rotate an 8byte array

[adam johnson]

Hi guys/Gals.
I want to rotate an 8 byte array, to create a spinning effect, i.e.

char_buff[0] = 0x81;
char_buff[1] = 0x42;
char_buff[2] = 0x24;
char_buff[3] = 0x18;
char_buff[4] = 0x18;
char_buff[5] = 0x24;
char_buff[6] = 0x42;
char_buff[7] = 0x81;

this makes up a "character" , any ideas as how I can rotate it. not just 90 degrees, 180, 270. that bits easy. but a full 'spin'?

Thanks guys.

[weaknessforcats]

What, exactly, is a full spin?

[adam johnson]

i would like to rotate this 8x8 character array around its center point. so it look like the character is turning round.

[weaknessforcats]

You will need a graphic O/S for that.

You don't say what you are using but a console C app can't do what you want.

[lspxy]

char swap = '\0';
for (i = 0; (i < 8, j = 7 - i) && (i <= j); i++)
{
    swap = char_buff[i];
    char_buff[i] = char_buff[j];
    char_buff[j] = swap;
}

[adam johnson]

thankyou. I can already do the easy rotates as i said earlier. I was thinking more along te lines of of a 0-360 degree rotate. Tried a few ways and although i do get a rotation "of sorts" its not good.
I was thinking along the lines of plotting an 8x8 square at a given angle and then filling the area in with my 8x8 array. I think i must be getting some weird rounding problems ans stuff. Just about given up now. Heres what ive got so far:-

rotate_array ( 30,30, 'A', angle );

void rotate_array( int xpos, int ypos, int character, int angle )
{
double newX, newY;
double radians = (double)angle; // radians = angle * (PI/180);
double pX=3, pY=3; // centre of character
int x, y, index=character *8; // index character in my array
int char_width = 7; // character height in bits
int char_height = 7; // character width in bits
int row, mask;

// characters are held in 8x8 array. However, the character data
// is really only 7x6, thats removing spacing for printing etc.
// so we will ignore row 7, column 0

for (y=0; y<char_height; y++)
{
row = char_buff[ index+y ]; /* first byte of character */

for (x=char_width; x>=1; x--)
{
// rotate a point (x,y) angle around (pX, pY)
// NOTE: we are using the angle NOT radians.

newX = 0.5 + ((x-pX)*cos(radians ) - (y-pY)*sin(radians ) + pX);
newY = 0.5 + ((x-pX)*sin(radians ) + (y-pY)*cos(radians ) + pY);

SET_CURSOR( xpos+newX, ypos+newY );
mask = 1 << x;
if (row & mask) printf("%c", 219 );
else printf(".");
}
}
}

[adam johnson]

the problem seem to be plotting the square. Holes are left by the newX,newY points.And some points are used twice. Anyideas anyone? I do use radian instead of angle now too.

newX = ((x-pX)*cos(radians ) - (y-pY)*sin(radians )) + pX;
newY = ((x-pX)*sin(radians ) + (y-pY)*cos(radians )) + pY;