feat: barycentric interpolation for normals

polygon.hpp

@@ -7,8 +7,10 @@ struct polygon {
     vec3 points[3];
     decimal delta[9];
     bool small = false;
+    decimal baryFactor;
 
     decimal bounding[4]; // min x, max x, min y, max y
+    vec3 normals[3];
 
     polygon(const vec3 &v1, const vec3 &v2, const vec3 &v3)
         : points{v1, v2, v3}, delta{} {}
@@ -40,6 +42,16 @@ struct polygon {
             if (bounding[3] < points[i].y())
                 bounding[3] = points[i].y();
         }
+
+        baryFactor =
+            (points[1].x() - points[0].x()) * (points[2].y() - points[1].y()) -
+            (points[1].y() - points[0].y()) * (points[2].x() - points[1].x());
+
+        if (baryFactor.isSmall()) {
+            small = true;
+        } else
+            baryFactor = decimal(1.0) / baryFactor;
+        // std::cout << baryFactor << std::endl;
         /*if ((bounding[1].i - bounding[0].i < 1 << HALF_SHIFT) &&
             (bounding[3].i - bounding[2].i < 1 << HALF_SHIFT))
             small = true;*/
@@ -53,7 +65,7 @@ struct polygon {
                 return true;
             vec3 d = p;
             if ((d.x() * delta[i * 3] + d.y() * delta[i * 3 + 1] +
-                 delta[i * 3 + 2]) > decimal(0))
+                 delta[i * 3 + 2]) > decimal(0.2))
                 return false;
         }
         return true;
@@ -64,6 +76,32 @@ struct polygon {
         }
         return os;
     }
+
+    vec3 calcNormal(vec3 barycentrics) {
+        vec3 result = normals[0] * barycentrics[0] +
+                      normals[1] * barycentrics[1] +
+                      normals[2] * barycentrics[2];
+        return result.normalize();
+    }
+
+    decimal calcDepth(vec3 barycentrics) {
+        return points[0].z() * barycentrics[0] +
+               points[1].z() * barycentrics[1] +
+               points[2].z() * barycentrics[2];
+    }
+
+    vec3 calcBarycentric(vec3 s) {
+        if (small)
+            return vec3(decimal(0.333), decimal(0.333), decimal(0.333));
+        vec3 result;
+        result[0] = (points[1].x() - s.x()) * (points[2].y() - s.y()) -
+                    (points[2].x() - s.x()) * (points[1].y() - s.y());
+        result[1] = (points[2].x() - s.x()) * (points[0].y() - s.y()) -
+                    (points[0].x() - s.x()) * (points[2].y() - s.y());
+        result = result * baryFactor;
+        result[2] = decimal(1.0) - result[1] - result[0];
+        return result;
+    }
 };
 
 #endif