void ProcessScanLine(DetailsForShading details)
{
var gradient1 = details.pa.Y != details.pb.Y ? (details.currentY - details.pa.Y) / (details.pb.Y - details.pa.Y) : 1;
var gradient2 = details.pc.Y != details.pd.Y ? (details.currentY - details.pc.Y) / (details.pd.Y - details.pc.Y) : 1;
int sx = (int)Interpolate(details.pa.X, details.pb.X, gradient1);
int ex = (int)Interpolate(details.pc.X, details.pd.X, gradient2);
// starting Z & ending Z
float z1 = Interpolate(details.pa.Z, details.pb.Z, gradient1);
float z2 = Interpolate(details.pc.Z, details.pd.Z, gradient2);
// drawing a line from left (sx) to right (ex)
for (var x = sx; x < ex; x++)
{
float gradient = (x - sx) / (float)(ex - sx);
var z = Interpolate(z1, z2, gradient);
Vertex current = new Vertex();
current.Coordinates = new Vector3(x, details.currentY, z);
Color color = shadingMachine.GetColorPerPixel(current, details);
DrawPoint(current.Coordinates, color);
}
}
public override DetailsForShading GetDetailsForShading(Vertex v1, Vertex v2, Vertex v3)
{
DetailsForShading details = new DetailsForShading();
details.v1 = v1;
details.v2 = v2;
details.v3 = v3;
details.area = CalculateArea(v1.Coordinates, v2.Coordinates, v3.Coordinates);
details.lightParameters = meshLightParameters;
return(details);
}
public override Color GetColorPerPixel(Vertex vertex, DetailsForShading details)
{
(double alpha, double beta, double gamma) = CalculateAlphaBetaGammaForVertex(vertex.Coordinates, details);
float r = (float)(alpha * details.v1Color.R / 255 + beta * details.v2Color.R / 255 + gamma * details.v3Color.R / 255);
float g = (float)(alpha * details.v1Color.G / 255 + beta * details.v2Color.G / 255 + gamma * details.v3Color.G / 255);
float b = (float)(alpha * details.v1Color.B / 255 + beta * details.v2Color.B / 255 + gamma * details.v3Color.B / 255);
int R = (int)(r * 255);
int G = (int)(g * 255);
int B = (int)(b * 255);
(R, G, B) = ValidateRGB(R, G, B);
return(Color.FromArgb(R, G, B));
}
public override DetailsForShading GetDetailsForShading(Vertex v1, Vertex v2, Vertex v3)
{
DetailsForShading details = new DetailsForShading();
details.v1Color = ComputeColorPerVertex(v1);
details.v2Color = ComputeColorPerVertex(v2);
details.v3Color = ComputeColorPerVertex(v3);
details.v1 = v1;
details.v2 = v2;
details.v3 = v3;
details.area = CalculateArea(v1.Coordinates, v2.Coordinates, v3.Coordinates);
return(details);
}
public override Color GetColorPerPixel(Vertex vertex, DetailsForShading details)
{
(double alpha, double beta, double gamma) = CalculateAlphaBetaGammaForVertex(vertex.Coordinates, details);
Vector3 normal = (float)alpha * details.v1.Normal + (float)beta * details.v2.Normal + (float)gamma * details.v3.Normal;
normal.Normalize();
Vector3 wcoordinates = (float)alpha * details.v1.WorldCoordinates + (float)beta * details.v2.WorldCoordinates + (float)gamma * details.v3.WorldCoordinates;
vertex.Normal = normal;
vertex.WorldCoordinates = wcoordinates;
Color color = ComputeColorPerVertex(vertex);
return(color);
}
public override DetailsForShading GetDetailsForShading(Vertex v1, Vertex v2, Vertex v3)
{
Vector3 vNormal = (v1.Normal + v2.Normal + v3.Normal) / 3;
Vector3 vCenterPoint = (v1.WorldCoordinates + v2.WorldCoordinates + v3.WorldCoordinates) / 3;
Vertex v = new Vertex();
v.Normal = vNormal;
v.WorldCoordinates = vCenterPoint;
DetailsForShading details = new DetailsForShading();
details.globalColor = ComputeColorPerVertex(v);
return(details);
}
public void DrawTriangle(Vertex v1, Vertex v2, Vertex v3, MeshLightParameters lightParameters)
{
// Sorting the points in order to always have this order on screen p1, p2 & p3
// with p1 always up (thus having the Y the lowest possible to be near the top screen)
// then p2 between p1 & p3
if (v1.Coordinates.Y > v2.Coordinates.Y)
{
var temp = v2;
v2 = v1;
v1 = temp;
}
if (v2.Coordinates.Y > v3.Coordinates.Y)
{
var temp = v2;
v2 = v3;
v3 = temp;
}
if (v1.Coordinates.Y > v2.Coordinates.Y)
{
var temp = v2;
v2 = v1;
v1 = temp;
}
Vector3 p1 = v1.Coordinates;
Vector3 p2 = v2.Coordinates;
Vector3 p3 = v3.Coordinates;
DetailsForShading details = shadingMachine.GetDetailsForShading(v1, v2, v3);
// computing lines' directions
float dP1P2, dP1P3;
// http://en.wikipedia.org/wiki/Slope
// Computing slopes
if (p2.Y - p1.Y > 0)
{
dP1P2 = (p2.X - p1.X) / (p2.Y - p1.Y);
}
else
{
dP1P2 = 0;
}
if (p3.Y - p1.Y > 0)
{
dP1P3 = (p3.X - p1.X) / (p3.Y - p1.Y);
}
else
{
dP1P3 = 0;
}
// First case where triangles are like that:
// P1
// -
// --
// - -
// - -
// - - P2
// - -
// - -
// -
// P3
if (dP1P2 > dP1P3)
{
for (var y = (int)p1.Y; y <= (int)p3.Y; y++)
{
//data.currentY = y;
details.currentY = y;
if (y < p2.Y)
{
details.pa = v1.Coordinates;
details.pb = v3.Coordinates;
details.pc = v1.Coordinates;
details.pd = v2.Coordinates;
//ProcessScanLine(data, v1, v3, v1, v2, details.globalColor);
ProcessScanLine(details);
}
else
{
details.pa = v1.Coordinates;
details.pb = v3.Coordinates;
details.pc = v2.Coordinates;
details.pd = v3.Coordinates;
// ProcessScanLine(data, v1, v3, v2, v3, details.globalColor);
ProcessScanLine(details);
}
}
}
// First case where triangles are like that:
// P1
// -
// --
// - -
// - -
// P2 - -
// - -
// - -
// -
// P3
else
{
for (var y = (int)p1.Y; y <= (int)p3.Y; y++)
{
//data.currentY = y;
details.currentY = y;
if (y < p2.Y)
{
details.pa = v1.Coordinates;
details.pb = v2.Coordinates;
details.pc = v1.Coordinates;
details.pd = v3.Coordinates;
//ProcessScanLine(data, v1, v2, v1, v3, details.globalColor);
ProcessScanLine(details);
}
else
{
details.pa = v2.Coordinates;
details.pb = v3.Coordinates;
details.pc = v1.Coordinates;
details.pd = v3.Coordinates;
// ProcessScanLine(data, v2, v3, v1, v3, details.globalColor);
ProcessScanLine(details);
}
}
}
}
public abstract Color GetColorPerPixel(Vertex vertex, DetailsForShading details);
public override Color GetColorPerPixel(Vertex vertex, DetailsForShading details)
{
return(details.globalColor);
}
protected (double alpha, double beta, double gamma) CalculateAlphaBetaGammaForVertex(Vector3 v, DetailsForShading details)
{
double a, b, g;
double areaA, areaB, areaG;
areaA = CalculateArea(v, details.v2.Coordinates, details.v3.Coordinates);
areaB = CalculateArea(v, details.v1.Coordinates, details.v3.Coordinates);
areaG = CalculateArea(v, details.v1.Coordinates, details.v2.Coordinates);
a = areaA / details.area;
b = areaB / details.area;
g = areaG / details.area;
return(a, b, g);
}
