Drawing Dice in a Windows C++ program? - c++

Question

We just started learning windows programming in C++. We have to make a program that has 4 die on the screen, and when the user presses 'SpaceBar', the die roll, or the number of dots on the die change randomly. Our professor hasent given us a lot of information, so I am kind of just looking for some direction.
Right now, I have 4 squares drawn on the screen, made with the Rectangle() function.
Rectangle(hDC,30,100,130,200);
Rectangle(hDC,180,100,280,200);
Rectangle(hDC,330,100,430,200);
Rectangle(hDC,480,100,580,200);
My question is 1) how would I go about drawing dots on these 'squares' and not on the 'screen'. So if I move the die upwards, the dots move with the square and dont just stay stationed painted on the screen. And 2.) How would I go about making those dots randomly change when spacebar is pressed (simulating that they have been rolled)?
Just looking for some direction, thanks.

Answer 1

1)
You will still have to draw them on the screen, but you can structure your program to realize the dots as part of the square.
void moveSquare()
{
//change square position
//change dots positions the same as you changed the square
}
2)
You can capture keypresses in your window with the WM_KEYDOWN and WM_KEYUP messages, or the WM_CHAR message. Just start a chain of changing how many dots are supposed to appear on the die when space is pressed (SetTimer could be handy), and let WM_PAINT do the work of painting the dots (or call something to calculate the positions of the dots, and let WM_PAINT loop through each dot it needs to draw.
void OnSpacePressed()
{
//start changing dots every so often, handled elsewhere
//maybe check if finished rolling before doing so
}
void calculateDotPositions()
{
switch (numberOfDots) {...} //hint: use the square as a reference point
}
void OnPaint()
{
//paint each sqaure
//paint each dot in the correct position, which should be updated with square
}
void OnChangeDots()
{
//change number of dots
//also start a new change to happen later if not done rolling
}
For drawing dots, use Warren P's reference link.

Answer 2

Another method is to create a bitmap or picture in memory. One for each of the 6 faces of the die. The objective here is to copy the bitmaps to the screen, rather than having to redraw them each time. Research "bitmap", and "bitblt".

Answer 3

You should make a routine that draws a die at the origin, offset by given coordinates. I'm not familiar with the particular library you are using, so I don't know what hDC is, but it should look something like the following.
void drawDie(HDC hDC, int xCoord, int yCoord, int dieValue)
{
Rectangle(hDC, -50 + xCoord, -50 + yCoord, 50 + xCoord, 50 + yCoord);
// draw some number of circles specified by dieValue at appropriate coordinates
// translated by xCoord and yCoord arguments
}
Then you can just redraw dice over your previous ones if you want them to change.