* rotate: perform arbitrary rotations
@ 2020-02-16 18:43 rgl
2020-02-16 19:34 ` [9front] " Eli Cohen
` (3 more replies)
0 siblings, 4 replies; 7+ messages in thread
From: rgl @ 2020-02-16 18:43 UTC (permalink / raw)
To: 9front
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hi all,
would it be OK to commit this?
-rodri
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diff -r 287d82efe5f2 sys/src/cmd/rotate.c
--- a/sys/src/cmd/rotate.c Mon Jan 13 23:22:35 2020 +0000
+++ b/sys/src/cmd/rotate.c Sun Feb 16 19:37:26 2020 +0100
@@ -3,6 +3,49 @@
#include <draw.h>
#include <memdraw.h>
+double
+round(double n)
+{
+ return floor(n + 0.5);
+}
+
+Point
+rotatept(Point p, double θ, Point c)
+{
+ Point r;
+
+ p = subpt(p, c);
+ r.x = round(p.x*cos(θ) - p.y*sin(θ));
+ r.y = round(p.x*sin(θ) + p.y*cos(θ));
+ r = addpt(r, c);
+ return r;
+}
+
+Memimage*
+rotate(Memimage *m, double θ)
+{
+ Memimage *w;
+ Rectangle r;
+ Point p, c;
+
+ if((w = allocmemimage(m->r, m->chan)) == nil)
+ sysfatal("allocmemimage: %r");
+ memfillcolor(w, DTransparent);
+ c = divpt(addpt(m->r.min, m->r.max), 2);
+ for(r = m->r; r.min.y < m->r.max.y; r.min.y++){
+ r.min.x = m->r.min.x;
+ r.max.y = r.min.y+1;
+ for(; r.min.x < m->r.max.x; r.min.x++){
+ r.max.x = r.min.x+1;
+ p = rotatept(r.min, θ, c);
+ if(ptinrect(p, m->r))
+ memimagedraw(w, r, m, p, nil, ZP, S);
+ }
+ }
+ freememimage(m);
+ return w;
+}
+
Memimage*
rot90(Memimage *m)
{
@@ -92,10 +135,11 @@
main(int argc, char *argv[])
{
Memimage *m;
- int fd, r;
+ int fd, r, wasright;
char f;
f = 0;
+ wasright = 0;
r = 0;
fd = 0;
ARGBEGIN {
@@ -131,8 +175,11 @@
m = rot90(m);
case 90:
m = rot90(m);
+ wasright++;
break;
}
+ if(!wasright)
+ m = rotate(m, -r*PI/180);
if(writememimage(1, m) < 0)
sysfatal("writememimage: %r");
exits(0);
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [9front] rotate: perform arbitrary rotations
2020-02-16 18:43 rotate: perform arbitrary rotations rgl
@ 2020-02-16 19:34 ` Eli Cohen
2020-02-16 20:01 ` rgl
2020-02-16 19:59 ` Steve Simon
` (2 subsequent siblings)
3 siblings, 1 reply; 7+ messages in thread
From: Eli Cohen @ 2020-02-16 19:34 UTC (permalink / raw)
To: 9front
nice! all in favor say meow
On Sun, Feb 16, 2020 at 10:44 AM <rgl@antares-labs.eu> wrote:
>
> hi all,
>
> would it be OK to commit this?
>
>
> -rodri
> diff -r 287d82efe5f2 sys/src/cmd/rotate.c
> --- a/sys/src/cmd/rotate.c Mon Jan 13 23:22:35 2020 +0000
> +++ b/sys/src/cmd/rotate.c Sun Feb 16 19:37:26 2020 +0100
> @@ -3,6 +3,49 @@
> #include <draw.h>
> #include <memdraw.h>
>
> +double
> +round(double n)
> +{
> + return floor(n + 0.5);
> +}
> +
> +Point
> +rotatept(Point p, double θ, Point c)
> +{
> + Point r;
> +
> + p = subpt(p, c);
> + r.x = round(p.x*cos(θ) - p.y*sin(θ));
> + r.y = round(p.x*sin(θ) + p.y*cos(θ));
> + r = addpt(r, c);
> + return r;
> +}
> +
> +Memimage*
> +rotate(Memimage *m, double θ)
> +{
> + Memimage *w;
> + Rectangle r;
> + Point p, c;
> +
> + if((w = allocmemimage(m->r, m->chan)) == nil)
> + sysfatal("allocmemimage: %r");
> + memfillcolor(w, DTransparent);
> + c = divpt(addpt(m->r.min, m->r.max), 2);
> + for(r = m->r; r.min.y < m->r.max.y; r.min.y++){
> + r.min.x = m->r.min.x;
> + r.max.y = r.min.y+1;
> + for(; r.min.x < m->r.max.x; r.min.x++){
> + r.max.x = r.min.x+1;
> + p = rotatept(r.min, θ, c);
> + if(ptinrect(p, m->r))
> + memimagedraw(w, r, m, p, nil, ZP, S);
> + }
> + }
> + freememimage(m);
> + return w;
> +}
> +
> Memimage*
> rot90(Memimage *m)
> {
> @@ -92,10 +135,11 @@
> main(int argc, char *argv[])
> {
> Memimage *m;
> - int fd, r;
> + int fd, r, wasright;
> char f;
>
> f = 0;
> + wasright = 0;
> r = 0;
> fd = 0;
> ARGBEGIN {
> @@ -131,8 +175,11 @@
> m = rot90(m);
> case 90:
> m = rot90(m);
> + wasright++;
> break;
> }
> + if(!wasright)
> + m = rotate(m, -r*PI/180);
> if(writememimage(1, m) < 0)
> sysfatal("writememimage: %r");
> exits(0);
--
http://echoline.org
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [9front] rotate: perform arbitrary rotations
2020-02-16 19:34 ` [9front] " Eli Cohen
@ 2020-02-16 20:01 ` rgl
0 siblings, 0 replies; 7+ messages in thread
From: rgl @ 2020-02-16 20:01 UTC (permalink / raw)
To: 9front
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this one is better.
i'll try to come up with a crop-free method.
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diff -r 287d82efe5f2 sys/src/cmd/rotate.c
--- a/sys/src/cmd/rotate.c Mon Jan 13 23:22:35 2020 +0000
+++ b/sys/src/cmd/rotate.c Sun Feb 16 20:55:33 2020 +0100
@@ -3,6 +3,49 @@
#include <draw.h>
#include <memdraw.h>
+double
+round(double n)
+{
+ return floor(n + 0.5);
+}
+
+Point
+rotatept(Point p, double θ, Point c)
+{
+ Point r;
+
+ p = subpt(p, c);
+ r.x = round(p.x*cos(θ) - p.y*sin(θ));
+ r.y = round(p.x*sin(θ) + p.y*cos(θ));
+ r = addpt(r, c);
+ return r;
+}
+
+Memimage*
+rotate(Memimage *m, double θ)
+{
+ Memimage *w;
+ Rectangle r;
+ Point p, c;
+
+ if((w = allocmemimage(m->r, m->chan)) == nil)
+ sysfatal("allocmemimage: %r");
+ memfillcolor(w, DTransparent);
+ c = divpt(addpt(m->r.min, m->r.max), 2);
+ for(r = m->r; r.min.y < m->r.max.y; r.min.y++){
+ r.min.x = m->r.min.x;
+ r.max.y = r.min.y+1;
+ for(; r.min.x < m->r.max.x; r.min.x++){
+ r.max.x = r.min.x+1;
+ p = rotatept(r.min, θ, c);
+ if(ptinrect(p, m->r))
+ memimagedraw(w, r, m, p, nil, ZP, S);
+ }
+ }
+ freememimage(m);
+ return w;
+}
+
Memimage*
rot90(Memimage *m)
{
@@ -124,15 +167,10 @@
if(f == 'l')
r = 180;
}
- switch(r % 360){
- case 270:
+ for(r %= 360; r >= 90; r -= 90)
m = rot90(m);
- case 180:
- m = rot90(m);
- case 90:
- m = rot90(m);
- break;
- }
+ if(r > 0)
+ m = rotate(m, -r*PI/180);
if(writememimage(1, m) < 0)
sysfatal("writememimage: %r");
exits(0);
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [9front] rotate: perform arbitrary rotations
2020-02-16 18:43 rotate: perform arbitrary rotations rgl
2020-02-16 19:34 ` [9front] " Eli Cohen
@ 2020-02-16 19:59 ` Steve Simon
2020-02-16 20:05 ` rgl
2020-02-17 23:33 ` cinap_lenrek
2020-02-18 14:43 ` ori
3 siblings, 1 reply; 7+ messages in thread
From: Steve Simon @ 2020-02-16 19:59 UTC (permalink / raw)
To: 9front
rotating every point is correct but slow,
perhaps it would be worth putting the effort in to implement the triple shear algorithm?
-Steve
> On 16 Feb 2020, at 6:44 pm, rgl@antares-labs.eu wrote:
>
> ARGBEGIN {
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [9front] rotate: perform arbitrary rotations
2020-02-16 18:43 rotate: perform arbitrary rotations rgl
2020-02-16 19:34 ` [9front] " Eli Cohen
2020-02-16 19:59 ` Steve Simon
@ 2020-02-17 23:33 ` cinap_lenrek
2020-02-18 14:43 ` ori
3 siblings, 0 replies; 7+ messages in thread
From: cinap_lenrek @ 2020-02-17 23:33 UTC (permalink / raw)
To: 9front
IST EIN *NEIN* STACKENBLOCHEN!!!
--
cinap
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [9front] rotate: perform arbitrary rotations
2020-02-16 18:43 rotate: perform arbitrary rotations rgl
` (2 preceding siblings ...)
2020-02-17 23:33 ` cinap_lenrek
@ 2020-02-18 14:43 ` ori
3 siblings, 0 replies; 7+ messages in thread
From: ori @ 2020-02-18 14:43 UTC (permalink / raw)
To: rgl, 9front
> hi all,
>
> would it be OK to commit this?
>
>
> -rodri
>
> +Memimage*
> +rotate(Memimage *m, double θ)
> +{
> + Memimage *w;
> + Rectangle r;
> + Point p, c;
> +
> + if((w = allocmemimage(m->r, m->chan)) == nil)
> + sysfatal("allocmemimage: %r");
> + memfillcolor(w, DTransparent);
> + c = divpt(addpt(m->r.min, m->r.max), 2);
> + for(r = m->r; r.min.y < m->r.max.y; r.min.y++){
> + r.min.x = m->r.min.x;
> + r.max.y = r.min.y+1;
> + for(; r.min.x < m->r.max.x; r.min.x++){
> + r.max.x = r.min.x+1;
> + p = rotatept(r.min, θ, c);
> + if(ptinrect(p, m->r))
> + memimagedraw(w, r, m, p, nil, ZP, S);
> + }
> + }
> + freememimage(m);
> + return w;
> +}
This is probably not going to give very good results,
since you're not doing any filtering.
There are good algorithms for doing affine transformations.
It's probably worth doing that.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-02-18 14:43 UTC | newest]
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-- links below jump to the message on this page --
2020-02-16 18:43 rotate: perform arbitrary rotations rgl
2020-02-16 19:34 ` [9front] " Eli Cohen
2020-02-16 20:01 ` rgl
2020-02-16 19:59 ` Steve Simon
2020-02-16 20:05 ` rgl
2020-02-17 23:33 ` cinap_lenrek
2020-02-18 14:43 ` ori
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