void ParticlePool::BuildVertexData()
{
Matrix4 transform = matViewInv;
Matrix3 localRot = transform.GetRotationMatrix();
// 计算顶点法线信息
Vector3f normal = localRot * Vector3f(0.0f, 0.0f, 1.0f);
// 每帧构造新的顶点缓冲，用于渲染
std::vector<Particle>::iterator iter = m_Particles.begin();
for (unsigned int i=0; i<m_ActiveParticleCount; i++, iter++)
{
// 更新顶点颜色
float new_color[16];
for (int j=0; j<4; j++)
memcpy(&(new_color[j*4]), iter->m_Color.GetArray(), sizeof(float) * 4);
m_VertexBuffer->ModifyVertexData(VFormat_Color, 16 * i/*iter->m_VertexOffset*/, sizeof(float) * 16, new_color);
Vector3f points[4] = { Vector3f(-0.5f, 0.5f, 0.0f),
Vector3f(0.5f, 0.5f, 0.0f),
Vector3f(-0.5f, -0.5f, 0.0f),
Vector3f(0.5f, -0.5f, 0.0f) };
float new_pos[12];
float new_normal[12];
// 生成billboard顶点的方向
transform.SetPosition(iter->m_Position);
Matrix3 rotMat = Matrix3::BuildRollRotationMatrix(iter->spin);
for (int j=0; j<4; j++)
{
// 根据缩放等属性计算顶点位置信息
Vector3f point = rotMat * (points[j] * iter->scale);
//point.z = iter->m_ZOffset;
point.x *= iter->m_ScreenScaleX;
point.y *= iter->m_ScreenScaleY;
point = transform * point;
//point += iter->m_Position;
memcpy(&new_pos[j*3], point.GetArray(), sizeof(float) * 3);
memcpy(&new_normal[j*3], normal.GetArray(), sizeof(float) * 3);
}
m_VertexBuffer->ModifyVertexData(VFormat_Position, 12 * i/*iter->m_VertexOffset*/, sizeof(float) * 12, new_pos);
m_VertexBuffer->ModifyVertexData(VFormat_Normal, 12 * i, sizeof(float) * 12, new_normal);
float uv[] = { 0.0f, 1.0f,
1.0f, 1.0f,
0.0f, 0.0f,
1.0f, 0.0f };
m_VertexBuffer->ModifyVertexData(VFormat_Texcoord0, 8 * i, sizeof(float) * 8, uv);
}
// 更新索引缓冲数据，处理有效粒子数目变化的情况
m_IndexBuffer->SetIndexSize(m_ActiveParticleCount * 2);
iter = m_Particles.begin();
for (unsigned int i=0; i<m_ActiveParticleCount; i++, iter++)
{
//unsigned int offset = iter->m_IndexOffset;
unsigned int index[6] = { i * 4, 2 + i * 4, 1 + i * 4,
2 + i * 4, 3 + i * 4, 1 + i * 4 };
m_IndexBuffer->ModifyIndexData(6 * i, sizeof(unsigned int) * 6, index);
}
}
