/// <summary>
/// Function to create the vertex data for the sphere.
/// </summary>
/// <param name="vertexData">Pointer to the buffer that will hold the vertex data.</param>
/// <param name="indexData">Pointer to the buffer that will hold the index data.</param>
/// <param name="radius">Radius of the sphere.</param>
/// <param name="textureCoordinates">Texture coordinates for the sphere.</param>
/// <param name="ringCount">Number of rings in the sphere.</param>
/// <param name="segmentCount">Number of segments in the sphere.</param>
private void GetVertices(GorgonNativeBuffer <Vertex3D> vertexData,
GorgonNativeBuffer <int> indexData,
float radius,
RectangleF textureCoordinates,
int ringCount,
int segmentCount)
{
int index = 0; // Current index.
int vertexOffset = 0;
int indexOffset = 0;
float deltaRingAngle = ((float)System.Math.PI) / ringCount;
float deltaSegAngle = (((float)System.Math.PI) * 2.0f) / segmentCount;
Radius = radius;
// Build our sphere.
for (int ring = 0; ring <= ringCount; ring++)
{
float ringAngle = ring * deltaRingAngle;
radius = ringAngle.Sin() * 0.5f * Radius;
float radiusY = ringAngle.Cos() * Radius * 0.5f;
for (int segment = 0; segment <= segmentCount; segment++)
{
var textureDelta = new DX.Vector2(1.0f - (segment / (float)segmentCount), ring / (float)ringCount);
float segmentAngle = deltaSegAngle * segment;
var position = new DX.Vector3(radius * segmentAngle.Sin(), radiusY, radius * segmentAngle.Cos());
DX.Vector3.Multiply(ref position, 2.0f, out DX.Vector3 normal);
DX.Vector3.TransformCoordinate(ref position, ref _orientation, out position);
DX.Vector3.TransformCoordinate(ref normal, ref _orientation, out normal);
normal.Normalize();
// Create the vertex.
textureDelta.X *= textureCoordinates.Width;
textureDelta.Y *= textureCoordinates.Height;
textureDelta.X += textureCoordinates.X;
textureDelta.Y += textureCoordinates.Y;
vertexData[vertexOffset++] = new Vertex3D
{
Position = new DX.Vector4(position, 1.0f),
UV = textureDelta,
Normal = normal
};
// Add the indices and skip the last ring.
if (ring == ringCount)
{
continue;
}
indexData[indexOffset++] = (index + segmentCount + 1);
indexData[indexOffset++] = index;
indexData[indexOffset++] = (index + segmentCount);
indexData[indexOffset++] = (index + segmentCount + 1);
indexData[indexOffset++] = (index + 1);
indexData[indexOffset++] = index;
index++;
}
}
}
/// <summary>
/// Function to calculate tangent information for bump mapping.
/// </summary>
/// <param name="vertexData">Buffer holding the vertices.</param>
/// <param name="indexData">Buffer holding the indices.</param>
protected void CalculateTangents(GorgonNativeBuffer <Vertex3D> vertexData, GorgonNativeBuffer <int> indexData)
{
var biTanData = new DX.Vector3[VertexCount];
var tanData = new DX.Vector3[VertexCount];
int indexOffset = 0;
for (int i = 0; i < TriangleCount; ++i)
{
int index1 = indexData[indexOffset++];
// If we hit a strip-restart index, then skip to the next index.
if ((PrimitiveType == PrimitiveType.TriangleStrip) &&
(index1 < 0))
{
index1 = indexData[indexOffset++];
}
int index2 = indexData[indexOffset++];
int index3 = indexData[indexOffset++];
Vertex3D vertex1 = vertexData[index1];
Vertex3D vertex2 = vertexData[index2];
Vertex3D vertex3 = vertexData[index3];
DX.Vector4.Subtract(ref vertex2.Position, ref vertex1.Position, out DX.Vector4 deltaPos1);
DX.Vector4.Subtract(ref vertex3.Position, ref vertex1.Position, out DX.Vector4 deltaPos2);
DX.Vector2.Subtract(ref vertex2.UV, ref vertex1.UV, out DX.Vector2 deltaUV1);
DX.Vector2.Subtract(ref vertex3.UV, ref vertex1.UV, out DX.Vector2 deltaUV2);
float denom = ((deltaUV1.X * deltaUV2.Y) - (deltaUV1.Y * deltaUV2.X));
float r = 0.0f;
if (!denom.EqualsEpsilon(0))
{
r = 1.0f / denom;
}
var tangent = new DX.Vector3(((deltaUV2.Y * deltaPos1.X) - (deltaUV1.Y * deltaPos2.X)) * r,
((deltaUV2.Y * deltaPos1.Y) - (deltaUV1.Y * deltaPos2.Y)) * r,
((deltaUV2.Y * deltaPos1.Z) - (deltaUV1.Y * deltaPos2.Z)) * r);
var biTangent = new DX.Vector3(((deltaUV1.X * deltaPos2.X) - (deltaUV2.X * deltaPos1.X)) * r,
((deltaUV1.X * deltaPos2.Y) - (deltaUV2.X * deltaPos1.Y)) * r,
((deltaUV1.X * deltaPos2.Z) - (deltaUV2.X * deltaPos1.Z)) * r);
DX.Vector3.Add(ref tanData[index1], ref tangent, out tanData[index1]);
DX.Vector3.Add(ref tanData[index2], ref tangent, out tanData[index2]);
DX.Vector3.Add(ref tanData[index3], ref tangent, out tanData[index3]);
DX.Vector3.Add(ref biTanData[index1], ref biTangent, out biTanData[index1]);
DX.Vector3.Add(ref biTanData[index2], ref biTangent, out biTanData[index2]);
DX.Vector3.Add(ref biTanData[index3], ref biTangent, out biTanData[index3]);
}
for (int i = 0; i < VertexCount; ++i)
{
Vertex3D vertex = vertexData[i];
DX.Vector3.Dot(ref vertex.Normal, ref tanData[i], out float dot);
DX.Vector3.Multiply(ref vertex.Normal, dot, out DX.Vector3 tangent);
DX.Vector3.Subtract(ref tanData[i], ref tangent, out tangent);
DX.Vector3.Normalize(ref tangent, out tangent);
DX.Vector3.Cross(ref vertex.Normal, ref tanData[i], out DX.Vector3 cross);
DX.Vector3.Dot(ref cross, ref biTanData[i], out dot);
vertexData[i] = new Vertex3D
{
Position = vertex.Position,
Normal = vertex.Normal,
UV = vertex.UV,
Tangent = new DX.Vector4(tangent, dot < 0.0f ? -1.0f : 1.0f)
};
}
}
