Program giving lots of hiccups, CPU processing is low.

[D.V.D]

So I made a program that draws little squares that bounce of walls for eternity. Its not a very intensive program, when it's running, the CPU usage is 5-7% with other stuff running. The program runs through a main loop where box positions are updated and when the box hits a wall, its angle is changed and the loop steps back a index so it can rerun the index of the knocked back box to make it move. The problem is, when the box hits a wall, it stops for a moment before moving again. The other boxes are still moving however and there seems to be some times where every box stops moving for a moment before it hits a wall. I can't seem to find the problem for this as each box should be moved at the same pace. The actual window is a non modified visual studio C++ template for a window with my steup function called when paint is enabled. Here's the code:

Box Class.h

#include "stdafx.h"
#include <cmath>

class Box {

public:

	// Box Image
	COLORREF col;
	int radius;

	// Box Properties
	float angle;
	int speed;
	int x;
	int y;
	/*
	Box (int,int,int,float,COLORREF col);
	~Box ();
	void draw (HDC);
	*/
};

Box CreateBox (int,int,int,float,COLORREF col);
void DrawBox (HDC,Box);
void ClearBox (HDC,Box);

Box Class.cpp

#include "stdafx.h"
#include "Box Class.h"

COLORREF BOX_CLASS_CLEAR = RGB(255,255,255);
Box CreateBox (int newx,int newy,int newspeed,float newang,COLORREF col) {
	Box New = Box();
	New.x=newx;
	New.y=newy;
	New.speed=newspeed;
	New.angle=newang;
	New.radius=4;
	return New;
}

void ClearBox (HDC hdc,Box b) {
	COLORREF clear = RGB(255,255,255);
	for (short i=0; i < b.radius; i++) {
		for (short t=0; t < b.radius; t++) {
			SetPixel(hdc,b.x+i,b.y+t,clear);
		}
	}
}

void DrawBox (HDC hdc,Box b) {
	for (short i=0; i < b.radius; i++) {
		for (short t=0; t < b.radius; t++) {
			SetPixel(hdc,b.x+i,b.y+t,b.col);
		}
	}
}

Bouncy Boxes.h

#include "stdafx.h"
#include "Box Class.h"
#include <stdio.h>
#include <stdlib.h>
#include <ctime>

void setup (HDC);
void moveboxes (HDC);

Bouncy Boxes.cpp

#include "stdafx.h"
#include "Bouncy Boxes.h"

const int NUM_BOXES=5;
Box BOX_LIST [NUM_BOXES];

const int mapx=300;
const int mapy=300;

float DEGTORAD = 0.0019;

void setup (HDC hdc) {
	COLORREF col = RGB(100,0,0);

	srand(time(0));

	for (short i=0; i < NUM_BOXES; i++) {
		BOX_LIST[i]=CreateBox (rand()&300,rand()&300,3,rand()&360,col);
	}
	for (short i=0; i < 20; ) {
		moveboxes(hdc);
		Sleep(10);
	}
}

void moveboxes (HDC hdc) {
	int newx,newy;
	for (short i=0; i < NUM_BOXES; i++) {
		newx=int(BOX_LIST[i].x+BOX_LIST[i].speed*cos(float(BOX_LIST[i].angle*DEGTORAD)));
		newy=int(BOX_LIST[i].y+BOX_LIST[i].speed*sin(float(BOX_LIST[i].angle*DEGTORAD)));
		if (newx-1 < 0 || newy-1 < 0 ) {
			BOX_LIST[i].angle+=45;
			i-=1;
			return;
		}
		else if ( newx-1 > mapx || newy-1 > mapy) {
			BOX_LIST[i].angle+=45;
			i-=1;
			return;
		}
		else {
			ClearBox(hdc,BOX_LIST[i]);
			BOX_LIST[i].x=newx;
			BOX_LIST[i].y=newy;
			DrawBox(hdc,BOX_LIST[i]);
		}
	}
}

 

[s3rius]

Why do you have this loop:

for (short i=0; i < 20; ) {
	moveboxes(hdc);
	Sleep(10);
}

When you also have a loop in moveboxes? And is that setup() called periodically by the application or just once? (I haven't worked with this framework).

 

[D.V.D]

Its called once, its just for test so for my program to end at some point or another, it will only move every box however many amount of times I specify, right now its infinite however. The loop in moveboxes is to move all the boxes at once so if you have 5 boxes in the BOX_LIST, calling moveboxes will move all 5 of those boxes.

 

[s3rius]

Ah, got it. You just used the wrong keyword:

if (newx-1 < 0 || newy-1 < 0 ) {
	BOX_LIST[i].angle+=45;
	i-=1;
	return;
else if ( newx-1 > mapx || newy-1 > mapy) {
	BOX_LIST[i].angle+=45;
	i-=1;
	return;
}
}

The "return" will cancel the entire loop and stop the function, which makes every box that's yet to be moved (inclusing the one that collides) stop. Either needs to be a "continue" or you leave it out completely (there's only the if-statement in your loop so it would jump to the next iteration one way or another).
(Interesting way to solve this via i-=1 btw )

 

[D.V.D]

LOL my mistake Thanks a lot +rep