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ncvisual_rotate: perfect rotate_bounding_box() #599

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pull/602/head
nick black 4 years ago
parent 18ba212709
commit 7aa488f419
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GPG Key ID: 5F43400C21CBFACC
3 changed files with 85 additions and 15 deletions
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3
src/lib/internal.h
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@ -643,6 +643,9 @@ ncplane* rotate_plane(const ncplane* n);
void* bgra_to_rgba(const void* data, int rows, int rowstride, int cols);
// find the "center" cell of two lengths. in the case of even rows/columns, we
// place the center on the top/left. in such a case there will be one more
// cell to the bottom/right of the center.
static inline void
center_box(int* RESTRICT y, int* RESTRICT x){
if(y){

94
src/lib/visual.cpp
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@ -252,6 +252,73 @@ auto ncvisual_bounding_box(const ncvisual* ncv, int* leny, int* lenx,
return *leny * *lenx;
}
// rotate the 0-indexed (origin-indexed) ['y', 'x'] through 'ctheta' and
// 'stheta' around the centerpoint at ['centy', 'centx']. write the results
// back to 'y' and 'x'.
static auto
rotate_point(int* y, int* x, double stheta, double ctheta, int centy, int centx) -> void {
// convert coordinates from origin to left-handed cartesian
const int convx = *x - centx;
const int convy = *y - centy;
//fprintf(stderr, "%d, %d -> conv %d, %d\n", *y, *x, convy, convx);
*x = round(convx * ctheta - convy * stheta);
*y = round(convx * stheta + convy * ctheta);
}
// rotate the specified bounding box by the specified sine and cosine of some
// theta radians, enlarging or shrinking it as necessary. returns the area.
// 'leny', 'lenx', 'offy', and 'offx' describe the bounding box to be rotated,
// and might all be updated (in either direction).
static auto
rotate_bounding_box(double stheta, double ctheta, int* leny, int* lenx,
int* offy, int* offx) -> int {
//fprintf(stderr, "Incoming bounding box: %dx%d @ %dx%d rotate s(%f) c(%f)\n", *leny, *lenx, *offy, *offx, stheta, ctheta);
int xs[4], ys[4]; // x and y locations of rotated coordinates
int centy = *leny;
int centx = *lenx;
center_box(&centy, &centx);
ys[0] = 0;
xs[0] = 0;
rotate_point(ys, xs, stheta, ctheta, centy, centx);
//fprintf(stderr, "rotated %d, %d -> %d %d\n", 0, 0, ys[0], xs[0]);
ys[1] = 0;
xs[1] = *lenx - 1;
rotate_point(ys + 1, xs + 1, stheta, ctheta, centy, centx);
//fprintf(stderr, "rotated %d, %d -> %d %d\n", 0, *lenx - 1, ys[1], xs[1]);
ys[2] = *leny - 1;
xs[2] = *lenx - 1;
rotate_point(ys + 2, xs + 2, stheta, ctheta, centy, centx);
//fprintf(stderr, "rotated %d, %d -> %d %d\n", *leny - 1, *lenx - 1, ys[2], xs[2]);
ys[3] = *leny - 1;
xs[3] = 0;
rotate_point(ys + 3, xs + 3, stheta, ctheta, centy, centx);
//fprintf(stderr, "rotated %d, %d -> %d %d\n", *leny - 1, 0, ys[3], xs[3]);
int trow = ys[0];
int brow = ys[0];
int lcol = xs[0];
int rcol = xs[0];
for(size_t i = 1 ; i < sizeof(xs) / sizeof(*xs) ; ++i){
if(xs[i] < lcol){
lcol = xs[i];
}
if(xs[i] > rcol){
rcol = xs[i];
}
if(ys[i] < trow){
trow = ys[i];
}
if(ys[i] > brow){
brow = ys[i];
}
}
*offy = trow;
*leny = brow - trow + 1;
*offx = lcol;
*lenx = rcol - lcol + 1;
//fprintf(stderr, "Rotated bounding box: %dx%d @ %dx%d\n", *leny, *lenx, *offy, *offx);
return *leny * *lenx;
}
// find the "center" cell of a visual. in the case of even rows/columns, we
// place the center on the top/left. in such a case there will be one more
// cell to the bottom/right of the center.
@ -267,11 +334,11 @@ auto ncvisual_rotate(ncvisual* ncv, double rads) -> int {
if(ncv->data == nullptr){
return -1;
}
int centy, centx;
ncvisual_center(ncv, &centy, &centx); // pixel center (center of 'data')
double stheta, ctheta; // sine, cosine
stheta = sin(rads);
ctheta = cos(rads);
int centy, centx;
ncvisual_center(ncv, &centy, &centx); // pixel center (center of 'data')
// bounding box for real data within the ncvisual. we must only resize to
// accommodate real data, lest we grow without band as we rotate.
// see https://github.com/dankamongmen/notcurses/issues/599.
@ -279,9 +346,13 @@ auto ncvisual_rotate(ncvisual* ncv, double rads) -> int {
int bbx = ncv->dstwidth;
int bboffy = 0;
int bboffx = 0;
if(ncvisual_bounding_box(ncv, &bby, &bbx, &bboffy, &bboffx) <= 0){
return -1;
}
int bbarea;
if((bbarea = ncvisual_bounding_box(ncv, &bby, &bbx, &bboffy, &bboffx)) == 0){
return 0;
bbarea = rotate_bounding_box(stheta, ctheta, &bby, &bbx, &bboffy, &bboffx);
if(bbarea <= 0){
return -1;
}
int bbcentx = bbx, bbcenty = bby;
center_box(&bbcenty, &bbcentx);
@ -296,19 +367,16 @@ auto ncvisual_rotate(ncvisual* ncv, double rads) -> int {
return -1;
}
memset(data, 0, bbarea * 4);
//fprintf(stderr, "prad: %d DIAM: %d CENTER: %d/%d LEN: %d/%d\n", prad, diam, centy, centx, ncv->ncp->leny, ncv->ncp->lenx);
//fprintf(stderr, "bbarea: %d bby: %d bbx: %d centy: %d centx: %d\n", bbarea, bby, bbx, centy, centx);
for(int y = 0 ; y < ncv->dstheight ; ++y){
for(int x = 0 ; x < ncv->dstwidth ; ++x){
const int convx = x - centx;
const int convy = y - centy; // converted coordinates
const int targx = convx * ctheta - convy * stheta;
const int targy = convx * stheta + convy * ctheta;
const int deconvx = targx + bbcentx;
const int deconvy = targy + bbcenty;
int targx = x, targy = y;
rotate_point(&targy, &targx, stheta, ctheta, centy, centx);
const int deconvx = targx - bboffx/*bbcentx*/;
const int deconvy = targy - bboffy/*bbcenty*/;
if(deconvy < 0 || deconvx < 0 || deconvy >= bby || deconvx >= bbx){
//fprintf(stderr, "NOCOPY %d/%d -> %d/%d -> %d/%d -> %d/%d (%dx%d + %dx%d)\n", y, x, convy, convx, targy, targx, deconvy, deconvx, bboffy, bboffx, bby, bbx);
fprintf(stderr, "NOCOPY %d/%d -> %d/%d -> %d/%d (%dx%d + %dx%d)\n", y, x, targy, targx, deconvy, deconvx, bboffy, bboffx, bby, bbx);
}else{
//fprintf(stderr, "YESCOPY %d/%d (%d) <- (%d) %08x\n", deconvy, deconvx, deconvy * ncv->dstwidth + deconvx, y * (ncv->rowstride / 4) + x, ncv->data[y * (ncv->rowstride / 4) + x]);
data[deconvy * bbx + deconvx] = ncv->data[y * (ncv->rowstride / 4) + x];
}
// data[deconvy * (ncv->dstwidth) + deconvx] = ncv->data[y * (ncv->rowstride / 4) + x];

3
src/poc/visual.cpp
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@ -44,7 +44,7 @@ int main(int argc, char** argv){
goto err;
}
for(double i = 0 ; i < 256 ; ++i){
if(ncvisual_rotate(ncv, M_PI / 8)){
if(ncvisual_rotate(ncv, M_PI / 2)){
failed = true;
break;
}
@ -56,7 +56,6 @@ int main(int argc, char** argv){
failed = true;
break;
}
sleep(1);
}
return notcurses_stop(nc) || failed ? EXIT_FAILURE : EXIT_SUCCESS;

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