Smoothing a hand-drawn curve

You can reduce the number of points using the Ramer–Douglas–Peucker algorithm there is a C# implementation here. I gave this a try using WPFs PolyQuadraticBezierSegment and it showed a small amount of improvement depending on the tolerance. After a bit of searching sources (1,2) seem to indicate that using the curve fitting algorithm from Graphic … Read more

How to draw a vector path progressively? (Raphael.js)

Maybe someone is searching for an answer, like me for two days now: // Draw a path and hide it: var root = paper.path(‘M0 50L30 50Q100 100 50 50’).hide(); var length = root.getTotalLength(); // Setup your animation (in my case jQuery): element.animate({ ‘to’: 1 }, { duration: 500, step: function(pos, fx) { var offset = … Read more

How can I fit a Bézier curve to a set of data?

I have similar problem and I have found “An algorithm for automatically fitting digitized curves” from Graphics Gems (1990) about Bezier curve fitting. Additionally to that I have found source code for that article. Unfortunately it is written in C which I don’t know very well. Also, the algorithm is quite hard to understand (at … Read more

Drawing a Topographical Map

The gradient is a mathematical operator that may help you. If you can turn your interpolation into a differentiable function, the gradient of the height will always point in the direction of steepest ascent. All curves of equal height are perpendicular to the gradient of height evaluated at that point. Your idea about starting from … Read more

What is the difference between cubic bezier and quadratic bezier and their use cases?

As you’ve discovered, both Quadratic curves and Cubic Bezier curves just connect 2 points with a curve. Since the Cubic curve has more control points, it is more flexible in the path it takes between those 2 points. For example, let’s say you want to draw this letter “R”: Start drawing with the “non-curvey” parts … Read more

How to convert a 3D point into 2D perspective projection?

The standard way to represent 2D/3D transformations nowadays is by using homogeneous coordinates. [x,y,w] for 2D, and [x,y,z,w] for 3D. Since you have three axes in 3D as well as translation, that information fits perfectly in a 4×4 transformation matrix. I will use column-major matrix notation in this explanation. All matrices are 4×4 unless noted … Read more

Convert a quadratic bezier to a cubic one

From https://fontforge.org/docs/techref/bezier.html#converting-truetype-to-postscript: Any quadratic spline can be expressed as a cubic (where the cubic term is zero). The end points of the cubic will be the same as the quadratic’s. CP0 = QP0 CP3 = QP2 The two control points for the cubic are: CP1 = QP0 + 2/3 *(QP1-QP0) CP2 = QP2 + 2/3 … Read more

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