rotate-me-fast/rotation.cpp
Fabien Freling 6a94c79ac2 FIll new interpolated pixels.
- Take input image in argument.
- Allow set_pixel() out of bounds, noop.
2014-06-26 23:45:02 +02:00

769 lines
19 KiB
C++

#include <string>
#include <fstream>
#include <iostream>
#include <sstream>
#include <cmath>
#include <cassert>
#include <cstring>
#include <chrono>
using namespace std;
template <typename T>
struct TPoint {
T x;
T y;
TPoint(T a, T b)
: x(a)
, y(b)
{}
};
typedef TPoint<int> Point;
typedef TPoint<int> APoint; // absolute point, can be negative
typedef TPoint<double> DPoint; // absolute point, can be negative
template<typename Elem, typename Traits, typename T>
std::basic_ostream<Elem, Traits>& operator << (std::basic_ostream<Elem, Traits>& o, TPoint<T> const& p)
{
o << "(" << p.x << ", " << p.y << ")";
return o;
}
struct Image {
unsigned int width;
unsigned int height;
uint8_t* r_chan;
uint8_t* g_chan;
uint8_t* b_chan;
Image()
: width(0)
, height(0)
, r_chan(NULL)
, g_chan(NULL)
, b_chan(NULL)
{}
Image(unsigned int w, unsigned int h)
{
this->width = w;
this->height = h;
r_chan = new uint8_t[width * height];
memset(r_chan, 255, width * height * sizeof (uint8_t));
g_chan = new uint8_t[width * height];
memset(g_chan, 0, width * height * sizeof (uint8_t));
b_chan = new uint8_t[width * height];
memset(b_chan, 0, width * height * sizeof (uint8_t));
}
Image(string const& path)
: Image()
{
ifstream is(path);
if (!is.is_open())
{
cerr << "Cannot open file '" << path << "'" << endl;
abort();
}
if (!this->read_header(is))
{
cerr << "Invalid header." << endl;
abort();
}
if (!this->read_body(is))
{
delete r_chan;
r_chan = nullptr;
delete g_chan;
r_chan = nullptr;
delete b_chan;
r_chan = nullptr;
cerr << "Invalid header." << endl;
abort();
}
}
bool save(string const& path)
{
ofstream os(path);
if (!os.is_open())
{
cerr << "Cannot open file '" << path << "'" << endl;
return false;
}
this->write_header(os);
this->write_body(os);
return true;
}
void set_pixel(unsigned int x, unsigned int y, uint8_t r, uint8_t g, uint8_t b)
{
if (x >= width || y >= height)
{
cerr << __LINE__ << " | Point (" << x << ", " << y << ") out of bounds" << endl;
cerr << " Image dimensions: " << width << " x " << height << endl;
// assert(false);
return;
}
int const index = y * width + x;
r_chan[index] = r;
g_chan[index] = g;
b_chan[index] = b;
}
void set_pixel(Point const& p, uint8_t r, uint8_t g, uint8_t b)
{
this->set_pixel(p.x, p.y, r, g, b);
}
void get_pixel(APoint const& p, uint8_t& r, uint8_t& g, uint8_t& b) const
{
if (p.x < 0 || p.x >= (int) width || p.y < 0 || p.y >= (int) height)
{
// set out of domain pixels to black
r = 0;
g = 0;
b = 0;
return;
}
unsigned int const index = p.y * width + p.x;
r = r_chan[index];
g = g_chan[index];
b = b_chan[index];
}
private:
bool read_header(std::ifstream& istr)
{
// check magic
if (istr.get() != 'P' )
{
return false;
}
char type = static_cast<char>(istr.get());
if (type != '6')
{
return false;
}
if (istr.get() != '\n')
{
return false;
}
// skip comments
while (istr.peek() == '#')
{
std::string line;
std::getline(istr, line);
}
// get size
istr >> width >> height;
if (width == 0 || height == 0)
{
return false;
}
// get maxvalue
if (istr.get() != '\n')
{
return false;
}
int max_value = -1;
istr >> max_value;
if (max_value > 255)
{
return false;
}
if (istr.get() != '\n')
{
return false;
}
// cout << "width: " << width << endl;
// cout << "height: " << height << endl;
return true;
}
bool write_header(std::ofstream& ostr)
{
ostr << "P6" << endl;
ostr << width << " " << height << endl;
ostr << "255" << endl;
return true;
}
bool read_body(std::ifstream& istr)
{
r_chan = new uint8_t[width * height];
g_chan = new uint8_t[width * height];
b_chan = new uint8_t[width * height];
for (unsigned int row = 0; row < height; ++row)
{
for (unsigned int col = 0; col < width; ++col)
{
int index = row * width + col;
r_chan[index] = istr.get();
g_chan[index] = istr.get();
b_chan[index] = istr.get();
}
}
return true;
}
bool write_body(std::ofstream& ostr)
{
for (unsigned int row = 0; row < height; ++row)
{
for (unsigned int col = 0; col < width; ++col)
{
int index = row * width + col;
ostr << (char) r_chan[index];
ostr << (char) g_chan[index];
ostr << (char) b_chan[index];
}
}
return true;
}
};
//
//
// Trigonometry
//
DPoint convert_grid_coord(Image const& img, APoint const& p)
{
return DPoint(p.x - img.width / 2.0f + 0.5, p.y - img.height / 2.0f + 0.5);
}
double convert_radian(Image const& img, APoint const& p, double const ratio)
{
DPoint centered = convert_grid_coord(img, p);
double const cos_value = centered.x * ratio;
double const sin_value = - (centered.y * ratio);
double angle = acos(cos_value);
if (sin_value < 0)
{
angle = (2 * M_PI) - angle;
}
return angle;
}
DPoint convert_abs_coord(double const angle, double const ratio)
{
return DPoint(cos(angle) / ratio, - sin(angle) / ratio);
}
APoint convert_img_coord(Image const& img, DPoint const& p)
{
int x = round(p.x + (img.width / 2.0f) - 0.5);
int y = round(p.y + (img.height / 2.0f) - 0.5);
return APoint(x, y);
}
DPoint convert_img_coord_precision(Image const& img, DPoint const& p)
{
int x = p.x + (img.width / 2.0f) - 0.5;
int y = p.y + (img.height / 2.0f) - 0.5;
return DPoint(x, y);
}
void convert_abs_to_polar_coord(DPoint const& p, double& angle, double& dist)
{
angle = atan2(-p.y, p.x);
dist = sqrt(p.x * p.x + p.y * p.y);
}
DPoint convert_polar_to_grid_coord(double const angle, double const distance)
{
return DPoint(cos(angle) * distance, - (sin(angle) * distance));
}
double compute_ratio(Image const& img)
{
double const trigo_length = (sqrt(img.width * img.width + img.height * img.height) - 1) / 2;
return 1.0f / trigo_length;
}
inline
bool fequal(float a, float b, float sigma)
{
return abs(a - b) < sigma;
}
void compute_output_size(Image const& src, double const rotation, unsigned int& width, unsigned int& height)
{
double const ratio = compute_ratio(src);
double min_w = 0;
double max_w = 0;
double min_h = 0;
double max_h = 0;
//cout << "Image dimensions: " << src.width << " x " << src.height << endl;
APoint p(0, 0);
double angle = convert_radian(src, p, ratio);
DPoint tl = convert_abs_coord(angle + rotation, ratio);
min_w = min(min_w, tl.x);
max_w = max(max_w, tl.x);
min_h = min(min_h, tl.y);
max_h = max(max_h, tl.y);
// debug print
// if (rotation == 0.0)
// {
// cout << "Rotated " << p << " = " << tl << endl << endl;
// }
p = Point(src.width - 1, 0);
angle = convert_radian(src, p, ratio);
DPoint tr = convert_abs_coord(angle + rotation, ratio);
min_w = min(min_w, tr.x);
max_w = max(max_w, tr.x);
min_h = min(min_h, tr.y);
max_h = max(max_h, tr.y);
// if (rotation == 0.0)
// {
// cout << "Rotated " << p << " = " << tr << endl << endl;
// }
p = Point(0, src.height - 1);
angle = convert_radian(src, p, ratio);
DPoint bl = convert_abs_coord(angle + rotation, ratio);
min_w = min(min_w, bl.x);
max_w = max(max_w, bl.x);
min_h = min(min_h, bl.y);
max_h = max(max_h, bl.y);
// if (rotation == 0.0)
// {
// cout << "Rotated " << p << " = " << bl << endl << endl;
// }
p = Point(src.width - 1, src.height - 1);
angle = convert_radian(src, p, ratio);
DPoint br = convert_abs_coord(angle + rotation, ratio);
min_w = min(min_w, br.x);
max_w = max(max_w, br.x);
min_h = min(min_h, br.y);
max_h = max(max_h, br.y);
// if (rotation == 0.0)
// {
// cout << "Rotated " << p << " = " << br << endl << endl;
// }
width = (int) (max_w - min_w) + 1;
height = (int) (max_h - min_h) + 1;
}
//
//
// Point rotation
//
APoint rotate(Image const& src, Point const& p, double const ratio, double const rotation, Image const& rotated)
{
double angle = convert_radian(src, p, ratio);
DPoint a_point = convert_abs_coord(angle + rotation, ratio);
return convert_img_coord(rotated, a_point);
}
//
//
// Drawing
//
void draw_line(Image& img, unsigned int x1, unsigned int y1, unsigned int x2, unsigned int y2)
{
int x_inc = x1 <= x2 ? 1 : -1;
unsigned int const y_min = min(y1, y2);
unsigned int const y_max = max(y1, y2);
double slope = (double) y2 - y1;
if (x1 != x2)
slope = ((double) y2 - y1) / abs((double) x2 - x1);
int y_inc = slope > 0 ? 1 : -1;
if (x1 == x2)
{
for (unsigned int runner = y1; runner != y2; runner+= y_inc)
img.set_pixel(x1, runner, 255, 0, 0); // set line to red
return;
}
if (y1 == y2)
{
for (unsigned int runner = x1; runner != x2; runner+= x_inc)
img.set_pixel(runner, y1, 255, 0, 0); // set line to red
return;
}
unsigned int previous_y = y1;
for (unsigned int i = x1, steps = 0; i != x2; i += x_inc, ++steps)
{
unsigned int y = slope * steps + y1;
y = min(y, y_max);
y = max(y, y_min);
for (unsigned int runner = previous_y; runner != y; runner+= y_inc)
img.set_pixel(i, runner, 255, 0, 0); // set line to red
previous_y = y;
}
}
void draw_line(Image& img, APoint const& p1, APoint const& p2)
{
draw_line(img, p1.x, p1.y, p2.x, p2.y);
}
void draw_outline(Image const& input, unsigned int degrees, string const& name)
{
double const rotation = (degrees / 180.0f) * M_PI;
unsigned int w = 0;
unsigned int h = 0;
compute_output_size(input, rotation, w, h);
cout << "rotation(" << degrees << ") -> " << w << " x " << h << endl;
Image rotated(w, h);
double const ratio = compute_ratio(input);
APoint tl = rotate(input, Point(0, 0), ratio, rotation, rotated);
APoint tr = rotate(input, Point(input.width - 1, 0), ratio, rotation, rotated);
APoint bl = rotate(input, Point(0, input.height - 1), ratio, rotation, rotated);
APoint br = rotate(input, Point(input.width - 1, input.height - 1), ratio, rotation, rotated);
cout << tl << " " << tr << " " << bl << " " << br << endl;
draw_line(rotated, tl, tr);
draw_line(rotated, tr, br);
draw_line(rotated, br, bl);
draw_line(rotated, bl, tl);
stringstream ss;
ss << "check_lines_" << name << "_" << degrees << ".ppm";
rotated.save(ss.str());
}
//
//
// Image rotation
//
DPoint get_mapped_point(Image const& src, APoint const& p, double const rotation)
{
DPoint const d = convert_grid_coord(src, p);
double p_angle = 0;
double dist = 0;
convert_abs_to_polar_coord(d, p_angle, dist);
return convert_polar_to_grid_coord(p_angle + rotation, dist);
}
Image rotate(Image const& src, double angle)
{
double const rotation = (angle / 180.0f) * M_PI;
unsigned int w = 0;
unsigned int h = 0;
compute_output_size(src, rotation, w, h);
Image rotated(w, h);
// corner points in rotated image
DPoint tl_grid = get_mapped_point(src, APoint(0, 0), rotation);
APoint tl = convert_img_coord(rotated, tl_grid);
DPoint tr_grid = get_mapped_point(src, APoint(src.width - 1, 0), rotation);
APoint tr = convert_img_coord(rotated, tr_grid);
DPoint bl_grid = get_mapped_point(src, APoint(0, src.height - 1), rotation);
APoint bl = convert_img_coord(rotated, bl_grid);
// corner points in source image
DPoint src_tl = get_mapped_point(rotated, tl, -rotation);
src_tl = convert_img_coord_precision(src, src_tl);
DPoint src_tr = get_mapped_point(rotated, tr, -rotation);
src_tr = convert_img_coord_precision(src, src_tr);
DPoint src_bl = get_mapped_point(rotated, bl, -rotation);
src_bl = convert_img_coord_precision(src, src_bl);
// steps for first column in source image
int origin_nb_steps = max(abs(bl.x - tl.x), abs(bl.y - tl.y));
double origin_y_inc = (src_bl.y - src_tl.y) / origin_nb_steps;
double origin_x_inc = (src_bl.x - src_tl.x) / origin_nb_steps;
// steps for line in source image
int line_nb_steps = max(abs(tr.x - tl.x), abs(tr.y - tl.y));
double line_y_inc = (src_tr.y - src_tl.y) / line_nb_steps;
double line_x_inc = (src_tr.x - src_tl.x) / line_nb_steps;
// steps for first column in rotated image
double rotated_y_inc = (bl.y - tl.y) / (float) origin_nb_steps;
double rotated_x_inc = (bl.x - tl.x) / (float) origin_nb_steps;
// steps for line in rotated image
DPoint bresenham((tr.x - tl.x) / (float) line_nb_steps, (tr.y - tl.y) / (float) line_nb_steps);
for (int y_i = 0; y_i <= (int) origin_nb_steps; ++y_i)
{
// first column origin
DPoint const src_origin(src_tl.x + y_i * origin_x_inc, src_tl.y + y_i * origin_y_inc);
APoint const rot_origin(tl.x + y_i * rotated_x_inc, tl.y + y_i * rotated_y_inc);
APoint previous = rot_origin;
for (int x_i = 0; x_i <= (int) line_nb_steps; ++x_i)
{
DPoint const src_rotated_point(src_origin.x + x_i * line_x_inc, src_origin.y + x_i * line_y_inc);
APoint const rot_point(rot_origin.x + x_i * bresenham.x, rot_origin.y + x_i * bresenham.y);
// if (y_i < 2 && (x_i == 0 || x_i == line_nb_steps - 1))
// {
// cout << " y_i[" << y_i << "] x_i[" << x_i << "]" << endl;
// cout << " src origin: " << src_origin << endl;
// cout << " src rotated point: " << src_rotated_point << endl;
// cout << " rotated origin: " << rot_origin << endl;
// cout << " rotated point: " << rot_point << endl;
// }
// TODO: Interpolation would be done here
APoint src_p(src_rotated_point.x, src_rotated_point.y);
uint8_t r = 0;
uint8_t g = 0;
uint8_t b = 0;
// TODO: bypass variables, access src pixels
src.get_pixel(src_p, r, g, b);
rotated.set_pixel(rot_point, r, g, b);
// Fill missing points, created by interpolation
if (previous.x != rot_point.x && previous.y != rot_point.y)
{
rotated.set_pixel(APoint(rot_point.x, previous.y), r, g, b);
}
previous = rot_point;
}
}
return rotated;
}
//
//
// Check
//
bool check_points()
{
Image five(5, 5);
Point origin(0, 0);
DPoint d1 = convert_grid_coord(five, origin);
assert(d1.x == -2);
assert(d1.y == -2);
return true;
}
bool check_trigo()
{
Image square(500, 500);
double const ratio = compute_ratio(square);
double const sigma = 1.0e-2;
if (!fequal(ratio, 1 / 707.106, sigma))
{
cerr << __LINE__ << " | Invalid ratio: " << ratio << " != " << 1 / 707.106 << endl;
return false;
}
// Check that the origin of a square image is at sqrt(2) / 2
double const angle = convert_radian(square, Point(0, 0), ratio);
if (!fequal(angle, 3 * M_PI / 4, sigma))
{
cerr << __LINE__ << " | Invalid angle value: " << angle << " != " << 3 * M_PI / 4 << endl;
return false;
}
// Check that we can reverse the origin point.
DPoint const abs_reverse_point = convert_abs_coord(angle, ratio);
APoint const reverse_point = convert_img_coord(square, abs_reverse_point);
if (!fequal(0.0, reverse_point.x, sigma)
|| !fequal(0.0, reverse_point.y, sigma))
{
cerr << __LINE__ << "Reverse origin fail" << endl;
cerr << " " << reverse_point << " != (0, 0)" << endl;
cerr << " abs point " << abs_reverse_point << 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);
if (!fequal(w, square.width * sqrt(2), sigma * square.width)
|| !fequal(h, square.height * sqrt(2), sigma * square.height))
{
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);
DPoint const a_p45 = convert_abs_coord(angle + rotation, ratio);
APoint const p45 = convert_img_coord(rotated, a_p45);
if (!fequal(0, p45.x, sigma))
{
cerr << __LINE__ << " > Rotation origin by 45 degrees:" << endl;
cerr << " invalid x value: " << p45.x << " != " << 0 << endl;
cerr << " absolute point: " << a_p45 << endl;
cerr << " relative point: " << p45 << endl;
return false;
}
if (!fequal(p45.y, (h - 1) / 2.0f, sigma))
{
cerr << __LINE__ << " > Rotation origin by 45 degrees:" << endl;
cerr << "Invalid y value: " << p45.y << " != " << (h - 1) / 2.0f << endl;
cerr << " absolute point: " << a_p45 << endl;
cerr << " relative point: " << p45 << endl;
return false;
}
// Polar coordinates
{
DPoint const d(-42.5, 37.5);
double angle = 0;
double dist = 0;
convert_abs_to_polar_coord(d, angle, dist);
DPoint const reversed = convert_polar_to_grid_coord(angle, dist);
if (!fequal(d.x, reversed.x, sigma)
|| !fequal(d.y, reversed.y, sigma))
{
cerr << __LINE__ << " > Reverse polar coordinates:" << endl;
cerr << reversed << " != " << d << endl;
cerr << "polar (" << angle << ", " << dist << ")" << endl;
return false;
}
}
return true;
}
void check_lines()
{
Image const square(500, 500);
draw_outline(square, 5, "square");
draw_outline(square, 12, "square");
draw_outline(square, 22, "square");
draw_outline(square, 33, "square");
draw_outline(square, 45, "square");
draw_outline(square, 60, "square");
draw_outline(square, 75, "square");
draw_outline(square, 90, "square");
Image const rect1(640, 480);
draw_outline(rect1, 22, "rect1");
draw_outline(rect1, 33, "rect1");
draw_outline(rect1, 45, "rect1");
draw_outline(rect1, 90, "rect1");
}
bool check_90(string const& path)
{
Image const src(path);
Image const rotated = rotate(src, 90);
for (unsigned int y = 0; y < rotated.height; ++y)
{
for (unsigned int x = 0; x < rotated.width; ++x)
{
unsigned rot_index = y * rotated.width + x;
unsigned src_index = x * src.width + (rotated.width - 1 - y);
if (rotated.r_chan[rot_index] != src.r_chan[src_index])
return false;
if (rotated.g_chan[rot_index] != src.g_chan[src_index])
return false;
if (rotated.b_chan[rot_index] != src.b_chan[src_index])
return false;
}
}
return true;
}
//
//
// Main
//
int main(int argc, char* argv[])
{
if (argc < 2)
{
cout << "Usage: " << argv[0] << " image.ppm" << endl;
return 1;
}
bool perform_check = true;
if (perform_check)
{
if (!check_points())
return 1;
if (!check_trigo())
return 1;
//check_lines();
if (false && !check_90(argv[1]))
{
cerr << __LINE__ << " | 90 degrees check failed" << endl;
return 1;
}
}
Image img(argv[1]);
for (double rotation = 0; rotation <= 360; rotation += 5)
{
auto const before = chrono::high_resolution_clock::now();
Image rotated = rotate(img, rotation);
auto const after = chrono::high_resolution_clock::now();
auto const duration_ms = std::chrono::duration_cast<std::chrono::milliseconds>(after - before);
cout << "rotate(" << rotation << "): " << duration_ms.count() << " ms" << endl;
stringstream filename;
filename << "rotated_";
if (rotation < 100)
filename << "0";
if (rotation < 10)
filename << "0";
filename << rotation << ".ppm";
rotated.save(filename.str());
}
return 0;
}