private static void RasterizeBlockingSplines(TerrainComponent terrain, TerrainVegetationComponent component, PixelBuffer mask, int maskChannel, float terrainOffset)
{
foreach (var spline in component.BlockingSplines)
{
var vertices = new FastList <Splines.VertexPositionNormalTangentColorTexture>();
var indices = new FastList <int>();
Splines.SplineMeshBuilder.CreateSplineMesh(spline, vertices, indices);
for (var i = 0; i < indices.Count; i += 3)
{
var vt1f = vertices[indices[i + 0]].Position;
var vt2f = vertices[indices[i + 1]].Position;
var vt3f = vertices[indices[i + 2]].Position;
vt1f = (vt1f + terrainOffset) / terrain.Size * mask.Width;
vt2f = (vt2f + terrainOffset) / terrain.Size * mask.Width;
vt3f = (vt3f + terrainOffset) / terrain.Size * mask.Width;
// Just ignore Y axis, works well enoguh for splines but if we
// support generic volumes in the future then we might want to project it a bit more properly
// or maybe just do an offscreen render pass on the gpu ...
var vt1 = new Int2((int)vt1f.X, (int)vt1f.Z);
var vt2 = new Int2((int)vt2f.X, (int)vt2f.Z);
var vt3 = new Int2((int)vt3f.X, (int)vt3f.Z);
// Calculate bounding box
var maxX = Math.Max(vt1.X, Math.Max(vt2.X, vt3.X));
var minX = Math.Min(vt1.X, Math.Min(vt2.X, vt3.X));
var maxY = Math.Max(vt1.Y, Math.Max(vt2.Y, vt3.Y));
var minY = Math.Min(vt1.Y, Math.Min(vt2.Y, vt3.Y));
// Triangle intersection
var vs1 = vt2 - vt1;
var vs2 = vt3 - vt1;
for (var x = minX; x <= maxX; x++)
{
for (var y = minY; y < maxY; y++)
{
var q = new Int2(x - vt1.X, y - vt1.Y);
var s = (float)CrossProduct(q, vs2) / CrossProduct(vs1, vs2);
var t = (float)CrossProduct(vs1, q) / CrossProduct(vs1, vs2);
if (s >= 0 && t >= 0 && (s + t) <= 1)
{
var currentPixel = mask.GetPixel <Color>(x, y);
currentPixel[maskChannel] = 0;
mask.SetPixel <Color>(x, y, currentPixel);
}
}
}
}
}
}
/// <summary>
/// Update and recreate a page if necessary
/// </summary>
private void UpdatePages(TerrainComponent terrain, TerrainVegetationComponent component, TerrainVegetationRenderData renderData)
{
if (renderData.Pages != null && renderData.MaskImage != null && !component.IsDirty)
{
return;
}
if (renderData.MaskImage == null || renderData.Mask != component.Mask)
{
renderData.Mask = component.Mask;
renderData.MaskImage?.Dispose();
// Get mask image data
try
{
var game = Services.GetService <IGame>();
var graphicsContext = game.GraphicsContext;
var commandList = graphicsContext.CommandList;
renderData.MaskImage = component.Mask.GetDataAsImage(commandList);
}
catch
{
// Image probably not loaded yet .. try again next frame :)
return;
}
}
// Cache render data so we won't need to recreate pages
var mask = renderData.MaskImage.PixelBuffer[0];
var maskChannel = (int)component.MaskChannel;
// Calculate terrain center offset
var terrainOffset = terrain.Size / 2.0f;
RasterizeBlockingSplines(terrain, component, mask, maskChannel, terrainOffset);
// Create vegetation pages
var rng = new Random(component.Seed);
var pagesPerRow = (int)terrain.Size / PageSize;
var instancesPerRow = (int)(PageSize * component.Density);
var distancePerInstance = PageSize / (float)instancesPerRow;
renderData.Pages = new TerrainVegetationPage[pagesPerRow * pagesPerRow];
var scaleRange = component.MaxScale - component.MinScale;
for (var pz = 0; pz < pagesPerRow; pz++)
{
for (var px = 0; px < pagesPerRow; px++)
{
var radius = PageSize * 0.5f;
var pagePosition = new Vector3(px * PageSize - terrainOffset, 0, pz * PageSize - terrainOffset);
var page = new TerrainVegetationPage();
renderData.Pages[pz * pagesPerRow + px] = page;
for (var iz = 0; iz < instancesPerRow; iz++)
{
for (var ix = 0; ix < instancesPerRow; ix++)
{
var position = pagePosition;
position.X += ix * distancePerInstance;
position.Z += iz * distancePerInstance;
position.X += (float)rng.NextDouble() * distancePerInstance * 2.0f - distancePerInstance;
position.Z += (float)rng.NextDouble() * distancePerInstance * 2.0f - distancePerInstance;
position.Y = terrain.GetHeightAt(position.X, position.Z);
var tx = (int)((position.X + terrainOffset) / terrain.Size * mask.Width);
var ty = (int)((position.Z + terrainOffset) / terrain.Size * mask.Height);
if (tx < 0 || tx >= mask.Width || ty < 0 || ty >= mask.Height)
{
continue;
}
var maskDensity = mask.GetPixel <Color>(tx, ty)[maskChannel] / 255.0;
if (rng.NextDouble() > maskDensity)
{
continue;
}
var normal = terrain.GetNormalAt(position.X, position.Z);
var slope = 1.0f - Math.Abs(normal.Y);
if (slope < component.MinSlope || slope > component.MaxSlope)
{
continue;
}
var scale = (float)rng.NextDouble() * scaleRange + component.MinScale;
var rotation = Quaternion.RotationAxis(Vector3.UnitY, (float)rng.NextDouble() * MathUtil.TwoPi) * Quaternion.BetweenDirections(Vector3.UnitY, normal);
var scaling = new Vector3(scale);
Matrix.Transformation(ref scaling, ref rotation, ref position, out var transformation);
page.Instances.Add(transformation);
}
}
page.WorldPosition = pagePosition + new Vector3(radius, 0, radius);
}
}
component.IsDirty = false;
}
public bool IsDirty(TerrainComponent component) => Material != component.Material || Size != component.Size || Heightmap != component.Heightmap || Mesh == null;
public void Update(TerrainComponent component)
{
Size = component.Size;
Material = component.Material;
Heightmap = component.Heightmap;
}