I am trying to draw a bezier curve which uses 4 control points to draw a curve. However when I run my program, after 4 clicks with mouse I only see one pixel being drawn, am I missing something in my code? How can I get this to work properly?
void MyWindow::mousePressEvent(QMouseEvent *event)
{
if(event->button() == Qt::LeftButton)
{
x0 = event->x();
y0 = event->y();
point.setX(x0);
point.setY(y0);
std::vector<QPoint> myv;
myv.push_back(point);
counter+=1;
std::cout<<counter<<std::endl;
if(counter%4==0) {
drawBezier(myv[0], myv[1], myv[2], myv[3]);
}
}
update();
}
myv is local variable and you dont save its state to the new mousePressEvent
Get some "debug" info and see what you receive in drawBezier function.
Related
I am currently working on a project that I use C++, OpenGL, Qt 5.9.2 and Microsoft Visual Studio Professional 2015 on a 64 bit Operating System, Windows 10 Pro.
I have a user interface that I have created and in that user interface, there is a QGLWidget, that I am using for draw processes, with other widgets like push buttons and a dockWidget. I have a class Ball and it has variables(distance(double) and angle(int)) that determines where an instance of that Ball is going to be drawn inside the QGLWidget. Ball class has got 2 more variables that is, id(int), model(String) and year(int) Every other draw process draws lines except Ball drawings.
Drawings are 2 dimensional.
Every Ball has the same color(rgb)!
First problem: I want to left click to one of the Ball instances and I want to display it's id, model and year at The dockWidget.
Second Problem: While doing the stuff that I have mentioned at the First Problem section. I want the cursor image to change while hovering above any of the Ball instances, and change back to default Windows mouse cursor while not.
I have created a function that checks if the MouseEvent is LeftClick:
void DisplayManager::mousePressEvent(QMouseEvent* ev) {
if (ev->buttons() & Qt::LeftButton) { // Balls Are Green
if(// CHECK IF THERE IS A BALL AT THE CLICKED COORDINATES) {
// DISPLAY THE X and Y OF THE BALL AT THE DOCK WIDGET
}
}
}
This is my initializeGL function: (DisplayManager is the name of my QGLWidget)
void DisplayManager::initializeGL() {
glEnable(GL_COLOR_MATERIAL); // Enables the changing of the draw color with glColor() functions
glColor3f(0.0, 1.0, 0.0);
glEnable(GL_DEPTH_TEST);
glClearColor(0, 0, 0, 1); //sets a black background 1 0 0 1
}
On the basis this is a Picking problem and there are several information about it at the internet but I am not using GLUT and I am not using any shader. So in the light of all these I was unable to find any effective solution or clue about how can I accomplish all that I want.
I would be really glad if someone could help me with at least one of these problems.
I have currently finished working with the project. I thought that I should provide an answer to my question in case someone with a similar problem comes across with my question in the future.
void DisplayManager::mousePressEvent(QMouseEvent* ev) {
// The processes that are being executed after a left mouse button click on the DisplayManager.
if (ev->buttons() & Qt::LeftButton) {
double aspectRatio = openGLWidgetWidth / openGLWidgetHeight;
int xOfClicked = ev->x() - (openGLWidgetWidth / 2);
int yOfClicked = - (ev->y() - (openGLWidgetHeight / 2));
// The variable to be used for calculating fault tolerance of the click event.
int distanceBetweenPressAndDraw = 0;
// Executes the processes inside for every ball in vector.
for (int i = 0; i < ballVector.length(); i++) {
// Calculates the screen coordinates of the i'th ball.
int rangeOfBallInScreenDistance = rangeToScreenDistance(ballVector.at(i).range);
double screenXOfBall = rangeOfBallInScreenDistance * sin(ballVector.at(i).degree * DEGTORAD);
double screenYOfBall = rangeOfBallInScreenDistance * cos(ballVector.at(i).degree * DEGTORAD);
// Calculates the distance between pressed position and the i'th ball according to the screen coordinates.
distanceBetweenPressAndDraw = sqrt(pow((screenXOfBall - xOfClicked), 2) + pow((screenYOfBall - yOfClicked), 2));
// Decides if the clicked position is a ball (considering the fault tolerance).
if (distanceBetweenPressAndDraw < 10) {
emit printXY(QPointF(xOfClicked, yOfClicked)); // Prints the screen coordinates of the clicked positions (At the Dock Widget inside Main Window).
}
}
}
}
This was the solution for my First Problem. I would be glad though if someone could answer my Second problem in a comment or answer somehow.
I created my own classes (view and scene) to display image and objects I added to it, even got zoom in/out function implemented to my view, but now I have to add new functionality and I don't even know how to start looking for it.
Whenever I press the scroll button of my mouse and hold it - I wish to move around the scene, to see different parts of it - just like I would with sliders. It is supposed to be similar to any other program allowing to zoom in/out to image and move around zoomed picture to see different parts of it.
Unfortunately - I don't even know how to look for some basic, because "moving" and similar refer to dragging objects around.
EDIT 1
void CustomGraphicView::mouseMoveEvent(QMouseEvent *event)
{
if(event->buttons() == Qt::MidButton)
{
setTransformationAnchor(QGraphicsView::AnchorUnderMouse);
translate(event->x(),event->y());
}
}
Tried this - but it is working in reverse.
I suppose you know how to handle events using Qt.
So, to translate (move) your view use the QGraphicsView::translate() method.
EDIT
How to use it:
void CustomGraphicsView::mousePressEvent(QMouseEvent* event)
{
if (e->button() == Qt::MiddleButton)
{
// Store original position.
m_originX = event->x();
m_originY = event->y();
}
}
void CustomGraphicsView::mouseMoveEvent(QMouseEvent* event)
{
if (e->buttons() & Qt::MidButton)
{
QPointF oldp = mapToScene(m_originX, m_originY);
QPointF newP = mapToScene(event->pos());
QPointF translation = newp - oldp;
translate(translation.x(), translation.y());
m_originX = event->x();
m_originY = event->y();
}
}
I made a heap on console. I've done all coding. Now I just need to show the heap tree on a drawing board. I am new to MFC and learned some basics like using a pDC pointer to draw nodes. Like pDC->ellipse(int x,int x2,int y,int y2). However I don't get how I will be able to show a complete tree on the board.
void CAst3View::OnDraw(CDC* pDC)
{
CAst3Doc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
if(a.control_draw == true)
{
pDC->Ellipse(100, 100 ,500,500);
}
//if (a.height!=0)
//{
// pDC->Ellipse(100, 100 ,500,500);
//}
// TODO: add draw code for native data here
}
This gives me one circle on the drawing board.
The Ellipse function is used to draw a circle. To draw a complete tree, you may need to change the x- and y- coordinates and keep drawing the circle, then connect each circle using the LineTo function.
Related post which may help you: Tree Circle Draw Control
I am having trouble with a project of mine. I am trying to draw in an render-area a course for the cars (a street) which can contain both straight lines and curves. For that I was thinking of primarily drawing the lines and then with the mouse selecting one line and transforming it into a curve by moving the mouse (a curve which has as peek the point on the line selected by the mouse). Until now I only managed to draw points in the render area and automatically generate lines between these points, but I am not sure about how to transform the line into a curve with the mouse.
My code until now is:
renderarea.cpp:
RenderArea::RenderArea(QWidget *parent)
: QWidget(parent)
{
setBackgroundRole(QPalette::Base);
setAutoFillBackground(true);
}
void RenderArea::mousePressEvent(QMouseEvent *e)
{
point = e->pos();
updateList(point);
this->update();
}
void RenderArea::updateList(const QPoint& p)
{
Point point;
point.point = p;
list.append(point);
if (list.count()>1)
lineAdded(point);
}
void RenderArea::lineAdded(const Point &p)
{
Line temp;
temp.endPoint = p;
temp.startPoint = list.at(list.count() - 2);
lines.append(temp);
}
void RenderArea::paintEvent(QPaintEvent * /* event */)
{
int i;
QPainter painter(this);
painter.setPen(QPen(Qt::black,2));
for (i = 0; i < list.size(); ++i)
painter.drawPoint(list[i].point);
for (i = 0; i < lines.size(); ++i)
painter.drawLine(lines[i].startPoint.point, lines[i].endPoint.point);
}
Hope you can help me. Thanks in advance.
Have some UI (right click?) that changes the line segment to Besier curve. Then control the shape of the curve by dragging handles (which you will need to provide). Another right click changes the curve back to segment.
I'm using GLUT and developing a FPS game. I need a way to trap the mouse so that the camera continues to move because right now when the mouse position exceeds the monitor limit, there is no way to calculate change in X or change in Y. How can I 'trap' the mouse with GLUT?
Thanks
I'd recommend using a ready-made engine like OGRE 3D instead, but if you really want to reinvent the wheel, here's how...
In all cases I'm aware of, PC FPS games "trap" the pointer by registering a mouse motion callback, noting the relative motion, and then warping the pointer back to the center of the window.
Here's some code I wrote to add mouse input to a sample ping-pong table in an OpenGL with C++ course a year or two ago:
void resetPointer() {
glutWarpPointer(TABLE_X/2, TABLE_Y/2);
lastMousePos = TABLE_Y/2;
}
void mouseFunc(int sx, int sy) {
if (!started) { return; }
int vertMotion = lastMousePos - sy;
lastMousePos = sy;
player1.move(vertMotion);
// Keep the pointer from leaving the window.
if (fabs(TABLE_X/2 - sx) > 25 || fabs(TABLE_Y/2 - sy) > 25) {
resetPointer();
}
}
// This goes in with your "start new game" code if you want a menu
resetPointer();
glutSetCursor(GLUT_CURSOR_NONE);
glutPassiveMotionFunc(mouseFunc);
It only tracks vertical motion, but adding horizontal is trivial.