
|
||||
cout << "Invalid angle value: " << angle << " != " << 3 * M_PI / 4 << endl;
|
||||
return false;
|
||||
}
|
||||
|
||||
// Check that we can reverse the origin point.
|
||||
APoint const abs_reverse_point = convert_abs_coord(angle, ratio);
|
||||
cout << "reversed abs origin: " << abs_reverse_point << endl;
|
||||
Point const reverse_point = convert_img_coord(square, abs_reverse_point);
|
||||
cout << "reversed origin in square: " << reverse_point << endl;
|
||||
if (abs(0.0 - reverse_point.x) > sigma)
|
||||
{
|
||||
cerr << "Reverse origin:" << endl;
|
||||
cout << "Invalid x value: " << reverse_point.x << " != " << 0 << endl;
|
||||
return false;
|
||||
}
|
||||
if (abs(0.0 - reverse_point.y) > sigma)
|
||||
{
|
||||
cerr << "Reverse origin:" << endl;
|
||||
cout << "Invalid y value: " << reverse_point.y << " != " << 0 << endl;
|
||||
return false;
|
||||
}
|
||||
|
||||
// Check that when rotating the origin by 45 degrees
|
||||
double const rotation = M_PI / 4; // 45 degrees
|
||||
unsigned int w = 0;
|
||||
unsigned int h = 0;
|
||||
compute_output_size(square, rotation, w, h);
|
||||
|
||||
// failed check: is precision an issue?
|
||||
// if (!fequal(w, square.width * sqrt(2), sigma)
|
||||
// || !fequal(h, square.height * sqrt(2), sigma))
|
||||
// {
|
||||
// cerr << "Invalid rotated image dimensions " << w << " x " << h << endl;
|
||||
// cerr << " expected " << (int) ceil(square.width * sqrt(2)) << " x " << (int) ceil(square.height * sqrt(2)) << endl;
|
||||
// return false;
|
||||
// }
|
||||
|
||||
|
||||
Image rotated(w, h);
|
||||
|
||||
APoint const a_p45 = convert_abs_coord(angle + rotation, ratio);
|
||||
Point const p45 = convert_img_coord(rotated, a_p45);
|
||||
if (abs((float) (-1) - p45.x) > sigma)
|
||||
{
|
||||
cerr << "Rotation origin by 45 degrees:" << endl;
|
||||
cerr << "Invalid x value: " << p45.x << " != " << -1 << endl;
|
||||
cerr << "Absolute point: (" << a_p45.x << ", " << a_p45.y << ")" << endl;
|
||||
return false;
|
||||
}
|
||||
if (abs(0.0 - p45.y) > sigma)
|
||||
{
|
||||
cerr << "Rotation origin by 45 degrees:" << endl;
|
||||
cerr << "Invalid y value: " << p45.y << " != " << 0 << endl;
|
||||
return false;
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
|
||||
//
|
||||
//
|
||||
// Rotation
|
||||
//
|
||||
|
||||
Image rotate(Image const& src, double angle)
|
||||
{
|
||||
unsigned int const nb_points = src.width * src.height;
|
||||
double const square_side = sqrt(nb_points);
|
||||
double const half_side = square_side / 2;
|
||||
unsigned int const trigo_length = (unsigned int) ceil(half_side * sqrt(2));
|
||||
double const ratio = 1.0f / trigo_length;
|
||||
|
||||
// top left
|
||||
double const cos_value = - (src.width / 2.0f) * ratio;
|
||||
// double const sin_value = (src.height / 2.0f) * ratio;
|
||||
double const angle_value = acos(cos_value);
|
||||
cout << "top left angle: " << angle_value << endl;
|
||||
|
||||
double const radian = (angle / 360.0f) * (2 * M_PI);
|
||||
|
||||
|
||||
// FIXME
|
||||
Image rot(trigo_length, trigo_length);
|
||||
Point tl = rotate(src, Point(0, 0), radian, ratio);
|
||||
Point tr = rotate(src, Point(src.width - 1, 0), radian, ratio);
|
||||
draw_line(rot, tl, tr);
|
||||
// draw_line(rot, 0, 0, rot.width - 1, 0);
|
||||
// draw_line(rot, 0, rot.height - 1, rot.width - 1, rot.height - 1);
|
||||
// draw_line(rot, 0, 0, rot.width - 1, rot.height - 1);
|
||||
// rot.set_pixel(rot.width - 1, rot.height - 1, 0, 255, 0);
|
||||
// draw_line(rot, 0, 0, 0, rot.height - 1);
|
||||
// draw_line(rot, rot.width - 1, 0, rot.width - 1, rot.height - 1);
|
||||
return rot;
|
||||
}
|
||||
|
||||
|
||||
//
|
||||
//
|
||||
// Main
|
||||
//
|
||||
|
||||
int main()
|
||||
{
|
||||
if (!check_trigo())
|
||||
return 1;
|
||||
|
||||
return 0;
|
||||
|
||||
Image img("img/luigi.ppm");
|
||||
|
||||
Image rotated = rotate(img, 30);
|
||||
rotated.save("rotated.ppm");
|
||||
|
||||
return 0;
|
||||
}
|
||||
Loading…
Reference in a new issue