Draw a TTF font on it's side?

nshade

Member #4,372

February 2004

I'm not seeing a function for this, but is there a easy way to draw text sideways, (rotated 90 degrees) is there a trick to doing it?

Elias

Member #358

May 2000

Something like this should work:

al_identity_transform(&t);
al_rotate_transform(&t, pi / 2);
al_use_transform(&t);
al_draw_text(...);

--
"Either help out or stop whining" - Evert

Edgar Reynaldo

Major Reynaldo

May 2007

Do you mean draw the text vertically or actually turn it on its side?

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King Piccolo will make it so Then I could just flip it with some sweet, sweet matrix math. In either case, I’ll ride this wagon until the wheels fall off. Thanks to those that keep it running

nshade

Member #4,372

February 2004

Turn it on it's side. I would use the example above, but what on earth is t pointing at?

Edgar Reynaldo

Major Reynaldo

May 2007

EDIT
Oh I get you. t is an ALLEGRO_TRANSFORM*.

T doesn't point at anything, it's a transform, not a vector. He sets up the transform to rotate around the origin by 90 degrees clockwise and then uses the transform before drawing the text. You'll probably want to center your text before you rotate it though.

ALLEGRO_TRANSFORM t;
al_identity_transform(&t);
al_translate_transform(&t , -xpos , -ypos);
al_rotate_transform(&t , M_PI/2.0f);
al_translate_transform(&t , xpos , ypos);
al_use_transform(&t);
al_draw_text(font , al_map_rgb(255,255,255) , xpos , ypos , ALLEGRO_ALIGN_CENTER , my_string);

nshade

Member #4,372

February 2004

I'm not at my main system right now, but does that transform the whole drawing surface. As in, if I was to paste bitmaps or draw primitives, they will also be transformed as well until I reset the use_transform();

Edgar Reynaldo

Major Reynaldo

May 2007

The transforms that you 'use' affect the current bitmap target only. But if that is the backbuffer, then it affects all drawing.

nshade

Member #4,372

February 2004

I guess the question is, how do you set it back to normal after the text print. There doesn't seem to be a "clear" command and I have other non-rotated things being drawn to my target bitmap. (I admit my matrix math is a little weak so I don't know what an "identity" is)

Edgar Reynaldo

Major Reynaldo

May 2007

I think its in the manual.

http://liballeg.org/a5docs/trunk/transformations.html#al_use_transform

Quote:

Call this function with an identity transformation to return to the default behaviour.

However, to reset the projection transform is a little different. But you didn't alter that, so no worries.

jmasterx

Member #11,410

October 2009

  int GraphicsContext::drawRotatedText( const std::string& text,agui::Font* font,const agui::Color& color, int x, int y, float deg, int flags )
  {
    int fx = font->getTextWidth(text) / 2;
    int fy = font->getLineHeight() / 2;
    m_transform.identity();
    m_transform.translate(-fx,-fy);
    m_transform.rotate(deg);
    m_transform.translate(x,y);
    useTransform(m_transform);
    drawText(text,font,color,0,0,flags);
    resetTransform();
    return fx * 2;
  }

https://github.com/jmasterx/StemwaterSpades/blob/master/Spades%20Game/Game/Engine/GraphicsContext.cpp

Agui GUI API -> https://github.com/jmasterx/Agui
Agui 0.2 Release Thread -> https://www.allegro.cc/forums/thread/612830