private bool CalculateNormals()
{
// Create a temporary array to hold the un-normalized normal verctors.
var normals = new Vector3[(TerrainHeight - 1) * (TerrainWidth - 1)];
// Go through all the faces in the mesh and calculate their normals.
for (var j = 0; j < (TerrainHeight - 1); j++)
{
for (var i = 0; i < (TerrainWidth - 1); i++)
{
var index1 = (j * TerrainHeight) + i;
var index2 = (j * TerrainHeight) + (i + 1);
var index3 = ((j + 1) * TerrainHeight) + i;
// Get three vertices from the face.
var vertex1 = new[] { HeightMap[index1].x, HeightMap[index1].y, HeightMap[index1].z };
var vertex2 = new[] { HeightMap[index2].x, HeightMap[index2].y, HeightMap[index2].z };
var vertex3 = new[] { HeightMap[index3].x, HeightMap[index3].y, HeightMap[index3].z };
// Calculate the two vectors for this face.
var vector1 = new[]
{
vertex1[0] - vertex3[0],
vertex1[1] - vertex3[1],
vertex1[2] - vertex3[2]
};
var vector2 = new[]
{
vertex3[0] - vertex2[0],
vertex3[1] - vertex2[1],
vertex3[2] - vertex2[2]
};
var index = (j * (TerrainHeight - 1)) + i;
// Calculate the cross product of those two vectors to get the un-normalized value for this face normal.
normals[index] = new Vector3()
{
X = (vector1[1] * vector2[2]) - (vector1[2] * vector2[1]),
Y = (vector1[2] * vector2[0]) - (vector1[0] * vector2[2]),
Z = (vector1[0] * vector2[1]) - (vector1[1] * vector2[0])
};
}
}
// Now go through all the vertices and take an average of each face normal
// that the vertex touches to get the averaged normal fot that vertex.
for (var j = 0; j < (TerrainHeight - 1); j++)
{
for (var i = 0; i < (TerrainWidth - 1); i++)
{
int index;
// Initialize the sum
var sum = new[] { 0f, 0f, 0f };
// Initialize the count
var count = 0;
// Bottom left face
if (((i - 1) >= 0) && ((j - 1) >= 0))
{
index = ((j - 1) * (TerrainHeight - 1)) + (i - 1);
sum[0] += normals[index].X;
sum[1] += normals[index].Y;
sum[2] += normals[index].Z;
count++;
}
// Bottom right face
if ((i < (TerrainWidth - 1)) && ((j - 1) >= 0))
{
index = ((j - 1) * (TerrainHeight - 1)) + i;
sum[0] += normals[index].X;
sum[1] += normals[index].Y;
sum[2] += normals[index].Z;
count++;
}
// Upper left face
if (((i - 1) >= 0) && (j < (TerrainHeight - 1)))
{
index = (j * (TerrainHeight - 1)) + i;
sum[0] += normals[index].X;
sum[1] += normals[index].Y;
sum[2] += normals[index].Z;
count++;
}
// Upper right face
if ((i < (TerrainWidth - 1)) && (j < (TerrainHeight - 1)))
{
index = (j * (TerrainHeight - 1)) + i;
sum[0] += normals[index].X;
sum[1] += normals[index].Y;
sum[2] += normals[index].Z;
count++;
}
// Take the average of the faces touching this vertex.
sum[0] /= count;
sum[1] /= count;
sum[2] /= count;
// Calculate the length of this normal.
var length = (float)Math.Sqrt(sum[0] * sum[0] + sum[1] * sum[1] + sum[2] * sum[2]);
// Get the index to the vertex location in the height map array.
index = (j * TerrainHeight) + i;
// Normalize the final share normal fot this vertex and store it in the height map array.
var heightMap = HeightMap[index];
heightMap.nx = sum[0] / length;
heightMap.ny = sum[1] / length;
heightMap.nz = sum[2] / length;
HeightMap[index] = heightMap;
}
}
return true;
}
private bool UpdateBuffers(DeviceContext deviceContext, int positionX, int positionY)
{
// If the position we rendering this bitmap to has not changed then don't update the vertex buffer since it.
if (positionX == PreviousPosX && positionY == PreviousPosY)
return true;
// If it has changed then update the position it is being rendered to.
PreviousPosX = positionX;
PreviousPosY = positionY;
// Calculate the screen coordinates of the left side of the bitmap.
var left = (-(ScreenWidth >> 1)) + (float)positionX;
// Calculate the screen coordinates of the right side of the bitmap.
var right = left + BitmapWidth;
// Calculate the screen coordinates of the top of the bitmap.
var top = (ScreenHeight >> 1) - (float)positionY;
// Calculate the screen coordinates of the bottom of the bitmap.
var bottom = top - BitmapHeight;
// Create and load the vertex array.
var vertices = new[]
{
new TextureShader.Vertex()
{
position = new Vector3(left, top, 0),
texture = new Vector2(0, 0)
},
new TextureShader.Vertex()
{
position = new Vector3(right, bottom, 0),
texture = new Vector2(1, 1)
},
new TextureShader.Vertex()
{
position = new Vector3(left, bottom, 0),
texture = new Vector2(0, 1)
},
new TextureShader.Vertex()
{
position = new Vector3(left, top, 0),
texture = new Vector2(0, 0)
},
new TextureShader.Vertex()
{
position = new Vector3(right, top, 0),
texture = new Vector2(1, 0)
},
new TextureShader.Vertex()
{
position = new Vector3(right, bottom, 0),
texture = new Vector2(1, 1)
}
};
DataStream mappedResource;
#region Vertex Buffer
// Lock the vertex buffer so it can be written to.
deviceContext.MapSubresource(VertexBuffer, MapMode.WriteDiscard, SharpDX.Direct3D11.MapFlags.None, out mappedResource);
// Copy the data into the vertex buffer.
mappedResource.WriteRange<TextureShader.Vertex>(vertices);
// Unlock the vertex buffer.
deviceContext.UnmapSubresource(VertexBuffer, 0);
#endregion
return true;
}
