// UpdateViewportCanvas will render the 3D scene with 2D polygons with transforming all 3D points to 2D coordinates
// It will render all children of ObjectsRootVisual3D (to render all children of Viewport3D, use MainViewport.Children)
// The method is static so it can be easily copied to some other location for some other testing
private static void UpdateViewportCanvas(Visual3DCollection visuals, BaseCamera camera, Canvas viewportCanvas, bool fillPolygon)
{
// Get camera's view and projection matrixes
Matrix3D viewMatrix, projectionMatrix;
camera.GetCameraMatrixes(out viewMatrix, out projectionMatrix);
// Calculate combined viewProjection matrix
Matrix3D viewProjectionMatrix3D = viewMatrix * projectionMatrix;
// Read target canvas size and its center point (half the size)
double viewportCanvasWidth = viewportCanvas.ActualWidth;
double viewportCanvasHeight = viewportCanvas.ActualHeight;
double viewportCanvasCenterX = viewportCanvasWidth * 0.5;
double viewportCanvasCenterY = viewportCanvasHeight * 0.5;
// Clear all existing Polygons
viewportCanvas.Children.Clear();
// IterateGeometryModel3DObjects will traverse the Visual3D and Model3DGroup objects
// and will call the callback delegate for each GeometryModel3D.
// The callback delegate also receives the transformation that were applied to the parents of the GeometryModel3D.
// If you want to be called for each ModelVisual3D, use the IterateModelVisualsObjects method
Ab3d.Utilities.ModelIterator.IterateGeometryModel3DObjects(visuals : visuals,
parentTransform3D : null, // optionally we can specify the initial transformation
callback : delegate(GeometryModel3D geometryModel3D, Transform3D parentTransform3D)
{
// This is called for each GeometryModel3D in the hierarchy
var meshGeometry3D = geometryModel3D.Geometry as MeshGeometry3D;
if (meshGeometry3D == null)
{
return;
}
var positions = meshGeometry3D.Positions;
var triangleIndices = meshGeometry3D.TriangleIndices;
if (positions == null || positions.Count == 0 || triangleIndices == null || triangleIndices.Count == 0)
{
return;
}
// Get fill brush from material
var materialBrush = GetMaterialBrush(geometryModel3D.Material);
// If this geometryModel3D has any transformation, combine it with the parentTransform3D - this will be the world transformation for this geometryModel3D
var worldTransform = CombineTransform(parentTransform3D, geometryModel3D.Transform);
Matrix3D worldViewProjectionMatrix3D;
// Get final worldViewProjectionMatrix3D
if (worldTransform == null || worldTransform.Value.IsIdentity)
{
worldViewProjectionMatrix3D = viewProjectionMatrix3D;
}
else
{
worldViewProjectionMatrix3D = worldTransform.Value * viewProjectionMatrix3D;
}
var triangleIndicesCount = triangleIndices.Count;
// Go through all triangles
for (int i = 0; i < triangleIndicesCount; i += 3)
{
// Read positions for one triangle
Point3D p1 = positions[triangleIndices[i]];
Point3D p2 = positions[triangleIndices[i + 1]];
Point3D p3 = positions[triangleIndices[i + 2]];
// Transform to homogeneous coordinates (to get final x and y we need to divide them by w)
Point4D h1 = worldViewProjectionMatrix3D.Transform(new Point4D(p1.X, p1.Y, p1.Z, 1));
Point4D h2 = worldViewProjectionMatrix3D.Transform(new Point4D(p2.X, p2.Y, p2.Z, 1));
Point4D h3 = worldViewProjectionMatrix3D.Transform(new Point4D(p3.X, p3.Y, p3.Z, 1));
// Do a simple clip test - if any position is behind the camera we will not render this triangle
if (h1.Z < 0 || h2.Z < 0 || h3.Z < 0)
{
return;
}
// Convert to screen coordinates by dividing by w and then adjust to the size of canvas (we also invert y)
Point canvas1 = new Point((h1.X * viewportCanvasWidth) / (2 * h1.W) + viewportCanvasCenterX,
viewportCanvasHeight - ((h1.Y * viewportCanvasHeight) / (2 * h1.W) + viewportCanvasCenterY)); // invert y
Point canvas2 = new Point((h2.X * viewportCanvasWidth) / (2 * h2.W) + viewportCanvasCenterX,
viewportCanvasHeight - ((h2.Y * viewportCanvasHeight) / (2 * h2.W) + viewportCanvasCenterY));
Point canvas3 = new Point((h3.X * viewportCanvasWidth) / (2 * h3.W) + viewportCanvasCenterX,
viewportCanvasHeight - ((h3.Y * viewportCanvasHeight) / (2 * h3.W) + viewportCanvasCenterY));
// Create triangle
// TODO: This creates many Polyline objects on each change of camera - to improve performance it would be possible to reuse the existing Polylines and just change the position's coordinates
var points = new PointCollection(3);
points.Add(canvas1);
points.Add(canvas2);
points.Add(canvas3);
var polyline = new Polygon()
{
Points = points,
StrokeThickness = 1,
StrokeMiterLimit = 1
};
if (fillPolygon)
{
polyline.Fill = materialBrush;
polyline.Stroke = Brushes.Black;
}
else
{
polyline.Fill = null;
polyline.Stroke = materialBrush;
}
viewportCanvas.Children.Add(polyline);
}
});
}