void DrawEntity(Entity entity)
{
Mesh mesh = entity.meshFilter.mesh;
Transform objectTransform = entity.transform;
Texture2D mainTex = entity.mainTex;
for (int i = 0; i < mesh.triangles.Length; i += 3)
{
int a_index = mesh.triangles[i];
int b_index = mesh.triangles[i + 1];
int c_index = mesh.triangles[i + 2];
TriangleAttribute <Color> colors = new TriangleAttribute <Color>(Color.red, Color.green, Color.blue);
TriangleAttribute <Vector2> uvs = new TriangleAttribute <Vector2>(mesh.uv[a_index], mesh.uv[b_index], mesh.uv[c_index]);
Vector4 a = V4Point(mesh.vertices[a_index]);
Vector4 b = V4Point(mesh.vertices[b_index]);
Vector4 c = V4Point(mesh.vertices[c_index]);
m_Transform m_objectTransform = new m_Transform();
m_objectTransform.CopyFromTransform(objectTransform);
a = m_objectTransform.TransformPoint(a);
b = m_objectTransform.TransformPoint(b);
c = m_objectTransform.TransformPoint(c);
TriangleAttribute <Vector3> pos_worlds = new TriangleAttribute <Vector3>(a, b, c);
TriangleAttribute <Vector3> normals =
new TriangleAttribute <Vector3>(
m_objectTransform.TransformDirection(mesh.normals[a_index]),
m_objectTransform.TransformDirection(mesh.normals[b_index]),
m_objectTransform.TransformDirection(mesh.normals[c_index]));
m_Transform cam_t = new m_Transform();
cam_t.CopyFromTransform(cam.transform);
a = cam_t.InverseTransformPoint(a);
b = cam_t.InverseTransformPoint(b);
c = cam_t.InverseTransformPoint(c);
Matrix4x4 p = GetProjectionMatrix(cam);
Matrix4x4 negetive = Matrix4x4.identity;
negetive.m22 = -1;
Matrix4x4 total = p * negetive;
a = ClipSpaceToScreenSpace(total * V4Point(a), pixelWidth, pixelHeight);
b = ClipSpaceToScreenSpace(total * V4Point(b), pixelWidth, pixelHeight);
c = ClipSpaceToScreenSpace(total * V4Point(c), pixelWidth, pixelHeight);
a.z = a.w;
b.z = b.w;
c.z = c.w;
Triangle3D triangle = new Triangle3D(a, b, c); //z值为摄像机空间z坐标
DrawTriangle(colorBuffer, triangle, colors, uvs, pos_worlds, normals, mainTex);
}
}
public void DrawTriangle(Texture2D colorBuffer, Triangle3D t, TriangleAttribute <Color> colors, TriangleAttribute <Vector2> uvs, TriangleAttribute <Vector3> pos_worlds, TriangleAttribute <Vector3> normals, Texture2D mainTex)
{
Vector2 min = Vector2.Min(Vector2.Min(t.a, t.b), t.c);
Vector2 max = Vector2.Max(Vector2.Max(t.a, t.b), t.c);
Vector2Int min_int = ClampInScreenSpace(pixelWidth, pixelHeight, Vector2Int.FloorToInt(min));
Vector2Int max_int = ClampInScreenSpace(pixelWidth, pixelHeight, Vector2Int.FloorToInt(max));
t.a.z = 1 / t.a.z;
t.b.z = 1 / t.b.z;
t.c.z = 1 / t.c.z;
colors.a *= t.a.z;
colors.b *= t.b.z;
colors.c *= t.c.z;
uvs.a *= t.a.z;
uvs.b *= t.b.z;
uvs.c *= t.c.z;
pos_worlds.a *= t.a.z;
pos_worlds.b *= t.b.z;
pos_worlds.c *= t.c.z;
normals.a *= t.a.z;
normals.b *= t.b.z;
normals.c *= t.c.z;
for (int y = min_int.y; y <= max_int.y; y++)
{
for (int x = min_int.x; x <= max_int.x; x++)
{
Vector2 p = new Vector2(x + 0.5f, y + 0.5f);
float ab = EdgeTest(t.a, t.b, p);
if (ab < 0)
{
continue;
}
float bc = EdgeTest(t.b, t.c, p);
if (bc < 0)
{
continue;
}
float ca = EdgeTest(t.c, t.a, p);
if (ca < 0)
{
continue;
}
float area = EdgeTest(t.a, t.b, t.c);
float w_a = bc / area;
float w_b = ca / area;
float w_c = ab / area;
float z = 1 / (w_a * t.a.z + w_b * t.b.z + w_c * t.c.z);
if (!DepthTest(x, y, z / cam.farClipPlane))
{
continue;
}
Color color = z * (colors.a * w_a + colors.b * w_b + colors.c * w_c);
Vector2 uv = z * (uvs.a * w_a + uvs.b * w_b + uvs.c * w_c);
Vector3 pos_world = z * (pos_worlds.a * w_a + pos_worlds.b * w_b + pos_worlds.c * w_c);
Vector3 normal = z * (normals.a * w_a + normals.b * w_b + normals.c * w_c);
Color col;
if (chekerBoard)
{
col = FragmentShader_ChckerBorad(uv, pos_world, normal, mainTex);
}
else
{
col = FragmentShader_BlinnPhong(uv, pos_world, normal, mainTex);
}
colorBuffer.SetPixel(x, y, col);
}
}
}
