//The method which draws the boundingbox's edges
private void DrawBoundingBox(BoundingBoxBuffers buffers, BasicEffect effect, GraphicsDevice graphicsDevice, Matrix view, Matrix projection)
{
graphicsDevice.SetVertexBuffer(buffers.Vertices);
graphicsDevice.Indices = buffers.Indices;
effect.World = Matrix.Identity;
effect.View = view;
effect.Projection = projection;
foreach (EffectPass pass in effect.CurrentTechnique.Passes)
{
pass.Apply();
graphicsDevice.DrawIndexedPrimitives(PrimitiveType.LineList, 0, 0, buffers.VertexCount, 0, buffers.PrimitiveCount);
}
}
//This method builds the drawable object related to the boundingbox limits
private BoundingBoxBuffers CreateBoundingBoxBuffers(BoundingBox bBox, GraphicsDevice graphicsDevice)
{
BoundingBoxBuffers boundingBoxBuffers = new BoundingBoxBuffers();
boundingBoxBuffers.PrimitiveCount = 24;
boundingBoxBuffers.VertexCount = 48;
VertexBuffer vertexBuffer = new VertexBuffer(graphicsDevice,
typeof(VertexPositionColor), boundingBoxBuffers.VertexCount,
BufferUsage.WriteOnly);
List<VertexPositionColor> vertices = new List<VertexPositionColor>();
const float ratio = 5.0f;
Vector3 xOffset = new Vector3((bBox.Max.X - bBox.Min.X) / ratio, 0, 0);
Vector3 yOffset = new Vector3(0, (bBox.Max.Y - bBox.Min.Y) / ratio, 0);
Vector3 zOffset = new Vector3(0, 0, (bBox.Max.Z - bBox.Min.Z) / ratio);
Vector3[] corners = bBox.GetCorners();
// Corner 1.
AddVertex(vertices, corners[0]);
AddVertex(vertices, corners[0] + xOffset);
AddVertex(vertices, corners[0]);
AddVertex(vertices, corners[0] - yOffset);
AddVertex(vertices, corners[0]);
AddVertex(vertices, corners[0] - zOffset);
// Corner 2.
AddVertex(vertices, corners[1]);
AddVertex(vertices, corners[1] - xOffset);
AddVertex(vertices, corners[1]);
AddVertex(vertices, corners[1] - yOffset);
AddVertex(vertices, corners[1]);
AddVertex(vertices, corners[1] - zOffset);
// Corner 3.
AddVertex(vertices, corners[2]);
AddVertex(vertices, corners[2] - xOffset);
AddVertex(vertices, corners[2]);
AddVertex(vertices, corners[2] + yOffset);
AddVertex(vertices, corners[2]);
AddVertex(vertices, corners[2] - zOffset);
// Corner 4.
AddVertex(vertices, corners[3]);
AddVertex(vertices, corners[3] + xOffset);
AddVertex(vertices, corners[3]);
AddVertex(vertices, corners[3] + yOffset);
AddVertex(vertices, corners[3]);
AddVertex(vertices, corners[3] - zOffset);
// Corner 5.
AddVertex(vertices, corners[4]);
AddVertex(vertices, corners[4] + xOffset);
AddVertex(vertices, corners[4]);
AddVertex(vertices, corners[4] - yOffset);
AddVertex(vertices, corners[4]);
AddVertex(vertices, corners[4] + zOffset);
// Corner 6.
AddVertex(vertices, corners[5]);
AddVertex(vertices, corners[5] - xOffset);
AddVertex(vertices, corners[5]);
AddVertex(vertices, corners[5] - yOffset);
AddVertex(vertices, corners[5]);
AddVertex(vertices, corners[5] + zOffset);
// Corner 7.
AddVertex(vertices, corners[6]);
AddVertex(vertices, corners[6] - xOffset);
AddVertex(vertices, corners[6]);
AddVertex(vertices, corners[6] + yOffset);
AddVertex(vertices, corners[6]);
AddVertex(vertices, corners[6] + zOffset);
// Corner 8.
AddVertex(vertices, corners[7]);
AddVertex(vertices, corners[7] + xOffset);
AddVertex(vertices, corners[7]);
AddVertex(vertices, corners[7] + yOffset);
AddVertex(vertices, corners[7]);
AddVertex(vertices, corners[7] + zOffset);
vertexBuffer.SetData(vertices.ToArray());
boundingBoxBuffers.Vertices = vertexBuffer;
IndexBuffer indexBuffer = new IndexBuffer(graphicsDevice, IndexElementSize.SixteenBits, boundingBoxBuffers.VertexCount, BufferUsage.WriteOnly);
indexBuffer.SetData(Enumerable.Range(0, boundingBoxBuffers.VertexCount).Select(i => (short)i).ToArray());
boundingBoxBuffers.Indices = indexBuffer;
return boundingBoxBuffers;
}