CODEWITHSUNDEEP
openglopenframeworks
Andrea F
Andrea F

Reputation: 733

Drawing application with OpenGL/Openframeworks

I'm trying to program a brush stroke/drawing application using OpenGL within Openframeworks. For now I'm just trying to create squiggly lines that follow your mouse.

I've started by using ofpolyline but I have just managed to create a straight line that follows my mouse. I would really appreciate some pseudo code or something to point me in the right direction. 

start. set (mouseX,mouseY);
end.set(mouseX,mouseY);

ofPolyline myline;
myline.addVertex(start.x,start.y);
myline.curveTo(end.x,end.y); 
myline.bezierTo(mouseX,mouseY, mouseX,mouseY,mouseX, mouseY);
myline.addVertex(end.x,end.y);
myline.draw();

Upvotes: 0

Views: 771

Answers (1)

Andreas Haferburg
Andreas Haferburg

Reputation: 5520

A Bezier curve with two vertices is always just a straight line segment. You need to add more vertices/control points to get non-degenerate (round) curves. So you could store the last mouse position somewhere, and add a new vertex when the mouse was moved by a certain amount (eg 20 pixels). Or add a vertex when the user clicks. However, if you always just call bezierTo(x,y,x,y,x,y), you will still only get straight lines. You need to offset the two control points from (x,y) to get round curves.

Upvotes: 1

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