120 lines
5 KiB
C++
120 lines
5 KiB
C++
#include "primitive/triangle.h"
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#include <algorithm>
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// Constructor /////////////////////////////////////////////////////////////////
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Triangle::Triangle(std::shared_ptr<Shader> const &shader) : Primitive(shader) {}
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Triangle::Triangle(Vector3d const &a, Vector3d const &b, Vector3d const &c, std::shared_ptr<Shader> const &shader) : Primitive(shader), vertex{a, b, c} {}
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Triangle::Triangle(Vector3d const &a, Vector3d const &b, Vector3d const &c, Vector3d const &na, Vector3d const &nb, Vector3d const &nc, std::shared_ptr<Shader> const &shader) : Primitive(shader), vertex{a, b, c}, normal{na, nb, nc} {}
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Triangle::Triangle(Vector3d const &a, Vector3d const &b, Vector3d const &c, Vector3d const &na, Vector3d const &nb, Vector3d const &nc, Vector2d const &ta, Vector2d const &tb, Vector2d const &tc, std::shared_ptr<Shader> const &shader)
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: Primitive(shader), vertex{a, b, c}, normal{na, nb, nc}, surface{ta, tb, tc} {}
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Triangle::Triangle(Vector3d const &a, Vector3d const &b, Vector3d const &c, Vector3d const &na, Vector3d const &nb, Vector3d const &nc, Vector3d const &tana, Vector3d const &tanb, Vector3d const &tanc, Vector3d const &ba,
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Vector3d const &bb, Vector3d const &bc, Vector2d const &ta, Vector2d const &tb, Vector2d const &tc, std::shared_ptr<Shader> const &shader)
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: Primitive(shader), vertex{a, b, c}, normal{na, nb, nc}, tangent{tana, tanb, tanc}, bitangent{ba, bb, bc}, surface{ta, tb, tc} {}
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// Primitive functions /////////////////////////////////////////////////////////
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bool Triangle::intersectArea(Ray &ray) const {
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// alternative triangle test
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// "signed" triangle area with respect to triangle normal
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auto triangleArea = [](Vector3d const &v0, Vector3d const &v1, Vector3d const &v2, Vector3d const &normal = Vector3d(0, 0, 0)) {
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if (length(normal) < EPSILON) {
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return length(crossProduct(v2 - v0, v1 - v0)) / 2.0f;
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} else {
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Vector3d const cp = crossProduct(v2 - v0, v1 - v0);
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return dotProduct(cp, normal) > 0.0f ? length(cp) / 2.0f : -length(cp) / 2.0f;
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}
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};
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// begin ray-plane intersection ----------------------------
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Vector3d normal = normalized(crossProduct(vertex[2] - vertex[0], vertex[1] - vertex[0]));
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float const cosine = dotProduct(ray.direction, normal);
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if (abs(cosine) < EPSILON)
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return false;
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float const t = dotProduct(vertex[0] - ray.origin, normal) / cosine;
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if (t < EPSILON || ray.length < t)
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return false;
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Vector3d const p = ray.origin + t * ray.direction;
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// end ray-plane intersection ----------------------------
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float const fullArea = triangleArea(vertex[0], vertex[1], vertex[2]);
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float const a = triangleArea(p, vertex[0], vertex[1], normal) / fullArea;
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float const b = triangleArea(p, vertex[2], vertex[0], normal) / fullArea;
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if ((a < 0.0f) || (a > 1.0f) || (b < 0.0f) || (a + b > 1.0f))
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return false;
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// Set the surface position (barycentric coordinates) and tangent Vector
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ray.surface = a * this->surface[1] + b * this->surface[2] + (1 - a - b) * this->surface[0];
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// Set the new length and the current primitive
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ray.length = t;
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ray.primitive = this;
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// True, because the primitive was hit
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return true;
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}
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bool Triangle::intersect(Ray &ray) const {
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// We use the Möller–Trumbore intersection algorithm
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// Determine two neighboring edge vectors
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Vector3d const edge1 = this->vertex[1] - this->vertex[0];
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Vector3d const edge2 = this->vertex[2] - this->vertex[0];
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// Begin calculating determinant
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Vector3d const pVec = crossProduct(ray.direction, edge2);
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// Make sure the ray is not parallel to the triangle
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float const det = dotProduct(edge1, pVec);
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if (fabs(det) < EPSILON)
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return false;
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float const inv_det = 1.0f / det;
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// Calculate u and test bound
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Vector3d const tVec = ray.origin - this->vertex[0];
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float const u = dotProduct(tVec, pVec) * inv_det;
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// Test whether the intersection lies outside the triangle
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if (0.0f > u || u > 1.0f)
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return false;
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// Calculate v and test bound
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Vector3d const qVec = crossProduct(tVec, edge1);
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float const v = dotProduct(ray.direction, qVec) * inv_det;
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// Test whether the intersection lies outside the triangle
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if (0.0f > v || u + v > 1.0f)
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return false;
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// Test whether this is the foremost primitive in front of the camera
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float const t = dotProduct(edge2, qVec) * inv_det;
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if (t < EPSILON || ray.length < t)
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return false;
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// Calculate the normal
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// IMPLEMENT ME
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// Calculate the surface position
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ray.surface = u * this->surface[1] + v * this->surface[2] + (1 - u - v) * this->surface[0];
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// Set the new length and the current primitive
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ray.length = t;
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ray.primitive = this;
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// True, because the primitive was hit
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return true;
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}
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// Bounding box ////////////////////////////////////////////////////////////////
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float Triangle::minimumBounds(int dimension) const { return std::min(this->vertex[0][dimension], std::min(this->vertex[1][dimension], this->vertex[2][dimension])); }
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float Triangle::maximumBounds(int dimension) const { return std::max(this->vertex[0][dimension], std::max(this->vertex[1][dimension], this->vertex[2][dimension])); }
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