// Perform rendering on a specific context
public void Render(CRenderContext Context)
{
if (!Visible)
{
return;
}
// Calculate transform matrix
TMat4x4 Mat = GetTransformMatrix(Context);
// Calculate the inverse matrix
TMat4x4 InverseMat = Mat.FindInverseMat();
// Clear translation effect
InverseMat.ClearTranslation();
// Calculate the viewer position in object coordinates
TVertex ViewDirection = Context.GetViewDirection();
TVertex ViewerPosInObjCoords = InverseMat.MulVertex(ViewDirection);
float PerspectiveFactor = Context.GetPerspectiveFactor();
Color IlluminatedFaceColor;
foreach (TFace3D Face in FaceTable)
{
bool FaceVisible;
float FaceDotProd = 0;
if (!Context.IsBackfaceCullingMode())
{
// No backface culling, the face is always visible
FaceVisible = true;
}
else
{
// Do backface culling
FaceDotProd = Math3D.DotProduct(ViewerPosInObjCoords, Face.Normal);
// Perspective mode
if (Context.IsPerspectiveMode())
{
// Remember if the face is visible
FaceVisible = (FaceDotProd > THRESHOLD_FOR_CULLING);
}
else
{
FaceVisible = (FaceDotProd > 0);
}
}
if (FaceVisible)
{
// Get current face vertices and transform to world coordinates
TVertex[] FaceVertex = new TVertex[3] {
Mat.MulVertex(VertexTable[Face.AIndex]),
Mat.MulVertex(VertexTable[Face.BIndex]),
Mat.MulVertex(VertexTable[Face.CIndex])
};
Point[] ScreenCoords = new Point[3];
if (TestForBackClipping(FaceVertex[0], FaceVertex[1], FaceVertex[2]))
{
bool PreventFaceDraw = false;
// Perspective mode
if (Context.IsPerspectiveMode())
{
// Transform the from world coordinates to screen coordinates
for (int i = 0; i < 3; i++)
{
if (Math.Abs(FaceVertex[i].Z) < POLYGON_Z_MIN_VALUE)
{
PreventFaceDraw = true;
break;
}
ScreenCoords[i].X = (int)(FaceVertex[i].X * PerspectiveFactor / FaceVertex[i].Z);
ScreenCoords[i].Y = (int)(FaceVertex[i].Y * PerspectiveFactor / FaceVertex[i].Z);
if ((Math.Abs(ScreenCoords[i].X) > POLYGON_COORD_MAX_VALUE) || (Math.Abs(ScreenCoords[i].Y) > POLYGON_COORD_MAX_VALUE))
{
PreventFaceDraw = true;
break;
}
}
}
else
// Orthogonal projection
{
PreventFaceDraw = false;
// Transform the from world coordinates to screen coordinates
for (int i = 0; i < 3; i++)
{
ScreenCoords[i].X = (int)(FaceVertex[i].X / ORTHO_PROJECTION_SCALING);
ScreenCoords[i].Y = (int)(FaceVertex[i].Y / ORTHO_PROJECTION_SCALING);
}
}
if (!PreventFaceDraw)
{
T2DTriangle ScreenTriangle = new T2DTriangle(ScreenCoords[0], ScreenCoords[1], ScreenCoords[2]);
if (Context.IsWireFrameMode())
{
Context.DrawTriangle(ScreenTriangle);
}
else
// Filled triangles mode
{
float LightLevel = FaceDotProd + MIN_LIGHT_LEVEL;
// Clip to maximum light level
if (LightLevel > 1.0)
{
LightLevel = 1.0f;
}
// Calculate face color
int ARGBColor = ClipColorChn(Face.Color.R, LightLevel);
ARGBColor |= ClipColorChn(Face.Color.G, LightLevel) << 8;
ARGBColor |= ClipColorChn(Face.Color.B, LightLevel) << 16;
// Set maximum alpha channel value
ARGBColor = (int)((uint)ARGBColor | 0xff000000);
IlluminatedFaceColor = Color.FromArgb(ARGBColor);
// Calculate factors for the polygon filling routine
TVertex FaceNormal = Math3D.CalcFaceNormal(FaceVertex[0], FaceVertex[1], FaceVertex[2]);
float M, N, K;
CalculatePolygonFactors(FaceNormal, FaceVertex[1], PerspectiveFactor, out M, out N, out K);
TriangleFiller.DrawFilledTriangle(ScreenTriangle, Context, IlluminatedFaceColor, M, N, K);
}
}
}
}
}
RenderChildObjects(Context);
}
