/* Copyright (C) 2013 Karl Phillip Buhr <karlphillip@gmail.com>

*

* This work is licensed under the Creative Commons Attribution-ShareAlike License.

* To view a copy of this license, visit:

* https://creativecommons.org/licenses/by-sa/2.5/legalcode

*

* Or to read the human-readable summary of the license:

* https://creativecommons.org/licenses/by-sa/2.5/

*/

#include "widget.h"

#ifndef __APPLE__

#include <GL/GLU.h>

#else

#include <glu.h>

#endif

#include <iostream>

#include <QKeyEvent>

#include <QTimer>

GLWidget::GLWidget(QWidget *parent)

: QGLWidget(parent)

{

_width = 0;

_height = 0;

_texture = 0;

_fps = 0;

}

GLWidget::~GLWidget()

{

glDeleteTextures(1, &_texture);

}

void GLWidget::_tick()

{

// triggers paintGL()

update();

// Set timer according to FPS

QTimer::singleShot(1000/_fps, this, SLOT(_tick()));

}

void GLWidget::initializeGL()

{

// Set clear color as black

glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

// Select pixel storage mode used by glTexImage2D

glPixelStorei (GL_UNPACK_ALIGNMENT, 1);

// Create the texture

glGenTextures(1, &_texture);

/* Open default camera device */

cv_capture.open(0);

if (!cv_capture.isOpened())

{

std::cout << "GLWidget::initializeGL: !!! Failed to open camera" << std::endl;

return;

}

// Retrieve FPS from the camera

_fps = cv_capture.get(CV_CAP_PROP_FPS);

if (!_fps) // if the function fails, fps is set to 15

_fps = 15;

std::cout << "GLWidget::initializeGL: " << _fps << " fps" << std::endl;

/* Start the timer */

_tick();

}

void GLWidget::paintGL()

{

// Clear the screen and depth buffer (with black)

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// Select the model view matrix and reset it

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

glTranslatef(0.0f, 0.0f, 0.0f);

// Abort drawing if OpenCV was unable to open the camera

if (!cv_capture.isOpened())

{

std::cout << "GLWidget::paintGL: !!! Failed to open camera" << std::endl;

return;

}

// Note: trying to retrieve more frames than the camera can give you

// will make the output video blink a lot.

cv_capture >> cv_frame;

if (cv_frame.empty())

{

std::cout << "GLWidget::paintGL: !!! Failed to retrieve frame" << std::endl;

return;

}

cv::cvtColor(cv_frame, cv_frame, CV_BGR2RGBA);

glEnable(GL_TEXTURE_RECTANGLE_ARB);

// Typical texture generation using data from the bitmap

glBindTexture(GL_TEXTURE_RECTANGLE_ARB, _texture);

// Transfer image data to the GPU

glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0,

GL_RGBA, cv_frame.cols, cv_frame.rows, 0,

GL_RGBA, GL_UNSIGNED_BYTE, cv_frame.data);

if (glGetError() != GL_NO_ERROR)

{

std::cout << "GLWidget::paintGL: !!! Failed glTexImage2D" << std::endl;

}

// Draw a 2D face with texture

glBegin(GL_QUADS);

glTexCoord2f(0, 0); glVertex2f(1.0, 1.0);

glTexCoord2f(cv_frame.cols, 0); glVertex2f(-1.0, 1.0);

glTexCoord2f(cv_frame.cols, cv_frame.rows); glVertex2f(-1.0, -1.0);

glTexCoord2f(0, cv_frame.rows); glVertex2f(1.0, -1.0);

glEnd();

glDisable(GL_TEXTURE_RECTANGLE_ARB);

}

void GLWidget::resizeGL( int w, int h)

{

_width = w;

_height = h;

glViewport(0, 0, w, h);

glMatrixMode(GL_PROJECTION); // Select the projection matrix

glLoadIdentity(); // Reset the projection matrix

if (h == 0) // Calculate aspect ratio of the window

gluPerspective(60, (float) w, 1.0, 50.0);

else

gluPerspective(60, (float) w / (float) h, 1.0, 50.0);

gluLookAt(0.0, 0.0, 2.0, // eye

0.0, 0.0, 0.0, // center

0.0, 1.0, 0.0); // up

glMatrixMode(GL_MODELVIEW); // Select the model view matrix

glLoadIdentity(); // Reset the model view matrix

}