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Drawing SVG

Loading a composition and drawing it can be done as follows:

fun main() = application {
    program {
        val composition = loadSVG("data/drawing.svg")
        extend {
            drawer.composition(composition)
        }
    }
}

Note that OPENRNDR’s support for SVG files works best with SVG files that are saved in the Tiny SVG 1.x profile .

When drawing a composition from SVG you will notice that fill and stroke colors from the SVG file are used over the Drawer colors.

Compositions

Here a Composition is a tree structure with Composition.root as its root node.

CompositionNode types
Node Type Function
GroupNode Holds multiple child nodes in children
ShapeNode Holds a a single shape in shape
TextNode Holds text (currently not implemented)
ImageNode Holds an image (currently not implemented)
CompositionNode The base class for composition node
CompositionNode properties
Property name Property type Description
transform Matrix44 local transformation
fill CompositionColor fill color
stroke CompositionColor stroke color
id String? node id
parent CompositionNode? node parent
effectiveFill (read-only) ColorRGBa? the effective fill color, potentially inherited from ancestor
effectiveStroke(read-only) ColorRGBa? the effective stroke color, potentially inherited from ancestor
GroupNode properties
Property name Property type Description
children MutableList<CompositionNode> child nodes
ShapeNode properties
Property name Property type Description
shape Shape a single shape

Querying the composition

Finding all shapes in the composition

val shapeNodes = composition.findShapes()

Modifying the composition

Since a Composition contains many immutable parts it is easier to (partially) replace parts of the composition.

val m = translate(1.0, 0.0, 0.0);
composition.root.map {
  if (it is ShapeNode) {
    it.copy(shape=it.shape.transform(m))
  } else {
    it
  }
}

Creating compositions manually

Compositions are tree structures that can be constructed manually. Below you find an example of constructing a Composition in code.

val root = GroupNode()
val composition = Composition(root)
val shape = Circle(200.0, 200.0, 100.0).shape
val shapeNode = ShapeNode(shape)
shapeNode.fill = ColorRGBa.PINK
shapeNode.stroke = ColorRGBa.BLACK
// -- add shape node to root
root.children.add(shapeNode)

Composition Drawer

OPENRNDR has a much more convenient interface for creating Compositions. The idea behind this interface is that it works in a similar way to Drawer.

Below we use drawComposition {} to reproduce the same composition as in the previous example.

val composition = drawComposition {
    fill = ColorRGBa.PINK
    stroke = ColorRGBa.BLACK
    circle(Vector2(100.0, 100.0), 50.0)
}

Transforms

Transforms work in the same way as in Drawer

val composition = drawComposition {
    fill = ColorRGBa.PINK
    stroke = ColorRGBa.BLACK
    isolated {
        for (i in 0 until 100) {
            circle(Vector2(0.0, 0.0), 50.0)
            translate(50.0, 50.0)
        }
    }
}

Saving compositions to SVG

Compositions can be saved to SVG using the saveToFile function.

// -- load in a composition
val composition = loadSVG("data/example.svg")
composition.saveToFile(File("output.svg"))

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