Locking up!

Ok, so I did a tutorial on basic animation and then I made a sprite map and altered the program to use the numpad to go in all 8 directions (tut was 4). This all worked just peachy, then I decided to try and alter it again to chase the mouse around the screen, which is does but if it goes to the right or bot of the screen it locks up.

Code:

void SPRITE::HandleEvent(SDL_Event* event) { switch(event->type) { case SDL_QUIT: { Running = false; break; } case SDL_MOUSEMOTION: { MousePosition(event); break; } default: break; } } bool SPRITE::MousePosition(SDL_Event* event) { int mX = event->motion.x; int mY = event->motion.y; if(mX != mouseX || mY != mouseY) { mouseX = mX; mouseY = mY; return true; } return false; } void SPRITE::ChaseMouse() { int direction = 0; int moveX, moveY; // is sprite at cursor? while( (x != mouseX) || (y != mouseY)) { moveX = ( mouseX - x ); moveY = ( mouseY - y ); // decide which direction to move towards cursor if(moveX > 0 && moveY > 0) direction = 3; else if(moveX > 0 && moveY < 0) direction = 9; else if(moveX < 0 && moveY > 0) direction = 1; else if(moveX < 0 && moveY < 0) direction = 7; else if(moveX > 0) direction = 6; else if(moveX < 0) direction = 4; else if(moveY > 0) direction = 2; else if(moveY < 0) direction = 8; // Set velocity and section of spritemap switch(direction) { case 8: { yVel -= SPRITE_HEIGHT / 63; section.x = 65; section.y = 0; break; } case 2: { yVel += SPRITE_HEIGHT / 63; section.x = 65; section.y = 130; break; } case 4: { xVel -= SPRITE_WIDTH / 63; section.x = 0; section.y = 65; break; } case 6: { xVel += SPRITE_WIDTH / 63; section.x = 130; section.y = 65; break; } case 7: { xVel -= SPRITE_WIDTH / 63; yVel -= SPRITE_HEIGHT / 63; section.x = 0; section.y = 0; break; } case 9: { xVel += SPRITE_WIDTH / 63; yVel -= SPRITE_HEIGHT / 63; section.x = 130; section.y = 0; break; } case 1: { xVel -= SPRITE_WIDTH / 63; yVel += SPRITE_HEIGHT / 63; section.x = 0; section.y = 130; break; } case 3: { xVel += SPRITE_HEIGHT / 63; yVel += SPRITE_HEIGHT / 63; section.x = 130; section.y = 130; break; } default: break; } Move(); switch( direction ) { case 8: yVel += SPRITE_HEIGHT / 63; break; case 2: yVel -= SPRITE_HEIGHT / 63; break; case 4: xVel += SPRITE_WIDTH / 63; break; case 6: xVel -= SPRITE_WIDTH / 63; break; case 7: xVel += SPRITE_WIDTH/63; yVel += SPRITE_HEIGHT/63; break; case 9: xVel -= SPRITE_WIDTH/63; yVel += SPRITE_HEIGHT/63; break; case 1: xVel += SPRITE_WIDTH/63; yVel -= SPRITE_HEIGHT/63; break; case 3: xVel -= SPRITE_WIDTH/63; yVel -= SPRITE_HEIGHT/63; break; default: break; } } section.x = 65; section.y = 65; Move(); } bool SPRITE::Execute(TIMER& GameTimer, SDL_Event* event) { Running = true; if(Initialize() == false) { return -1; } while(Running) { GameTimer.Start(); SDL_PollEvent(event); { HandleEvent(event); } ChaseMouse(); if( GameTimer.Get_Ticks() < 1000 / FRAMES_PER_SECOND ) { SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - GameTimer.Get_Ticks() ); } GameTimer.Stop(); } SDL_Quit(); return 0; } void SPRITE::Move() { //Move the sprite left or right x += xVel; //If the sprite went too far to the left or right if( ( x < 0 ) || ( x + SPRITE_WIDTH > SCREEN_WIDTH ) ) { //move back x -= xVel; } //Move the sprite up or down y += yVel; //If the sprite went too far up or down if( ( y < 0 ) || ( y + SPRITE_HEIGHT > SCREEN_HEIGHT ) ) { //move back y -= yVel; } //Fill the screen white SDL_FillRect( screen, &screen->clip_rect, SDL_MapRGB( screen->format, 0xFF, 0xFF, 0xFF ) ); //Show the sprite on the screen Show(); //Update the screen SDL_Flip( screen ); } void SPRITE::Show() { //Show the sprite ApplySurface( sprite, section, screen, x, y ); }

This is all the relevant code. I tried changing the right and bot boundries in Move(), but it just locked up farther away from the edge. Being ignorant while learning is such a pain.

Any feedback on the ChaseMouse() and MousePosition() funcs would be cool as well, as these are mostly mine. Please feel free to straighten me out on what I did wrong and how. EDIT:: My commenting is really poor, this is something I need to work on, thanks for your patience.

Code:

//If the sprite went too far to the left or right if( ( x < 0 ) || ( x + SPRITE_WIDTH > SCREEN_WIDTH ) ) { //move back x -= xVel; }

What happens when x is between SCREEN_WIDTH and SCREEN_WIDTH - SPRITE_WIDTH ?
It gets moved back to its previous position and the condition here:

Code:

while( (x != mouseX) || (y != mouseY)) {

will never fail.

Try something like this (assuming x can never be less than 0 or greater than SCREEN_WIDTH-1

Code:

if( x < 0 ) { x=0; } if ( x + SPRITE_WIDTH > SCREEN_WIDTH ) { x = SCREEN_WIDTH - SPRITE_WIDTH; }

And something similar for y.

Is SDL sensitive to sprites moving outside the frustum or the screen?

Code:

if ( x + SPRITE_WIDTH > SCREEN_WIDTH ) { x = SCREEN_WIDTH - SPRITE_WIDTH; }

I changed to your suggestion, but it still ends up with the same result, seizes on the right and bot still.

AND just screwing around I changed to

Code:

if( x + (SPRITE_WIDTH - 63) > SCREEN_WIDTH )

This results in the sprite moving completely off the screen if you move the cursor beyond the window. But, it does not lock up and will come back on-screen if you cursor back over the window again... (My sprite width/height is 63)

Quote:

Is SDL sensitive to sprites moving outside the frustum or the screen?

I've run the sprite off the edge of the window without locking it up, so I don't believe so. EDIT::Which I just did above (again).

Then I seriously doubt that is the source of the lockup. It may be something to look at in your code as another potential problem but I do not think that is the source of your current issue.

I do not understand most of what you are doing in your code but I have built many sprite systems and have never had an issue like what you are describing. My guess would be, and it is only a guess, that you are somehow addressing an area that is off of the sprite sheet in memory and thus causing problems. If you do this in pure D3D nothing happens b/c u,v coords will simply wrap around.

Well, I have gotten it to work, but it seems wrong.

My main loop is now:

Code:

while(Running) { GameTimer.Start(); SDL_PollEvent(event); { HandleEvent(event); } if( x != mouseX || y != mouseY ) { ChaseMouse(); Move(); StopChase(); } else // Set sprite to center { section.x = 65; section.y = 65; Move(); } if( GameTimer.Get_Ticks() < 1000 / FRAMES_PER_SECOND ) { SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - GameTimer.Get_Ticks() ); } GameTimer.Stop(); }

I broke up the ChaseMouse() - which now only sets direction and velocity, and added StopChase().

Code:

void SPRITE::StopChase() { switch( direction ) { case 8: yVel += SPRITE_HEIGHT / VELOCITY; break; case 2: yVel -= SPRITE_HEIGHT / VELOCITY; break; case 4: xVel += SPRITE_WIDTH / VELOCITY; break; case 6: xVel -= SPRITE_WIDTH / VELOCITY; break; case 7: xVel += SPRITE_WIDTH/VELOCITY; yVel += SPRITE_HEIGHT/VELOCITY; break; case 9: xVel -= SPRITE_WIDTH/VELOCITY; yVel += SPRITE_HEIGHT/VELOCITY; break; case 1: xVel += SPRITE_WIDTH/VELOCITY; yVel -= SPRITE_HEIGHT/VELOCITY; break; case 3: xVel -= SPRITE_WIDTH/VELOCITY; yVel -= SPRITE_HEIGHT/VELOCITY; break; default: break; } direction = 0; }

I have a couple new issues however. Anything above a sprite velocity of 1 causes the sprite to jitter when it gets to the mouse position as if it can't quite reach the x and y coords.

Also, why do I have to completely stop the sprite's movement after every move? When I don't, it loops in circles or figure eights...

Is there someplace I can link these things for people to look at if they want? I see some people have been scolded for linking in msgs.

Probably because you're moving your sprites in fixed lengths. If something is 1 foot away from you, but you can only take 3-foot steps, how are you going to reach it?

You can upload your files as attachments or use something like pastebin for smaller code segments. If someone was scolded for posting links, it was probably because he was spamming his personal website.