HP Forums

Hello!

I'm trying to make a drawing in the Prime, but I realize I can't rotate texts!
I just wanted to rotate the "distance=?" text a couple of degrees, so it aligns with the green line (screen shot).

Here's my code:

EXPORT AboutESP()
BEGIN
RECT();
DIMGROB_P(G1,320,240);
RECT_P(G1,RGB(255,255,255));
LINE_P(G1,0,197,320,50,RGB(0,0,0));
LINE_P(G1,52,153,265,55,RGB(40,220,170));
LINE_P(G1,57,165,44,137,RGB(0,0,0));
LINE_P(G1,270,68,260,41,RGB(0,0,0));
RECT_P(G1,0,0,320,26,RGB(0,160,128));
TEXTOUT_P("Finding the distance between 2 points.",G1,25,2,4,RGB(255,255,255));

TEXTOUT_P("(x1,y1)",G1,55,175,2,RGB(0,0,0));
TEXTOUT_P("(x2,y2)",G1,270,79,2,RGB(0,0,0));
TEXTOUT_P("●",G1,56,162,3,RGB(255,0,0));
TEXTOUT_P("●",G1,268,65,3,RGB(255,0,0));
TEXTOUT_P("distance=?",G1,100,85,5,RGB(255,0,0));//this one I need to rotate.

TRIANGLE_P(G1,255,57,257,61,266,54,RGB(0,0,0));
TRIANGLE_P(G1,62,151,51,154,60,146,RGB(0,0,0));
BLIT_P(G0,G1);
FREEZE;
END;

I'll appreciate any help, Thank you.

To rotate something, simplest way is to use a translation matrix (i.e. with xyz vectors). Of course you can use a simpler form if you don't consider the axis of the rotation (make it 0) and remove z:

Code:

local mat:=[[cos(angle),sin(angle)],[-sin(angle),cos(angle)]];

The new position of every rotated pixel will be equal to:

Code:

newpos:=mat*[[sourceX],[sourceY]];

Working code:

Code:

RotateG(source,destination,angle)

BEGIN

DIMGROB(destination,320,240);

// Rotate matrix

local tmp;local mat:=[[cos(angle),sin(angle)],[-sin(angle),cos(angle)]];

FOR X FROM 0 TO grobh(source) DO

FOR Y FROM 0 TO grobw(source) DO

tmp:=mat*[[X],[Y]];

PIXON_P(destination,X,Y,GETPIX_P(source,tmp(1,1),tmp(2,1)));

end;

end;

END;

EXPORT AboutESP()

BEGIN

RECT();

DIMGROB_P(G1,320,240);

RECT_P(G1,RGB(255,255,255));

LINE_P(G1,0,197,320,50,RGB(0,0,0));

LINE_P(G1,52,153,265,55,RGB(40,220,170));

LINE_P(G1,57,165,44,137,RGB(0,0,0));

LINE_P(G1,270,68,260,41,RGB(0,0,0));

RECT_P(G1,0,0,320,26,RGB(0,160,128));

TEXTOUT_P("Finding the distance between 2 points.",G1,25,2,4,RGB(255,255,255));

TEXTOUT_P("(Straight Line Kit)",G1,95,30,4,RGB(255,255,255));

TEXTOUT_P("(x1,y1)",G1,55,175,2,RGB(0,0,0));

TEXTOUT_P("(x2,y2)",G1,270,79,2,RGB(0,0,0));

TEXTOUT_P("●",G1,56,162,3,RGB(255,0,0));

TEXTOUT_P("●",G1,268,65,3,RGB(255,0,0));

// -----------------------------

DIMGROB(G3,320,240); // temporal

TEXTOUT_P("distance=?",G3,60,130,5,RGB(255,0,0));//this one I need to rotate.

RotateG(G3,G2,-0.4); // Rotate 0.4 radians

BLIT_P(G1,G2,RGB(255,255,255)); // Transparency

// -----------------------------

TRIANGLE_P(G1,255,57,257,61,266,54,RGB(0,0,0));

TRIANGLE_P(G1,62,151,51,154,60,146,RGB(0,0,0));

BLIT_P(G0,G1);

FREEZE;

END;

Of course this code is not very efficient, you may crop the source to size, add the "axis" for the rotation, etc...

Thank you for answering eried!
I wasn't aware of what you showed here, I just thought rotating things was a simpler thing to do, I see this is a little bit more advanced than I thought, but I will review this code until I get a deeper understanding of it.

I think Eried's approach is the best you will get - generate the pixels with the available TEXTOUT_P command then rotate the pixel field on screen.

A wackier option would be to build text characters out of LINE_P statements - making a sort of vector font. Tedious, but you can get there in the end.

Attached, as an example, is a circular, on-screen slide rule I coded in Borland Delphi many years ago using this approach.

I defined blocky but serviceable numeric characters using Delphi line drawing statements. I seem to remember that rotating these vector elements to animate the rule and its scales then wasn't too difficult.

NB, I think the slide rule runs fine on newer versions of Windows but the window might be sizeable, even though it was defined to be of fixed size in Delphi. This spoils the show a bit. Anyway, It runs as designed on my Linux/Wine set-up.

Spybot

eried

Spybot

Chasfield