public Triangle (Mesh mesh, Vertex a, Vertex b, Vertex c)
{
this.a = a;
this.b = b;
this.c = c;
this.mesh = mesh;
}
// rasterization procedure
public static void ScanLine (int y, Vertex vertexLeftTop, Vertex vertexLeftBottom, Vertex vertexRightTop, Vertex vertexRightBottom, Texture texture)
{
// assumes a flat triangle
float gradientLeft = 1;
float gradientRight = 1;
// non flat triangle ?
if (vertexLeftTop.projected.y != vertexLeftBottom.projected.y) {
gradientLeft = (y - vertexLeftTop.projected.y) / (vertexLeftBottom.projected.y - vertexLeftTop.projected.y);
}
if (vertexRightTop.projected.y != vertexRightBottom.projected.y) {
gradientRight = (y - vertexRightTop.projected.y) / (vertexRightBottom.projected.y - vertexRightTop.projected.y);
}
// find x start position and end position using the y gradient
int left = (int)vertexLeftTop.projected.x.Interpolate (vertexLeftBottom.projected.x, gradientLeft);
int right = (int)vertexRightTop.projected.x.Interpolate (vertexRightBottom.projected.x, gradientRight);
// find the z start and value using the same interpolation
float zStart = vertexLeftTop.projected.z.Interpolate (vertexLeftBottom.projected.z, gradientLeft);
float zEnd = vertexRightTop.projected.z.Interpolate (vertexRightBottom.projected.z, gradientRight);
// get U start and end
float uStart = vertexLeftTop.uv.x.Interpolate (vertexLeftBottom.uv.x, gradientLeft);
float uEnd = vertexRightTop.uv.x.Interpolate (vertexRightBottom.uv.x, gradientRight);
// get V start and end
float vStart = vertexLeftTop.uv.y.Interpolate (vertexLeftBottom.uv.y, gradientLeft);
float vEnd = vertexRightTop.uv.y.Interpolate (vertexRightBottom.uv.y, gradientRight);
for (int x = left; x < right; x++) {
// while we do not need interpolation for horizontal pixels
// we need it for texturing and for getting correct z value
// zGradient name can be a bit misleading, as it will be used for UV's too
float zGradient = ((float)x - (float)left) / ((float)right - (float)left);
// get the z value using interpolation
float z = zStart.Interpolate (zEnd, zGradient);
// find texture uv coordinates using interpolation
// we can resue the zGradient
float u = uStart.Interpolate (uEnd, zGradient);
float v = vStart.Interpolate (vEnd, zGradient);
// get texture pixel color using UV system
// note the (1f - v), it is required as V coordinate is reversed (0 on bottom, 1 on top)
Vector3 color = texture.Map (u, 1f - v);
// write pixel on the device, de-normalizing colors
PutPixel (x, (int)y, z,
(byte)(color.x * 255),
(byte)(color.y * 255),
(byte)(color.z * 255));
}
}
public Mesh (string fileName, Texture texture)
{
this.position = Vector3.zero;
this.rotationEuler = Vector3.zero;
// initialize with default scaling
this.scale = new Vector3(1, 1, 1);
this.vertices = new List<Vector3> ();
this.uvs = new List<Vector2> ();
this.normals = new List<Vector3> ();
this.faces = new List<Triangle> ();
this.texture = texture;
using (StreamReader reader = new StreamReader (fileName)) {
while (true) {
string line = reader.ReadLine ();
if (line == null)
break;
// manage vertices
if (line.StartsWith ("v ")) {
string[] items = line.Split (' ');
// check for right handed and left handed !!!
this.vertices.Add (new Vector3 (
float.Parse (items [1], CultureInfo.InvariantCulture),
float.Parse (items [2], CultureInfo.InvariantCulture),
float.Parse (items [3], CultureInfo.InvariantCulture) * -1
));
}
// manage texture coordinates (uv)
if (line.StartsWith ("vt ")) {
string[] items = line.Split (' ');
this.uvs.Add (new Vector2 (
float.Parse (items [1], CultureInfo.InvariantCulture),
float.Parse (items [2], CultureInfo.InvariantCulture)
));
}
// manage normals
if (line.StartsWith ("vn ")) {
string[] items = line.Split (' ');
// check for right handed and left handed !!!
this.normals.Add (new Vector3 (
float.Parse (items [1], CultureInfo.InvariantCulture),
float.Parse (items [2], CultureInfo.InvariantCulture),
float.Parse (items [3], CultureInfo.InvariantCulture)
));
}
if (line.StartsWith ("f ")) {
string[] items = line.Split (' ');
string []id1 = items [1].Split ('/');
string []id2 = items [2].Split ('/');
string []id3 = items [3].Split ('/');
// vertex
Vector3 av = this.vertices [int.Parse(id1[0]) - 1];
Vector3 bv = this.vertices [int.Parse(id2[0]) - 1];
Vector3 cv = this.vertices [int.Parse(id3[0]) - 1];
// uv
Vector2 auv = this.uvs [int.Parse(id1[1]) - 1];
Vector2 buv = this.uvs [int.Parse(id2[1]) - 1];
Vector2 cuv = this.uvs [int.Parse(id3[1]) - 1];
// normal
Vector3 an = this.normals [int.Parse(id1[2]) - 1];
Vector3 bn = this.normals [int.Parse(id2[2]) - 1];
Vector3 cn = this.normals [int.Parse(id3[2]) - 1];
Vertex a = new Vertex (av, auv, an);
Vertex b = new Vertex (bv, buv, bn);
Vertex c = new Vertex (cv, cuv, cn);
this.faces.Add (new Triangle (this, a, b, c));
}
}
}
}
