I want to develop a little vector based graphics editor with Delphi / Andorra 2D
I looked around in all available docs and sources, but I couldn't find out how to scale the display (zoom) and how
to move around in the drawing (if it is larger than the display size)
Here is what I tried to do:
2) matView := AdMatrix_Translate(-170,-170,0);
3) //matView := AdMatrix_Scale(0.5,0.5,1);
I can translate OR I can scale, but how can I do both?
Am I on the right way or is there another way to manage this things?
P.S: If I (later) want to paint on the zommed and translated drawing via mouse actions,
will I also have to recalculate the mouse coordinates?
You can combine the two linear mappings by calculating the matrix product. In order to transform the mouse coordinates, use the inverse matrix - its just a bit of mathematics ;-)
Thanks a lot for your fast reply.
Matrix product … hmmm … time at school lies long ahead, but I think with pen and paper I could manage that.
But to be honest: I'm a bloody novice with Andorra2D, I only know that this a wonderful product, as far as I can judge it.
Years ago I tried to do some of the things that Andorra can do by scratch, this is why I have pretty gray hairs now.
It really would be great if you could drop me a few lines how to multiplicate and inverse those matrices in Andorra2D …
Thanks for your help. :-)
You can multiply matrices using the AdMatrix_Multiply function.
Andorra 2D has no function to invert matrices, but in your case this can also be done by scaling by 1/s and translating by -x and -y.
At all, I think it is very hard to write a vector-graphics application without some knowledge about linear algebra, and Andorra 2D won't be doing the math for you.
Sure, I am aware that linear algebra is necessary to do the desired things.
But there are a lot of other questions, maybe you can give me a few hints or a tip for a good tutorial,
if and how I can do the things I like to do.
In another of your postings I read, that it's possible to move a camera over a 2D-Scene. Maybe I could do zooming/panning
Maybe I describe a little better what my problems are:
I want to create a component (inherited from TPanel), lets call it cfAndorraPanel.
This panel sould display a grid, and handle mouse-events (mouse down, mouse up, mousewheel etc)
By clicking on the canvas and dragging I should be able to draw lines, polygones etc.
and store it in an internal list with extra properties (color, line style etc.) besides the coordinates.
(This already works partially, I also have created a rudimentary algorithm to select a line via mouse-pos and click )
Now I want to zoom in (at mousepos) or click in the canvas and drag the whole scene to a new position)
( Dragging also works, but unfortunatelly my grid is also dragged away :-( )
If I scale with the mouse-wheel the whole scene is scaled (thanks your hint to use mat-multiplication)
but also moved in x- and y- direction (because scene shrinks or expands)
but I want it "scale around the mouse-pointer" (sorry, I'm German and can't explain it better in Englisch)
It would be really great if you could tell me if I am on the right way or if this things can be done better with
Andorra functionality …
P.S: I tried with moving a camera in x, y and z direction (camera up and down to zoom), but my result was not orthogonal,
when I moved up, down, right or left with the camera the figures had a perspectively distortion.
If all my zoom/pan-problems can done by moving around the camera, is there a way to switch to orthogonal mode?
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