Script, basic concepts math spiral

[rickiiy]

Hello
win 8.1
QCAD/CAM Professional 3.14.0.1
Revision: b77f907


I'm new to scripting in Qcad where I'm having problems getting a simplistic parabola to draw on the sheet. I've used the spiral example as a template but it is creating the drawing parametrically where as I would just like to draw the simple function f(x)=x^2.
I think my problem in in my approach to which classes I should be using but unfortunately the tutorials and reference is not making this clear to me.
Please look at the code below and any suggestions to get me started would be appreciated. Thanks

include("../MathExamples.js");

/**
* This action draws a simple spiral (center at 0/0).
*/
function parabolic(guiAction) {
MathExamples.call(this, guiAction);
}

parabolic.prototype = new MathExamples();

/**
* Draws a spiral and terminates.
*/
parabolic.prototype.beginEvent = function() {
MathExamples.prototype.beginEvent.call(this);

var document = this.getDocument();
var di = this.getDocumentInterface();

var operation = new RAddObjectsOperation(true);
// see the spiral example as this has changed
var xDelta = 0.1;
var c = 0;

for (var x = -10.0; x < 10 ; x += xDelta) {
var lineData = new RLineData(
new RVector(
Math.pow(x, 2)
)
);
var line = new RLineEntity(document, lineData);
operation.addObject(line);
// ++c;
// x += xDelta;
}
di.applyOperation(operation);

this.terminate();
};

/**
* Adds a menu for this action to Examples/Math Examples/Spiral.
*/
parabolic.init = function(basePath) {
var action = new RGuiAction(qsTr("&Parab"), RMainWindowQt.getMainWindow());
action.setRequiresDocument(true);
action.setScriptFile(basePath + "/parabolic.js");
action.setGroupSortOrder(79700);
action.setSortOrder(100);
action.setWidgetNames(["MathExamplesMenu"]);
};

[andrew]

var lineData = new RLineData(new RVector(Math.pow(x, 2)));

RLineData needs two RVector arguments (start and end point).
RVector needs two number arguments (x and y).

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var lineData = new RLineData(new RVector(someXValue, someYValue), new RVector(Math.pow(x, 2), y));

Where someXValue, someYValue are your x,y values for the start point of the line.

You might find it easer to use the QCAD simple API:

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addLine(x1, y1, x2, y2);

or for a single polyline:

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addPolyline([x1, y1, x2, y2, x3, y3, ...]);

No need for operations, etc. in the QCAD Simple API.

[rickiiy]

Thanks Andrew,

That was most helpful and I feel a bit foolish for not picking that up.
What I didn't realize was that the spiral script was creating a lot of small line segments
Anyway my first ever script is now working with the code block below. (probably not that efficiently)

var xDelta = 0.1;
for (var x = -10.0; x < 10 ; x += xDelta) {
var lineData = new RLineData(
new RVector( x - xDelta , Math.pow(x - xDelta, 2)), //start point
new RVector( x, Math.pow(x, 2)) // end point
);
var line = new RLineEntity(document, lineData);
operation.addObject(line);

}

[andrew]

If you want to produce a polyline instead, you can use the following approach:

Code: Select all

var vertices = [];
for (...) {
    vertices.push([x, y]);
}
addPolyline(vertices);