private void CalculateVertexStep(int instanceCount)
{
for (int i = 0; i < instanceCount; i++)
{
foreach (var instancedAttribute in InstancedAttributes[_activeVertexShader])
{
SetAttribute(_activeVertexShader, instancedAttribute.Key, instancedAttribute.Value[i]);
}
for (int j = 0; j < RenderData[ActiveVAO].Count; j++)
{
foreach (var attribute in Attributes[_activeVertexShader])
{
SetAttribute(_activeVertexShader, attribute.Key, attribute.Value[(int)RenderData[ActiveVAO][j]]);
}
_activeVertexShader.Main();
_vertexPositions.Add(_activeVertexShader.Position * (1 / _activeVertexShader.Position.W));
foreach (var outValue in _activeVertexShader.GetOutValues())
{
if (_vertexValues.ContainsKey(outValue.Key))
{
_vertexValues[outValue.Key].Add(outValue.Value);
}
else
{
_vertexValues.Add(outValue.Key, new List <object> {
outValue.Value
});
}
}
}
}
}
public void Draw(Matrix4x4 modelMat, Camera cam)
{
this.Cam = cam;
var viewMat =
Matrix4x4.GenEulerMat(cam.euler.x, cam.euler.y, cam.euler.z) *
Matrix4x4.GenTranslateMat(cam.translate.x, cam.translate.y, cam.translate.z);
var projMat = Matrix4x4.GenFrustum(cam.fov, cam.aspect, cam.near, cam.far);
var mvpMat = projMat * viewMat * modelMat;
// set built-in shader vairables：我们内置的shader变量，都可以再这输入
VertexShader.Mats[0] = mvpMat;
// vs transformations, 顶点着色器处理，一般就将顶点坐标变换到：clip pos
foreach (var vertex in Vertices)
{
VertexShader.dc = vertex;
VertexShader.Main();
}
// ndc pos : Normalized Device Coordinates position，直译为：归一化设备坐标，“设备”两字可去掉，重点就是“归一化”，所以又叫“归一化坐标”
foreach (var vertex in Vertices)
{ // perspective divide : 透视除法，除了clipPos坐标，其他fragmentShader的输入参数，需要插值处理的，都处理透视除法
vertex.invCamZ = 1 / vertex.clipPos.w; // jave.lin : inverse camera z，因为在proj矩阵m[4,3]==-1，然后投影矩阵相乘后，可将camera space下的顶点的z存于clipPos.w中
vertex.ndcPos = vertex.clipPos * vertex.invCamZ;
#if PC
vertex.inColor = vertex.color * vertex.invCamZ;
vertex.inUV = vertex.uv * vertex.invCamZ;
#endif
}
// win pos：窗口坐标变换（或叫映射也行）
foreach (var vertex in Vertices)
{
vertex.winPos = Vector4.Get(
Viewport.X + (vertex.ndcPos.x * 0.5f + 0.5f) * Viewport.Width,
Viewport.Y + (1 - (vertex.ndcPos.y * 0.5f + 0.5f)) * Viewport.Height,
vertex.clipPos.w, // cam z
1);
}
// primitive assembly：图元装配，这里只支持三角形
triangleList.Clear();
for (int i = 0; i < Indices.Count; i += 3)
{
var idx0 = Indices[i];
var idx1 = Indices[i + 1];
var idx2 = Indices[i + 2];
var t = new Triangle {
dc0 = Vertices[idx0], dc1 = Vertices[idx1], dc2 = Vertices[idx2]
};
triangleList.Add(t);
}
// clip：简单的裁剪处理，正常的裁剪需要对图元不同类型做不同处理，处理部分在裁剪视椎外的需要剪掉，然后再视椎内边缘生成对应的新的顶点
foreach (var t in triangleList)
{
if (shouldClip(t.dc0.ndcPos) || shouldClip(t.dc1.ndcPos) || shouldClip(t.dc2.ndcPos))
{
t.clip = true; continue;
}
}
// facing-cull：面向剔除
foreach (var t in triangleList)
{
if (FaceCull && faceClip(t))
{
t.clip = true; continue;
}
}
// rasterize and fs：栅格化+片段着色器处理
foreach (var t in triangleList)
{
if (t.clip)
{
continue;
}
if (Wireframe)
{
Rasterizer.DrawLine(t.dc0, t.dc1, this);
Rasterizer.DrawLine(t.dc1, t.dc2, this);
Rasterizer.DrawLine(t.dc2, t.dc0, this);
}
else
{
Rasterizer.DrawTriangle(t, this);
}
}
}