/// <summary>
/// configures vertex color to the vertex component data
/// using the billboard object.
/// </summary>
/// <param name="vertexData">target vertex component data</param>
/// <param name="obj">source billboard object</param>
/// <param name="startIndex">start index of the vertex component data</param>
private static void SetBufferColor(ref VertexPositionColorTexture[] vertexData,
BillboardObject obj, int startIndex)
{
for (int i = 0; i < 4; i++)
{
vertexData[startIndex + i].Color = obj.Color;
}
}
/// <summary>
/// create billboard objects using the texture.
/// </summary>
/// <param name="count">billboard object count</param>
/// <param name="texture">texture resource</param>
/// <param name="renderingSpace">3D render space</param>
/// <param name="alwaysUpdate"></param>
public void Create(int count, Texture2D texture, RenderingSpace renderingSpace,
bool alwaysUpdate)
{
this.objectCount = count;
this.renderingSpace = renderingSpace;
this.alwaysUpdate = alwaysUpdate;
// create billboard objects.
for (int i = 0; i < count; i++)
{
BillboardObject obj = new BillboardObject();
obj.AddUpdateType(BillboardObject.UpdateTypes.Enable);
billboardList.Add(obj);
}
base.Create(count * vertexStride, count * indexStride, texture);
}
/// <summary>
/// configures texture coordinates to the vertex component data
/// using the billboard object.
/// </summary>
/// <param name="vertexData">target vertex component data</param>
/// <param name="obj">source billboard object</param>
/// <param name="startIndex">start index of the vertex component data</param>
/// <param name="renderingSpace">3D render space</param>
private static void SetBufferTextureCoord(
ref VertexPositionColorTexture[] vertexData, BillboardObject obj,
int startIndex, RenderingSpace renderingSpace)
{
float u1 = 0.0f, v1 = 0.0f, u2 = 0.0f, v2 = 0.0f;
u1 = obj.MinUV.X;
v1 = obj.MinUV.Y;
u2 = obj.MaxUV.X;
v2 = obj.MaxUV.Y;
if (renderingSpace == RenderingSpace.Screen)
{
float swap = v1;
v1 = v2;
v2 = swap;
}
vertexData[startIndex + 0].TextureCoordinate = new Vector2(u1, v2);
vertexData[startIndex + 1].TextureCoordinate = new Vector2(u1, v1);
vertexData[startIndex + 2].TextureCoordinate = new Vector2(u2, v2);
vertexData[startIndex + 3].TextureCoordinate = new Vector2(u2, v1);
}
/// <summary>
/// configures a position vector to the vertex component data
/// using the billboard object.
/// </summary>
/// <param name="vertexData">target vertex component data</param>
/// <param name="obj">source billboard object</param>
/// <param name="startIndex">start index of the vertex component data</param>
/// <param name="ay">position vector</param>
private static void SetBufferPosition(
ref VertexPositionColorTexture[] vertexData, BillboardObject obj,
int startIndex, Vector3 ay)
{
Vector3 by = Vector3.Zero;
float cy = obj.Size * 0.5f;
by = ay * cy;
// [0] [1]
// +-------------+
// | |
// +c |
// | |
// +-------------+
// [2] [3]
// 0 2 1 - 1 2 3
vertexData[startIndex + 0].Position = obj.Start - by;
vertexData[startIndex + 1].Position = obj.End - by;
vertexData[startIndex + 2].Position = obj.Start + by;
vertexData[startIndex + 3].Position = obj.End + by;
}
/// <summary>
/// configures vertex color to the vertex component data
/// using the billboard object.
/// </summary>
/// <param name="vertexData">target vertex component data</param>
/// <param name="obj">source billboard object</param>
/// <param name="startIndex">start index of the vertex component data</param>
private static void SetBufferColor(ref VertexPositionColorTexture[] vertexData,
BillboardObject obj, int startIndex)
{
for (int i = 0; i < 4; i++)
vertexData[startIndex + i].Color = obj.Color;
}
/// <summary>
/// configures texture coordinates to the vertex component data
/// using the billboard object.
/// </summary>
/// <param name="vertexData">target vertex component data</param>
/// <param name="obj">source billboard object</param>
/// <param name="startIndex">start index of the vertex component data</param>
/// <param name="renderingSpace">3D render space</param>
private static void SetBufferTextureCoord(
ref VertexPositionColorTexture[] vertexData, BillboardObject obj,
int startIndex, RenderingSpace renderingSpace)
{
float u1 = 0.0f, v1 = 0.0f, u2 = 0.0f, v2 = 0.0f;
u1 = obj.MinUV.X;
v1 = obj.MinUV.Y;
u2 = obj.MaxUV.X;
v2 = obj.MaxUV.Y;
if (renderingSpace == RenderingSpace.Screen)
{
float swap = v1;
v1 = v2;
v2 = swap;
}
vertexData[startIndex + 0].TextureCoordinate = new Vector2(u1, v2);
vertexData[startIndex + 1].TextureCoordinate = new Vector2(u1, v1);
vertexData[startIndex + 2].TextureCoordinate = new Vector2(u2, v2);
vertexData[startIndex + 3].TextureCoordinate = new Vector2(u2, v1);
}
/// <summary>
/// configures a position vector to the vertex component data
/// using the billboard object.
/// </summary>
/// <param name="vertexData">target vertex component data</param>
/// <param name="obj">source billboard object</param>
/// <param name="startIndex">start index of the vertex component data</param>
/// <param name="ay">position vector</param>
private static void SetBufferPosition(
ref VertexPositionColorTexture[] vertexData, BillboardObject obj,
int startIndex, Vector3 ay)
{
Vector3 by = Vector3.Zero;
float cy = obj.Size * 0.5f;
by = ay * cy;
// [0] [1]
// +-------------+
// | |
// +c |
// | |
// +-------------+
// [2] [3]
// 0 2 1 - 1 2 3
vertexData[startIndex + 0].Position = obj.Start - by;
vertexData[startIndex + 1].Position = obj.End - by;
vertexData[startIndex + 2].Position = obj.Start + by;
vertexData[startIndex + 3].Position = obj.End + by;
}
/// <summary>
/// create billboard objects using the texture.
/// </summary>
/// <param name="count">billboard object count</param>
/// <param name="texture">texture resource</param>
/// <param name="renderingSpace">3D render space</param>
/// <param name="alwaysUpdate"></param>
public void Create(int count, Texture2D texture, RenderingSpace renderingSpace,
bool alwaysUpdate)
{
this.objectCount = count;
this.renderingSpace = renderingSpace;
this.alwaysUpdate = alwaysUpdate;
// create billboard objects.
for (int i = 0; i < count; i++)
{
BillboardObject obj = new BillboardObject();
obj.AddUpdateType(BillboardObject.UpdateTypes.Enable);
billboardList.Add(obj);
}
base.Create(count * vertexStride, count * indexStride, texture);
}
/// <summary>
/// updates the vertex data and draws
/// It always looks at the view matrix at the center between
/// the begin point and the end point of the billboard.
/// </summary>
/// <param name="renderTracer">render information</param>
protected override void OnDraw(RenderTracer renderTracer)
{
int count = 0;
for (int i = 0; i < objectCount; i++)
{
if (billboardList[i].Enable == false)
{
continue;
}
count++;
}
if (count == 0)
{
return;
}
PrimitiveCount = count * 2;
UpdateVertexCount = objectCount * vertexStride;
// needs to update?
if (renderTracer.View != lastViewMatrix)
{
needToUpdate = true;
this.lastViewMatrix = renderTracer.View;
}
if (alwaysUpdate || needToUpdate)
{
int vertexOffset = 0;
int indexOffset = 0;
// calculates inverse view matrix.
Matrix billboardMatrix = this.TransformedMatrix * renderTracer.View;
billboardMatrix = Helper3D.Transpose(billboardMatrix);
// gets inverse view direction.
Vector3 invertViewAt = billboardMatrix.Forward;
invertViewAt.Normalize();
for (int i = 0; i < objectCount; i++)
{
BillboardObject obj = billboardList[i];
if (obj.Enable == false)
{
continue;
}
Vector3 vec = Vector3.Zero;
Vector3 dir = Vector3.Zero;
dir = obj.End - obj.Start;
dir.Normalize();
Vector3.Cross(ref dir, ref invertViewAt, out vec);
vec.Normalize();
// updates vertex positions.
SetBufferPosition(ref vertexData, obj, vertexOffset, vec);
// updates texture coordinates.
SetBufferTextureCoord(ref vertexData, obj, vertexOffset,
renderingSpace);
// updates vertex colors.
SetBufferColor(ref vertexData, obj, vertexOffset);
indexData[indexOffset + 0] = (short)(vertexOffset + 0);
indexData[indexOffset + 1] = (short)(vertexOffset + 2);
indexData[indexOffset + 2] = (short)(vertexOffset + 1);
indexData[indexOffset + 3] = (short)(vertexOffset + 1);
indexData[indexOffset + 4] = (short)(vertexOffset + 2);
indexData[indexOffset + 5] = (short)(vertexOffset + 3);
vertexOffset += vertexStride;
indexOffset += indexStride;
}
if (userPrimitive == false)
{
// binds the vertex buffer.
BindVertexBuffer();
// binds the index buffer.
BindIndexBuffer();
}
if (needToUpdate)
{
needToUpdate = false;
}
}
// draws mesh
base.OnDraw(renderTracer);
}
