private void Render(ref ShaderVariables shader, IEnumerable <Triangle> tris, IUvMap?uvs, Material material)
{
var backwards = this.Backward;
foreach (var tri in tris)
{
var worldTri = tri.Transform(shader.ModelToWorld); // Convert to world space
shader.WorldNormal = worldTri.Normal;
// Backface culling
if (!material.TwoSided)
{
var normal = worldTri.Normal;
if (Vec3.Dot(backwards, normal) < -0.1)
{
continue;
}
}
// Get triangles
var v1 = WorldToScreenPoint(worldTri.Item1);
var v2 = WorldToScreenPoint(worldTri.Item2);
var v3 = WorldToScreenPoint(worldTri.Item3);
// Get the UV coordinates
Vec2 uv1 = (uvs != null) ? uvs[tri.Item1] : Vec2.Zero;
Vec2 uv2 = (uvs != null) ? uvs[tri.Item2] : Vec2.Zero;
Vec2 uv3 = (uvs != null) ? uvs[tri.Item3] : Vec2.Zero;
Rasterize(ref shader, worldTri, v1, v2, v3, uv1, uv2, uv3, material);
}
}
private void DrawVertex(Vec3 world, Vec3 screen, Vec2 uv, Material material, ref ShaderVariables vars)
{
vars.WorldPosition = world;
vars.ScreenPixel = screen;
vars.UVCoordinates = uv;
var colour = material.Vert(vars);
SetPixel(screen, colour);
}
/// <summary>
/// Shader to apply to each face's surface
/// </summary>
/// <param name="variables">shading variables</param>
/// <returns>color of point on face</returns>
public override Color Fragment(ShaderVariables variables)
{
var surfColour = ColourSample(variables.UVCoordinates);
Vec3 N = variables.WorldNormal;
var tint = variables.LightSources.Select((light) => {
var lightColour = light.Tint;
Vec3 L = light.Direction(variables.WorldPosition, variables.WorldNormal);
double Lintensity = light.Intensity(variables.WorldPosition, variables.WorldNormal);
double diffuse_surface_shade = (Albedo / Math.PI) * Lintensity * Math.Max(Vec3.Dot(L, N), 0);
return(Darken(lightColour, diffuse_surface_shade));
}).Aggregate((a, b) => Mix(a, b));
return(Mix(surfColour, tint));
}
/// <summary>
/// Render the given scene to the pixel buffer
/// </summary>
/// <param name="scene">scene to render</param>
public void Render(Scene scene)
{
// Clean data
ClearPixels();
ClearDepth();
// Set constant shader properties
var vars = new ShaderVariables();
vars.WorldCameraPosition = this.Position;
vars.LightSources = scene.OfType <LightSource>().ToList().AsReadOnly();
// Loop over all models
foreach (var renderable in scene.OfType <IRenderable>())
{
vars.ModelToWorld = renderable.LocalToWorldMatrix;
if (renderable.Mesh != null && renderable.Material != null)
{
Render(ref vars, renderable.Mesh, renderable.UVs, (Material)renderable.Material);
}
}
}
/// <summary>
/// Shader to apply to each face's edges
/// </summary>
/// <param name="variables">shading variables</param>
/// <returns>edge colour</returns>
public override Color Edge(ShaderVariables variables)
{
return(Colour);
}
/// <summary>
/// Shader to apply to each face's surface
/// </summary>
/// <param name="variables">shading variables</param>
/// <returns>color of point on face</returns>
public virtual Color Fragment(ShaderVariables variables)
{
return(Color.Transparent);
}
/// <summary>
/// Shader to apply to each face's edges
/// </summary>
/// <param name="variables">shading variables</param>
/// <returns>edge colour</returns>
public virtual Color Edge(ShaderVariables variables)
{
return(Fragment(variables));
}
/// <summary>
/// Shader to apply to each face's surface
/// </summary>
/// <param name="variables">shading variables</param>
/// <returns>color of point on face</returns>
public override Color Fragment(ShaderVariables variables)
{
return(ColourSample(variables.UVCoordinates));
}
/// <summary>
/// Shader to apply to each face's edges
/// </summary>
/// <param name="variables">shading variables</param>
/// <returns>edge colour</returns>
public override Color Edge(ShaderVariables variables)
{
return(Fragment(variables));
}
/// <summary>
/// Shader to apply to each face's surface
/// </summary>
/// <param name="variables">shading variables</param>
/// <returns>color of point on face</returns>
public override Color Fragment(ShaderVariables variables)
{
return(Colour);
}
private void DrawFlatTopTriangle(Vec3 worldV1, Vec3 worldV2, Vec3 worldV3, Vec3 a, Vec3 b, Vec3 c, Vec2 uva, Vec2 uvb, Vec2 uvc, Material img, ref ShaderVariables shader)
{
double invslope1 = (c.X - a.X) / (c.Y - a.Y);
double invslope2 = (c.X - b.X) / (c.Y - b.Y);
double leftX = Math.Floor(c.X);
double rightX = Math.Floor(c.X);
int startH = (int)Math.Floor(c.Y);
int endH = (int)Math.Floor(a.Y);
for (int scan = startH; scan > endH; scan--)
{
double t = (scan - startH) / (endH - startH);
Vec2 left = Vec2.Lerp(uvc, uva, t);
Vec2 right = Vec2.Lerp(uvc, uvb, t);
Vec3 worldLeft = Vec3.Lerp(worldV3, worldV1, t);
Vec3 worldRight = Vec3.Lerp(worldV3, worldV2, t);
double zL = Lerp(c.Z, a.Z, t);
double zR = Lerp(c.Z, b.Z, t);
DrawLine(worldLeft, worldRight, new Vec3(leftX, scan, zL), new Vec3(rightX, scan, zR), left, right, img, ref shader, surface: true);
leftX -= invslope1;
rightX -= invslope2;
}
}
private void DrawLine(Vec3 worldV1, Vec3 worldV2, Vec3 v1, Vec3 v2, Vec2 uv1, Vec2 uv2, Material material, ref ShaderVariables shader, bool surface)
{
double dist2d = Math.Sqrt((v2.X - v1.X) * (v2.X - v1.X) + (v2.Y - v1.Y) * (v2.Y - v1.Y));
if (dist2d != 0)
{
double invdist = 1 / dist2d;
for (double i = 0; i < 1; i += invdist)
{
Vec3 world = Vec3.Lerp(worldV1, worldV2, i);
Vec3 pixel = Vec3.Lerp(v1, v2, i);
Vec2 uv = Vec2.Lerp(uv1, uv2, i);
shader.WorldPosition = world;
shader.ScreenPixel = pixel;
shader.UVCoordinates = uv;
var colour = surface ? material.Fragment(shader) : material.Edge(shader);
SetPixel(pixel, colour);
}
}
}
private void Rasterize(ref ShaderVariables shader, Triangle worldTri, Vec3 v1, Vec3 v2, Vec3 v3, Vec2 uv1, Vec2 uv2, Vec2 uv3, Material material)
{
// Sort vertices into ascending order of y
var worldV1 = worldTri.Item1;
var worldV2 = worldTri.Item2;
var worldV3 = worldTri.Item3;
if (v1.Y > v2.Y)
{
(v1, v2) = (v2, v1);
(uv1, uv2) = (uv2, uv1);
(worldV1, worldV2) = (worldV2, worldV1);
}
if (v2.Y > v3.Y)
{
(v2, v3) = (v3, v2);
(uv2, uv3) = (uv3, uv2);
(worldV2, worldV3) = (worldV3, worldV2);
}
if (v1.Y > v2.Y)
{
(v1, v2) = (v2, v1);
(uv1, uv2) = (uv2, uv1);
(worldV1, worldV2) = (worldV2, worldV1);
}
// Rasterize
if (v2.Y == v3.Y)
{
// Flat Bottom Triangle
DrawFlatBottomTriangle(worldV1, worldV2, worldV3, v1, v2, v3, uv1, uv2, uv3, material, ref shader);
DrawLine(worldV1, worldV2, v1, v2, uv1, uv2, material, ref shader, surface: false);
DrawLine(worldV2, worldV3, v2, v3, uv2, uv3, material, ref shader, surface: false);
DrawLine(worldV1, worldV3, v1, v3, uv1, uv3, material, ref shader, surface: false);
DrawVertex(worldV1, v1, uv1, material, ref shader);
DrawVertex(worldV2, v2, uv2, material, ref shader);
DrawVertex(worldV3, v3, uv3, material, ref shader);
}
else if (v1.Y == v2.Y)
{
// Flat Top Triangle
DrawFlatTopTriangle(worldV1, worldV2, worldV3, v1, v2, v3, uv1, uv2, uv3, material, ref shader);
DrawLine(worldV1, worldV2, v1, v2, uv1, uv2, material, ref shader, surface: false);
DrawLine(worldV2, worldV3, v2, v3, uv2, uv3, material, ref shader, surface: false);
DrawLine(worldV1, worldV3, v1, v3, uv1, uv3, material, ref shader, surface: false);
DrawVertex(worldV1, v1, uv1, material, ref shader);
DrawVertex(worldV2, v2, uv2, material, ref shader);
DrawVertex(worldV3, v3, uv3, material, ref shader);
}
else
{
// General Triangle
double t = (v2.Y - v3.Y) / (v1.Y - v3.Y);
Vec3 d = new Vec3(
(v1.X) + ((v2.Y - v1.Y) / (v3.Y - v1.Y)) * (v3.X - v1.X),
v2.Y,
Lerp(v3.Z, v1.Z, t)
);
Vec3 worldD = Vec3.Lerp(worldV3, worldV1, t);
Vec2 uvd = new Vec2(
Lerp(uv3.X, uv1.X, t),
Lerp(uv3.Y, uv1.Y, t)
);
DrawFlatBottomTriangle(worldV1, worldV2, worldD, v1, v2, d, uv1, uv2, uvd, material, ref shader);
DrawFlatTopTriangle(worldV2, worldD, worldV3, v2, d, v3, uv2, uvd, uv3, material, ref shader);
DrawLine(worldV1, worldV2, v1, v2, uv1, uv2, material, ref shader, surface: false);
DrawLine(worldV2, worldV3, v2, v3, uv2, uv3, material, ref shader, surface: false);
DrawLine(worldV1, worldV3, v1, v3, uv1, uv3, material, ref shader, surface: false);
DrawVertex(worldV1, v1, uv1, material, ref shader);
DrawVertex(worldV2, v2, uv2, material, ref shader);
DrawVertex(worldV3, v3, uv3, material, ref shader);
}
}
