ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working in three dimensions (3D)
}
}
}
t1 = focalLength/(focalLength + z1);
t2 = focalLength/(focalLength + z2);
t3 = focalLength/(focalLength + z3);
t4 = focalLength/(focalLength + z4);
// determine triangle vertices based on t values
var vertices:Vector. = new Vector.();
vertices.push(x1*t1,y1*t1, x2*t2,y2*t2, x3*t3,y3*t3, x4*t4,y4*t4);
// set T values allowing perspective to change
// as each vertex moves around in z space
var uvtData:Vector. = new Vector.();
uvtData.push(0,0,t1, 1,0,t2, 1,1,t3, 0,1,t4);
// draw
container.graphics.clear();
container.graphics.beginBitmapFill(bitmapData);
container.graphics.drawTriangles(vertices, indices, uvtData);
To test this example, save these two class files in the same directory as an image named “ocean.jpg”. You can see how
the original bitmap is transformed to appear as if it is vanishing in the distance and rotating in 3D space.
Culling
Flash Player 10 and later, Adobe AIR 1.5 and later
Culling is the process that determines which surfaces of a three-dimensional object the renderer should not render
because they are hidden from the current viewpoint. In 3D space, the surface on the “back” of a three-dimensional
object is hidden from the viewpoint:
A
B
The back of a 3D object is hidden from the viewpoint.
A. viewpoint B. 3D object C. the back of a three dimensional object
C
Inherently all triangles are always rendered no matter their size, shape, or position. Culling insures that Flash Player
or AIR renders your 3D object correctly. In addition, to save on rendering cycles, sometimes you want some triangles
to be skipped by the render. Consider a cube rotating in space. At any given time, you'll never see more than three sides
of that cube since the sides not in view would be facing the other direction on the other side of the cube. Since those
sides are not going to be seen, the renderer shouldn't draw them. Without culling, Flash Player or AIR renders both
the front and back sides.
Last updated 6/6/2012
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