Difference between revisions of "Barycentric coordinates"

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(use glm)
Line 5: Line 5:
 
// Compute barycentric coordinates (u, v, w) for
 
// Compute barycentric coordinates (u, v, w) for
 
// point p with respect to triangle (a, b, c)
 
// point p with respect to triangle (a, b, c)
void Barycentric(Point p, Point a, Point b, Point c, float &u, float &v, float &w)
+
glm::vec3 barycentric(glm::vec3 a, glm::vec3 b, glm::vec3 c, glm::vec3 p)
 
{
 
{
    Vector v0 = b - a, v1 = c - a, v2 = p - a;
+
        auto v0 = b - a;
    float d00 = Dot(v0, v0);
+
        auto v1 = c - a;
    float d01 = Dot(v0, v1);
+
        auto v2 = p - a;
    float d11 = Dot(v1, v1);
+
 
    float d20 = Dot(v2, v0);
+
        float d00 = glm::dot(v0, v0);
    float d21 = Dot(v2, v1);
+
        float d01 = glm::dot(v0, v1);
    float denom = d00 * d11 - d01 * d01;
+
        float d11 = glm::dot(v1, v1);
    v = (d11 * d20 - d01 * d21) / denom;
+
        float d20 = glm::dot(v2, v0);
    w = (d00 * d21 - d01 * d20) / denom;
+
        float d21 = glm::dot(v2, v1);
    u = 1.0f - v - w;
+
        float denom = d00 * d11 - d01 * d01;
 +
 
 +
        float v = (d11 * d20 - d01 * d21) / denom;
 +
        float w = (d00 * d21 - d01 * d20) / denom;
 +
        float u = 1.0f - v - w;
 +
 
 +
        return glm::vec3(u, v, w);
 
}
 
}
 
</source>
 
</source>
Line 24: Line 30:
 
<source lang="C++">
 
<source lang="C++">
 
// https://stackoverflow.com/a/11262425
 
// https://stackoverflow.com/a/11262425
Vector3d Tri::cartesian(const Vector3d& barycentric) const
+
glm::vec3 cartesian(glm::vec3 a, glm::vec3 b, glm::vec3 c, glm::vec3 p)  
 
{
 
{
      return barycentric.x * p0 + barycentric.y * p1 + barycentric.z * p2;
+
        return a * p.x + b * p.y + c * p.z;
 
}
 
}
 
</source>
 
</source>

Revision as of 13:43, 29 December 2019

Conversion from cartesian

// https://gamedev.stackexchange.com/a/23745
// Compute barycentric coordinates (u, v, w) for
// point p with respect to triangle (a, b, c)
glm::vec3 barycentric(glm::vec3 a, glm::vec3 b, glm::vec3 c, glm::vec3 p)
{
        auto v0 = b - a;
        auto v1 = c - a;
        auto v2 = p - a;

        float d00 = glm::dot(v0, v0);
        float d01 = glm::dot(v0, v1);
        float d11 = glm::dot(v1, v1);
        float d20 = glm::dot(v2, v0);
        float d21 = glm::dot(v2, v1);
        float denom = d00 * d11 - d01 * d01;

        float v = (d11 * d20 - d01 * d21) / denom;
        float w = (d00 * d21 - d01 * d20) / denom;
        float u = 1.0f - v - w;

        return glm::vec3(u, v, w);
}

Conversion to cartesian

// https://stackoverflow.com/a/11262425
glm::vec3 cartesian(glm::vec3 a, glm::vec3 b, glm::vec3 c, glm::vec3 p) 
{
        return a * p.x + b * p.y + c * p.z;
}