mirror of
https://github.com/isometimes/rpi4-osdev
synced 2024-11-24 19:20:40 +00:00
53 lines
2 KiB
C
53 lines
2 KiB
C
#include "../include/wgt.h"
|
|
|
|
#define fastcopy memcpy
|
|
|
|
void wskew (short x, short y, block image, short degrees)
|
|
{
|
|
float newx, offs, slope;
|
|
long lnewx, lslope;
|
|
/* long values converted from floats (speed up) */
|
|
short ctr; /* y ctr */
|
|
short hgt, wid, display, shx, of2;
|
|
short onewx;
|
|
|
|
hgt = wgetblockheight (image); /* Find height of block */
|
|
wid = wgetblockwidth (image); /* Find width of block */
|
|
slope = (float)degrees / 45; /* Calculate slope of new image */
|
|
offs = ((float)hgt / 2)*slope; /* Find distance to shift horiz. */
|
|
newx = (float)x + offs; /* Calculate new x position */
|
|
onewx = newx; /* Store it as integer for clipping */
|
|
lnewx = (float)newx * 2000; /* Convert floating pt to long int */
|
|
lslope = (float)slope * 2000; /* Convert floating pt to long int */
|
|
|
|
/* Draw each row of image */
|
|
for (ctr = y; ctr < y + hgt - 1; ctr++)
|
|
{
|
|
if (onewx + wid > bx) display = bx + 1 - onewx;
|
|
/* Clip width */
|
|
else display = wid;
|
|
if (onewx < tx) /* See if image overlaps left clip */
|
|
{
|
|
of2 = tx - onewx; /* Find offset into bitmap */
|
|
shx = tx; /* Set to draw starting here */
|
|
display = display - of2; /* New width to draw */
|
|
}
|
|
else
|
|
{
|
|
shx = onewx; /* X value is fine */
|
|
of2 = 0; /* Use entire bitmap */
|
|
}
|
|
/* If width to display >0, and <= original width, and
|
|
we are within top and bottom Y clipping boundaries:
|
|
Copy row of bitmap to visual screen, using DISPLAY contiguous
|
|
bytes.
|
|
*/
|
|
if ((display > 0) & (display <= wid) & (ctr >= ty) & (ctr <= by))
|
|
fastcopy (&abuf[(ctr)*WGT_SYS.xres + shx], &image[(ctr - y)*wid + 2
|
|
+ of2], display);
|
|
lnewx = lnewx - lslope;
|
|
/* Find X position after shifting next row */
|
|
onewx = lnewx / 2000;
|
|
/* Calculate integer value from long int */
|
|
}
|
|
}
|