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In Processing, we can arrange points, lines, surfaces, and volumes (objects in 0, 1, 2, and 3 dimensions, respectively) ina 3D space or, where this makes sense in the 2D space of the image window. The number of parameters of the object primitiveswill determine if these objects have to be positioned in the X-Y or in the X-Y-Z space.
point() is the simplest of the graphic
primitives. When invoked with two coordinate parameters, itpositions a point in the X-Y space. When invoked with three
coordinate parameters, it positions a point in the X-Y-Zspace. A point, in geometric sense, does not have dimension,
but it can be assigned an occupation in pixels and a color, bythe functions
strokeWeight() and
stroke() , respectively. For example, the simple
Processing sketch
stroke(180,0,0);
strokeWeight(10);point(60,60); draws a dot in the image window.
beginShape(POINTS) and
endShape() . Between them each point has to
be specified with the
vertex() function. Transformations of rotation, translation, and
scaling do not apply to the inside of composite objectsdescribed with
beginShape() and
endShape() , but they can precede the definition
of a composite object and apply to the whole.
line() draws a line segment between two
points in the plane or the 3D space, with width and color thatcan be set with
strokeWeight() and
stroke() , respectively.
beginShape() and
endShape() . Between them, vertices are listed by
calls to the function
vertex() . Using the
invocation
beginShape(LINES) the vertices are
taken in couples, each identifying a segment. With the argument-freeinvocation
beginShape() the vertices,
taken one after the other, define a polygonal line. With theclosure
endShape(CLOSE) the line is
closed on itself by linking the first and lastvertices. The color of such polygon can be set by using the
fill() function or, conversely, left equal to the background color with the
noFill() .
curve() , when called with eight parameters, draws
a curve on the image plane, with initial and final pointsdetermined, respectively, by the second and third couple of
coordinates passed as arguments. The first and last couple ofcoordinates define two control points for the curve, which is
an interpolating spline, thus passing for all four points. In Processing, however, only the curve segment between the intermediate points is visualized.
curveVertex() to specify each
point in the block delimited by
beginShape() and
endShape() .
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