public void Render(Camera cam, bool orthographic, bool backfaceCulling, float scale, DepthTexture texture, Position3D modelPosition)
{
//make a copy, don't touch original points to keep accuracy
TriangleData tDataTmp = tData;
//move the vertices in local space
ScaleVertices(ref tDataTmp, scale);
RotateVertices(ref tDataTmp, modelPosition);
TranslateVerticesLocal(ref tDataTmp, modelPosition);
//move the vertices in world space
TranslateVerticesWorld(ref tDataTmp, cam.CameraPosition);
RotateVertices(ref tDataTmp, cam.CameraPosition);
//culling/drawing/perspective
if (InZRange(tDataTmp, cam.FarClippingPlane))
{
if (!orthographic)
{
PerspectiveVertices(ref tDataTmp, cam.ScreenDepthTexture, cam.CalculatedFov);
}
if (backfaceCulling && NotFacingCamera(tDataTmp))
{
return;
}
DrawTriangle(tDataTmp, texture, cam.ScreenDepthTexture);
}
}
//Check if its in the screenTexture area. Left/right/... are the bounding box of the triangle limited to screen space.
//Returns False if not in screen screenTexture area.
private bool OnScreen(TriangleData tData, DepthTexture screenTexture, ref int left, ref int right, ref int top, ref int bottom)
{
left = (int)Left(tData);
if (left > screenTexture.Width)
{
return(false);
}
right = (int)Right(tData);
if (right < 0)
{
return(false);
}
top = (int)Top(tData);
if (top > screenTexture.Height)
{
return(false);
}
bottom = (int)Bottom(tData);
if (bottom < 0)
{
return(false);
}
left = Math.Max(0, left);
right = Math.Min(screenTexture.Width, right);
top = Math.Max(0, top);
bottom = Math.Min(screenTexture.Height, bottom);
return(true);
}
private void ScaleVertices(ref TriangleData tData, float scale)
{
if (scale != 1.0f)
{
tData.Vertex1.Scale(scale);
tData.Vertex2.Scale(scale);
tData.Vertex3.Scale(scale);
}
}
private int Area(TriangleData tData)
{
int x1 = (int)tData.Vertex1.x;
int y1 = (int)tData.Vertex1.y;
int x2 = (int)tData.Vertex2.x;
int y2 = (int)tData.Vertex2.y;
int x3 = (int)tData.Vertex3.x;
int y3 = (int)tData.Vertex3.y;
return(x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2));
}
private void PerspectiveVertices(ref TriangleData tData, DepthTexture screenTexture, float calculatedFov)
{
if (tData.Vertex1.z > 0)
{
tData.Vertex1.Perspective(calculatedFov, screenTexture.HalfWidth, screenTexture.HalfHeight);
}
if (tData.Vertex2.z > 0)
{
tData.Vertex2.Perspective(calculatedFov, screenTexture.HalfWidth, screenTexture.HalfHeight);
}
if (tData.Vertex3.z > 0)
{
tData.Vertex3.Perspective(calculatedFov, screenTexture.HalfWidth, screenTexture.HalfHeight);
}
}
private void TranslateVerticesLocal(ref TriangleData tData, Position3D delta)
{
tData.Vertex1.TranslateLocal(delta);
tData.Vertex2.TranslateLocal(delta);
tData.Vertex3.TranslateLocal(delta);
}
//triangle render tools
private void RotateVertices(ref TriangleData tData, Position3D angle)
{
tData.Vertex1.Rotate(angle);
tData.Vertex2.Rotate(angle);
tData.Vertex3.Rotate(angle);
}
public BaseTriangle(TriangleData tData)
{
this.tData = tData;
}
private void DrawTriangle(TriangleData tData, DepthTexture modelTexture, DepthTexture screenTexture)
{
//set array boundes
int left = 0;
int right = 0;
int top = 0;
int bottom = 0;
if (!OnScreen(tData, screenTexture, ref left, ref right, ref top, ref bottom))
{
return; //cull out triangles not in screen space
}
//setup values for the draw loop
int x1 = (int)tData.Vertex1.x;
int y1 = (int)tData.Vertex1.y;
float z1 = tData.Vertex1.z;
int x2 = (int)tData.Vertex2.x;
int y2 = (int)tData.Vertex2.y;
float z2 = tData.Vertex2.z;
int x3 = (int)tData.Vertex3.x;
int y3 = (int)tData.Vertex3.y;
float z3 = tData.Vertex3.z;
//precomputed values
int totalArea = Math.Abs(Area(tData));
if (totalArea < 1)
{
return; //filter subpixel triangles
}
//precompute area pt1
int y2my3 = y2 - y3;
int y3my1 = y3 - y1;
int y1my2 = y1 - y2;
//computing uvs
float uvX1 = tData.Uv1.u * modelTexture.Width;
float uvX2 = tData.Uv2.u * modelTexture.Width;
float uvX3 = tData.Uv3.u * modelTexture.Width;
float uvY1 = tData.Uv1.v * modelTexture.Height;
float uvY2 = tData.Uv2.v * modelTexture.Height;
float uvY3 = tData.Uv3.v * modelTexture.Height;
//draw loop
for (int y = top; y < bottom; y++)
{
//precompute area pt2
int apre = x2 * (y3 - y) + x3 * (y - y2);
int bpre = x1 * (y - y3) + x3 * (y1 - y);
int cpre = x1 * (y2 - y) + x2 * (y - y1);
bool inTriangle = false; //right side exit scanline optimization
for (int x = left; x < right; x++)
{
//find out what points are in the triangle with the precompute area
int ba = Math.Abs(x * y2my3 + apre);
int bb = Math.Abs(x * y3my1 + bpre);
int bc = Math.Abs(x * y1my2 + cpre);
if (ba + bb + bc <= totalArea)
{
inTriangle = true;
//interpolate pixel amounts
float a = ba / (float)totalArea;
float b = bb / (float)totalArea;
float c = 1 - (a + b);
//get the uv/depth
int u = (int)(uvX1 * a + uvX2 * b + uvX3 * c);
int v = (int)(uvY1 * a + uvY2 * b + uvY3 * c);
float depth = z1 * a + z2 * b + z3 * c;
//set the pixel if passes depth test
screenTexture.SetPixelDepthTest(x, y, modelTexture.GetPixel(u, v), depth);
}
else
if (inTriangle)
{
break; //end scanline if exiting right side of the triangle
}
}
}
}
private float Bottom(TriangleData tData)
{
return(MathTools.Max3(tData.Vertex1.y, tData.Vertex2.y, tData.Vertex3.y));
}
private float Top(TriangleData tData)
{
return(MathTools.Min3(tData.Vertex1.y, tData.Vertex2.y, tData.Vertex3.y));
}
private float Right(TriangleData tData)
{
return(MathTools.Max3(tData.Vertex1.x, tData.Vertex2.x, tData.Vertex3.x));
}
private float Left(TriangleData tData)
{
return(MathTools.Min3(tData.Vertex1.x, tData.Vertex2.x, tData.Vertex3.x));
}
private float MinZ(TriangleData tData)
{
return(MathTools.Min3(tData.Vertex1.z, tData.Vertex2.z, tData.Vertex3.z));
}
private bool NotFacingCamera(TriangleData tData)
{
return(Area(tData) > -1);
}
private bool InZRange(TriangleData tData, float farClippingPlane)
{
return(!(MaxZ(tData) < 0 || MinZ(tData) > farClippingPlane));
}