Python Tetris Rotation Check

Question

I'm trying to create a rotation program for Tetris that I am coding in python. The rotation part works correctly but I have the problem of blocks rotating off the screen or into other blocks. What I have tried to create is a function that will make a test rotation to see if the rotation is valid before actually rotating the block.

The functions are called here:

 if rotatecheck(curblock,rowheight,columnwidth):
        rotate(curblock,rowheight,columnwidth)

where curblock is a list with 4 rect objects and 1 color, columnwidth and rowheight are integers defining the size of the playspace and rotatecheck() is defined as

def rotatecheck(curc, ro, col):
    new=[]
    ct=len(blockonscreen)-1
    if ct==0:
        ct=1
    for z in range(len(curc)):
        new.append(curc[z])
    rotate(new, ro, col)
    for i in range(len(new)-1):
        if new[i].left<0 or new[i].left>=WINDOWWIDTH:
            return False
        for b in blockonscreen:
            if b !=curc:
                for x in range(len(block)-1):
                    if new[i] == block[x]:
                        return False
    return True

blockonscreen is a list of lists containing 4 rect objects and a color, and rotate() is defined as

def rotate(curr,ro,col):
     if curr[4]==yellow:
         rotateo(curr,ro,col)
     elif curr[4]==cyan:
         rotatei(curr,ro,col)
     else:
         rotatea(curr,ro,col)

def rotatei(curr,ro,col):
    if curr[2].centerx>curr[0].centerx and curr[3].centerx>curr[0].centerx:
        horiz=True
        curr[0].centerx+=col
        bla=1
    elif curr[2].centerx<curr[0].centerx and curr[3].centerx<curr[0].centerx:
        horiz=True
        curr[0].centerx-=col
        bla=-1
    elif curr[2].centery>curr[0].centery and curr[3].centery>curr[0].centery:
        horiz=False
        curr[0].centery+=ro
        bla=-1
    elif curr[2].centery<curr[0].centery and curr[3].centery<curr[0].centery:
        horiz=False
        curr[0].centery-=ro
        bla=1
    for f in range (1,4):
        if horiz:
            curr[f].left=curr[0].left
            curr[f].top=curr[0].top+(blocks[0][f-1][0]*ro*bla)
        else:
            curr[f].top=curr[0].top
            curr[f].right=curr[0].right+(blocks[0][f-1][0]*col*bla)
def rotateo(curr,ro,col):
    pass
def rotatea(curr,ro,col):
    middlex=curr[0].centerx
    middley=curr[0].centery
    for r in range(1,4):
        if curr[r].centery==middley and curr[r].centerx>middlex:
            curr[r].centery+=ro
            curr[r].centerx-=col
        elif curr[r].centery==middley and curr[r].centerx<middlex:
            curr[r].centery-=ro
            curr[r].centerx+=col
        elif curr[r].centerx==middlex and curr[r].centery>middley:
            curr[r].centery-=ro
            curr[r].centerx-=col            
        elif curr[r].centerx==middlex and curr[r].centery<middley:
            curr[r].centery+=ro
            curr[r].centerx+=col            
        elif curr[r].centerx>middlex and curr[r].centery>middley:
            curr[r].centerx-=(2*col)
        elif curr[r].centery>middley and curr[r].centerx<middlex:
            curr[r].centery-=(2*ro)
        elif curr[r].centerx<middlex and curr[r].centery<middley:
            curr[r].centerx+=(2*col)
        elif curr[r].centerx>middlex and curr[r].centery<middley:
            curr[r].centery+=(2*ro)

In its current state the program acts as if rotatecheck() doesn't exist. I have scoured my code repeatedly but I can't find anything wrong with it.

Answer 1

It looks like your problem here is that rotatecheck actually rotates the objects you are trying to test, causing them to be rotated even if it does return False.

for z in range(len(curc)):
    new.append(curc[z])

centerx and centery are held in the objects in curc, when you do this you fill a new list with references to the same objects, which are then rotated. You will need to create copies of the individual objects within curc; define a copy method which creates a new object with the same values of e.g. centerx.