## Recommended Posts

well I have decided to finish my breakout game using opengl and c++. I am still stuck on how to get the ball to bounce off the brick and get it to disappear. Then when it is removed I want the ball to pass through the space where the brick was. Please don't give me a lot of code. Also I am using magic numbers for now. Here is just a little bit of code. [code]if(x>=3.0f && x<=5.0f && y>=3.5f && y<=4.0f) { ystep = -ystep; g_bBlock[4].m_bActive_three=false; }[/code] well this code checks for a brick and then switches the ball's velocity and then turns off the brick. but it still bounces off where the brick was. I know I have asked this question before but I would like a fresh perspective. I am doing my best to finish this project.

##### Share on other sites
You already have an array with a bool inside that tells if a brick is active or not. You only do the collision check if the brick is still active.

##### Share on other sites

well I have decided to finish my breakout game using opengl and c++. I am still stuck on how to get the ball to bounce off the brick and get it to disappear. Then when it is removed I want the ball to pass through the space where the brick was. Please don't give me a lot of code. Also I am using magic numbers for now. Here is just a little bit of code.

if(x>=3.0f && x<=5.0f && y>=3.5f && y<=4.0f)
{
ystep = -ystep;
g_bBlock[4].m_bActive_three=false;
}
well this code checks for a brick and then switches the ball's velocity and then turns off the brick. but it still bounces off where the brick was. I know I have asked this question before but I would like a fresh perspective. I am doing my best to finish this project.

simply check that the brick is still valid when your comparing to hit it, like so:

if(x>=3.0f && x<=5.0f && y>=3.5f && y<=4.0f && g_bBlock[4].m_bActive_three==true) {
ystep = -ystep;
g_bBlock[4].m_bActive_three=false;
}

your naming convention is a bit odd(_three?)

edit: also, just to toss this out their for thought: what happens when your ball impacts the block along the side's rather than top or bottom?

Edited by slicer4ever

##### Share on other sites

As Endurion pointed out just use the bool in the condition for collision.

if(g_bBlock[4].m_bActive_three==true)
{
if(x>=3.0f && x<=5.0f && y>=3.5f && y<=4.0f)
{
ystep = -ystep;
g_bBlock[4].m_bActive_three=false;
}
}

But trust me, there are much more efficient ways of detecting collision and removing the blocks.  The one you are using is probably the easiest but not accurate in many cases.

Edited by Sam Sandeep

##### Share on other sites

I would agree with Endurion and Sam Sandeep.  Sounds like you are calculating collision even if the brick is "turned off".  I would also like to add why are you keeping the brick in memory at all?  If it is "destroyed" once the ball makes impact why don't you just completely remove it from memory?  Remove it from the active collection, free up memory don't have to waste time calculating for collision on it (even if it is turned off).

##### Share on other sites
Man, I really hate to be a dick, but...

http://www.gamedev.net/topic/636083-little-more-help/
http://www.gamedev.net/topic/635556-little-help/
http://www.gamedev.net/topic/635213-collision-detection/
http://www.gamedev.net/topic/634727-breakout-game/
http://www.gamedev.net/topic/633265-collision-detection/
http://www.gamedev.net/topic/625158-collision-question/
http://www.gamedev.net/topic/622320-collision-code/
http://www.gamedev.net/topic/622165-2d-collision/

The list goes on.

You have this habit of posting a question, getting some answers, maybe posting some final response like "Wow, that is a lot of code", then disappearing for a few weeks. When you come back, you are asking the same exact questions as before. I really hate discouraging anyone, but are you really certain that programming is for you? It just doesn't seem like you are actually learning anything or making any progress at all. There is nothing wrong with not being able to program, but there is something wrong with continuing to ask the same questions over and over, wasting the time and effort of everyone who has posted in your many threads trying to help you out.

##### Share on other sites

Sometimes I feel like Phil is trolling us, and he just chuckles when we post a lot of code to help him.

Then I think maybe he's just struggling very hard and just can't "get it".  It happens.  At least he's trying hard (if he's not trolling)

##### Share on other sites
I am really trying hard, I really like programming but I am kind of slow.

##### Share on other sites
ok blanc I am not the best programmer but I do enjoy it. I graduated from college with a b.s. in c.s. in 2005. I have actually learned a lot since then but there always seems to be more to learn.

##### Share on other sites
I graduated from college with a b.s. in c.s. in 2005.

Which college?

##### Share on other sites

[code]

struct TBrick {
int XPosition;
int YPosition;
int XSize;
int YSize;
uint32_t Color;
uint32_t ActiveState;  // 0 is deactive; If it takes multiple hits to kill a brick, it can start greater than 1
};

struct TBall {
int XPosition;
int YPosition;
int XSize;
int YSize;
int XSpeed;
int YSpeed;
};

#define BRICK_COLUMNS 20 // how many bricks in a column
#define BRICK_ROWS 10 // how many bricks ina  row
#define BRICK_START_X 60 // Where the bricks start on the x-axis
#define BRICK_START_Y 40 // Where the bricks start on the y-axis
#define BRICK_WIDTH 30 // brick width in pixels
#define BRICK_HEIGHT 15 // brickheight in pixels

// make this a global array
TBrick BrickArray[BRICK_COLUMNS][BRICK_ROWS];

// Initialize the Brick Array somewhere at the start of your code
for (int x = 0; x < BRICK_COLUMNS; x++) {
for (int y = 0; y < BRICK_ROWS; y++) {
BrickArray[x][y].XSize = BRICK_WIDTH;
BrickArray[x][y].YSize = BRICK_HEIGHT;
BrickArray[x][y].XLocation = BRICK_START_X + x*BRICK_WIDTH;
BrickArray[x][y].YLocation = BRICK_START_Y + y*BRICK_HEIGHT;
BrickArray[x][y].Color = 0xFFFFFFFF; // white
BrickArray[x][y].ActiveState = 1; // 1 hit to turn off brick
}
}

// in main loop do this:
// move Ball in X direction, then check collision
Ball.XLocation += Ball.XSpeed;
if (CheckCollision(Ball)) {
// The ball hit something, move to original location and negate X speed
Ball.XLocation -= Ball.XSpeed;
Ball.XSpeed = -Ball.XSpeed;
}

// Do same for Y movement
Ball.YLocation += Ball.YSpeed;
if (CheckCollision(Ball)) {
// The ball hit something, move to original location and negate Y speed
Ball.YLocation -= Ball.YSpeed;
Ball.YSpeed = -Ball.YSpeed;
}

RenderBricks();

... // the rest of the main loop

// Here are those functions
bool CheckCollisions(TBall ball)
{
// loop through every brick and see if we've hit it
for (int x = 0; x < BRICK_COLUMNS; x++) {
for (int y = 0; y < BRICK_ROWS; y++) {
// Only check against bricks that are active
if (BrickArray[x][y].ActiveState > 0) {
if (ball.XLocation + ball.XSize < BrickArray[x][y].XLocation ||
ball.YLocation  + ball.YSize < BrickArray[x][y].YLocation ||
ball.XLocation > BrickArray[x][y].XLocation + BrickArray[x][y].XSize ||
ball.YLocation  < BrickArray[x][y].YLocation + BrickArray[x][y].YSize) {
// It's collided wit brick, decrment Active state of brick and return true
BrickArray[x][y].ActiveState--;
return true;
}
}
}

// Check if we've hit the paddle and
// Check if we've hit the wall (I'll leave this up to you)
}

// This Draws the bricks
void RenderBricks()
{
// loop through every brick and draw if active
for (int x = 0; x < BRICK_COLUMNS; x++) {
for (int y = 0; y < BRICK_ROWS; y++) {
if (BrickArray[x][y].ActiveState > 0) {
// Call you GL draw function, whatever it is.  it would be simple to do in SFML however
GlDrawRect(BrickArray[x][y].XLocation, BrickArray[x][y].YLocation,
BrickArray[x][y].XSize, BrickArray[x][y].YSize, BrickArray[x][y].Color);
}
}
}
}
[/code]

It gives a general idea of how to encapsulate brick's and the ball into it's own structure, and shows how to handle collisions and rendering.

Edited by BeerNutts

##### Share on other sites
I graduated from California state san bernardino

##### Share on other sites
thanks beer for the code, so how should I digest the code you have given me, I tend to learn more with smaller amounts of code.

##### Share on other sites


struct TBrick {
int XPosition;
int YPosition;
int XSize;
int YSize;
uint32_t Color;
uint32_t ActiveState;  // 0 is deactive; If it takes multiple hits to kill a brick, it can start greater than 1
};

struct TBall {
int XPosition;
int YPosition;
int XSize;
int YSize;
int XSpeed;
int YSpeed;
};


Do you understand why that does, and understand why they are group'd together?

Then, look at the array of bricks, and the loop that initializes the brick array:

#define BRICK_COLUMNS 20 // how many bricks in a column
#define BRICK_ROWS 10 // how many bricks ina  row
#define BRICK_START_X 60 // Where the bricks start on the x-axis
#define BRICK_START_Y 40 // Where the bricks start on the y-axis
#define BRICK_WIDTH 30 // brick width in pixels
#define BRICK_HEIGHT 15 // brickheight in pixels

// make this a global array
TBrick BrickArray[BRICK_COLUMNS][BRICK_ROWS];

// Initialize the Brick Array somewhere at the start of your code
for (int x = 0; x < BRICK_COLUMNS; x++) {
for (int y = 0; y < BRICK_ROWS; y++) {
BrickArray[x][y].XSize = BRICK_WIDTH;
BrickArray[x][y].YSize = BRICK_HEIGHT;
BrickArray[x][y].XLocation = BRICK_START_X + x*BRICK_WIDTH;
BrickArray[x][y].YLocation = BRICK_START_Y + y*BRICK_HEIGHT;
BrickArray[x][y].Color = 0xFFFFFFFF; // white
BrickArray[x][y].ActiveState = 1; // 1 hit to turn off brick
}
}


Do you know what that is doing?  And slowly go form there.  Just break up " a lot of code" into small pieces of code.  read the comments in the code.  It explains every thing.

If you have questions about certain parts of it, ask about it.  it's better than staring at something not understanding what it's doing.

I graduated from California state san bernardino

Really?  BS in CS?  Do you have a job as a programmer now?

Edited by BeerNutts

##### Share on other sites
yes a bachelors in computer science, I am unemployed at the moment, although I have had some job interviews last year. I am still looking for work right now.

##### Share on other sites
yeah!! thanks for all the help, I finally solved the collision problem with the ball and bricks.

##### Share on other sites
yeah!! thanks for all the help, I finally solved the collision problem with the ball and bricks.

Show us your solution.  I've heard you say that before, but you come back and ask the question again.

##### Share on other sites
well here it is [code]if( g_bBlock[4].m_bActive_three==true) { if(x>=3.0f && x<=5.0f && y>=3.5f && y<=4.0f) { ystep = -ystep; bricks[2][4]=true; g_bBlock[4].m_bActive_three=false; } }[/code]

##### Share on other sites

well here it is

if(	g_bBlock[4].m_bActive_three==true)
{
if(x>=3.0f && x<=5.0f && y>=3.5f && y<=4.0f)
{
ystep = -ystep;
bricks[2][4]=true;
g_bBlock[4].m_bActive_three=false;
}
}

Sigh.

...

Just...Sigh.

I give up.  Good luck to you.

sorry beer

##### Share on other sites
don't give up on me yet

##### Share on other sites
well I am using the code that sam gave to me.

##### Share on other sites

well here it is

if(	g_bBlock[4].m_bActive_three==true)
{
if(x>=3.0f && x<=5.0f && y>=3.5f && y<=4.0f)
{
ystep = -ystep;
bricks[2][4]=true;
g_bBlock[4].m_bActive_three=false;
}
}

So I want to chime in on this, maybe a modification of your code into something that resembles the naming conventions of BeerNutts (will remove magic numbers/ambiguity) might help you to understand:

// Start a loop to loop through all the block
for(unsigned int i = 0; i < MAX_BLOCKS; i++)
{
// We check to see if blocks are active
if(g_bBlock[i].isActive)
{
// If there is a collision with one of these blocks
if(ball.x <= g_bBlock[i].width
|| ball.width >= g_bBlock[i].x
|| ball.y <= g_bBlock[i].height
|| ball.height <= g_bBlock[i].y)
{
// Then switch the block to inactive
g_bBlock[i].isActive = false;
// I assume yStep is the speed the ball is going?
// If so it is reversed and the ball move backwards.
yStep *= -1;
}
}
}

I have commented each step to assist in understanding. See if you understand this and get back to us, tell us what is going on. Try not to code with so many magic numbers, it makes it nearly impossible to understand later, when attempting to convert to use variables.

Regards,

Stitchs.

##### Share on other sites
actually the code I am using works just fine all I need to do is get the scoring to work

## Create an account

Register a new account

• ### Forum Statistics

• Total Topics
628357
• Total Posts
2982227

• 10
• 9
• 10
• 24
• 11