public void Render(World world, Camera camera, DirectBitmap screen)
{
Vector3f light = new Vector3f(0, 1, 0);
light.MultiplySelf(1 / light.Length);
// Матрица вида = матрице перемещения камеры
var viewMatrix = camera.TranslationMatrix.Inverse();
// матрица проекции
var projectionMatrix = camera.ProjectionMatrix;
foreach (var mesh in world.Meshes)
{
var random = new Random(0);
foreach (var triangle in mesh.Triangles)
{
// Duplicate triangle to not accidentally corrupt any data
triangle.Duplicate(_tri);
#region Calculate Triangle To Camera Ray
bool preciseCameraRay = false;
if (preciseCameraRay)
{
var triWorldCenterX = (_tri[0].X + _tri[1].X + _tri[2].X) / 3f;
var triWorldCenterY = (_tri[0].Y + _tri[1].Y + _tri[2].Y) / 3f;
var triWorldCenterZ = (_tri[0].Z + _tri[1].Z + _tri[2].Z) / 3f;
_cameraRay.X = camera.Position.X - triWorldCenterX;
_cameraRay.Y = camera.Position.Y - triWorldCenterY;
_cameraRay.Z = camera.Position.Z - triWorldCenterZ;
}
else
{
_cameraRay.X = camera.Position.X - _tri[0].X;
_cameraRay.Y = camera.Position.Y - _tri[0].Y;
_cameraRay.Z = camera.Position.Z - _tri[0].Z;
}
#endregion
#region Calculate Triangle Normal
// CounterClockWise Model
// https://stackoverflow.com/questions/22171776/order-of-vector-cross-product-for-a-ccw-triangle
var normal = SomeMaths.Cross(_tri[0], _tri[1], _tri[2]);
normal.MultiplySelf(1 / normal.Length); // normalize
#endregion
#region Clip Invisible Triangles
if (normal.Dot(_cameraRay) < 0)
{
// clip invisible triangles
continue;
}
#endregion
#region Calculate Model Matrix
// !!! IMPORTANT http://opengl-tutorial.blogspot.com/p/3.html
// Сначала нужно изменить размер, потом прокрутить и лишь потом сдвинуть.
modelMatrix.MakeIdentity();
modelMatrix.MultiplySelf(mesh.ScaleMatrix);
modelMatrix.MultiplySelf(mesh.RotationMatrix);
modelMatrix.MultiplySelf(mesh.TranslationMatrix);
#endregion
#region Project From 3D To 2D
// проецируем точки треугольника по правилу MVP (model view project)
for (int i = 0; i < 3; i++)
{
_tri[i].MultiplySelf(modelMatrix);
_tri[i].MultiplySelf(viewMatrix);
_tri[i].MultiplySelf(projectionMatrix);
}
#endregion
#region Translate To Screen Center
// Сдвигаем точки в центр экрана
for (int i = 0; i < 3; i++)
{
_tri[i].X += 1.0f;
_tri[i].Y += 1.0f;
_tri[i].X *= screen.Width / 2f;
_tri[i].Y *= screen.Height / 2f;
}
#endregion
#region Calculate Light Alignment
float lightAlignment = light.Dot(normal);
#endregion
#region Calculate Color
uint luminance = (uint)(Math.Max(0.3f, Math.Min(lightAlignment, 0.95f)) * 0xFF) & 0xFF;
uint color = 0xFFu << 24 | luminance << 16 | luminance << 8 | luminance;
// int color = 0xFF << 24 | random.Next(0, 255) << 16 | random.Next(0, 255) << 8 | random.Next(0, 255);
#endregion
#region Fill Solid
// SOLID
SomeDrawing.FillTriangle(screen, _tri[0], _tri[1], _tri[2], color);
#endregion
#region Draw Wireframe
// WIREFRAME
for (int i = 0; i < 3; i++)
{
SomeDrawing.Line(screen, _tri[i], _tri[(i + 1) % 3], 0xFFFFFFFF);
}
#endregion
#region Calculate Screen Space Triangle Center
var triScreenCenterX = (_tri[0].X + _tri[1].X + _tri[2].X) / 3f;
var triScreenCenterY = (_tri[0].Y + _tri[1].Y + _tri[2].Y) / 3f;
var triScreenCenterZ = (_tri[0].Z + _tri[1].Z + _tri[2].Z) / 3f;
#endregion
#region Draw Vertex To Center Line
// VERTEX TO CENTER
for (int i = 0; i < 3; i++)
{
SomeDrawing.Line(screen, _tri[i].X, _tri[i].Y, triScreenCenterX, triScreenCenterY, 0xFFFF0000);
}
#endregion
#region Draw Normal
float normalLength = 40;
// NORMAL
SomeDrawing.Line(screen, triScreenCenterX, triScreenCenterY,
triScreenCenterX + normal.X * normalLength,
triScreenCenterY + normal.Y * normalLength,
0xFF0000FF);
#endregion
}
}
}