minor optimizations in chunk

[blank.git] / src / geometry.cpp

diff --git a/src/geometry.cpp b/src/geometry.cpp
index 44217e981b49601c68be580eead0385efa6b45e2..416d930c4f68d0c24a0f690851264b98556b855b 100644 (file)
--- a/src/geometry.cpp
+++ b/src/geometry.cpp
@@ -11,122 +11,61 @@ bool Intersection(
        const glm::mat4 &M,
        float *dist,
        glm::vec3 *normal
-) {
+) noexcept {
        float t_min = 0.0f;
-       float t_max = 1.0e5f;
+       float t_max = std::numeric_limits<float>::infinity();
        const glm::vec3 aabb_pos(M[3].x, M[3].y, M[3].z);
        const glm::vec3 delta = aabb_pos - ray.orig;
 
        glm::vec3 t1(t_min, t_min, t_min), t2(t_max, t_max, t_max);
-       bool x_swap = false, y_swap = false, z_swap = false;
 
-       { // X
-               const glm::vec3 xaxis(M[0].x, M[0].y, M[0].z);
-               const float e = glm::dot(xaxis, delta);
-               const float f = glm::dot(ray.dir, xaxis);
+       for (int i = 0; i < 3; ++i) {
+               const glm::vec3 axis(M[i].x, M[i].y, M[i].z);
+               const float e = glm::dot(axis, delta);
+               const float f = glm::dot(axis, ray.dir);
 
                if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
-                       t1.x = (e + aabb.min.x) / f;
-                       t2.x = (e + aabb.max.x) / f;
+                       t1[i] = (e + aabb.min[i]) / f;
+                       t2[i] = (e + aabb.max[i]) / f;
 
-                       if (t1.x > t2.x) {
-                               std::swap(t1.x, t2.x);
-                               x_swap = true;
-                       }
-                       if (t1.x > t_min) {
-                               t_min = t1.x;
-                       }
-                       if (t2.x < t_max) {
-                               t_max = t2.x;
-                       }
-                       if (t_max < t_min) {
-                               return false;
-                       }
-               } else {
-                       if (aabb.min.x - e > 0.0f || aabb.max.x < 0.0f) {
-                               return false;
-                       }
-               }
-       }
-
-       { // Y
-               const glm::vec3 yaxis(M[1].x, M[1].y, M[1].z);
-               const float e = glm::dot(yaxis, delta);
-               const float f = glm::dot(ray.dir, yaxis);
+                       t_min = std::max(t_min, std::min(t1[i], t2[i]));
+                       t_max = std::min(t_max, std::max(t1[i], t2[i]));
 
-               if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
-                       t1.y = (e + aabb.min.y) / f;
-                       t2.y = (e + aabb.max.y) / f;
-
-                       if (t1.y > t2.y) {
-                               std::swap(t1.y, t2.y);
-                               y_swap = true;
-                       }
-                       if (t1.y > t_min) {
-                               t_min = t1.y;
-                       }
-                       if (t2.y < t_max) {
-                               t_max = t2.y;
-                       }
                        if (t_max < t_min) {
                                return false;
                        }
                } else {
-                       if (aabb.min.y - e > 0.0f || aabb.max.y < 0.0f) {
+                       if (aabb.min[i] - e < 0.0f || -aabb.max[i] - e > 0.0f) {
                                return false;
                        }
                }
        }
 
-       { // Z
-               const glm::vec3 zaxis(M[2].x, M[2].y, M[2].z);
-               const float e = glm::dot(zaxis, delta);
-               const float f = glm::dot(ray.dir, zaxis);
-
-               if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
-                       t1.z = (e + aabb.min.z) / f;
-                       t2.z = (e + aabb.max.z) / f;
-
-                       if (t1.z > t2.z) {
-                               std::swap(t1.z, t2.z);
-                               z_swap = true;
-                       }
-                       if (t1.z > t_min) {
-                               t_min = t1.z;
-                       }
-                       if (t2.z < t_max) {
-                               t_max = t2.z;
-                       }
-                       if (t_max < t_min) {
-                               return false;
-                       }
-               } else {
-                       if (aabb.min.z - e > 0.0f || aabb.max.z < 0.0f) {
-                               return false;
-                       }
-               }
-       }
+       glm::vec3 min_all(min(t1, t2));
 
        if (dist) {
                *dist = t_min;
        }
        if (normal) {
-               if (t1.x > t1.y) {
-                       if (t1.x > t1.z) {
-                               *normal = glm::vec3(x_swap ? 1 : -1, 0, 0);
+               glm::vec4 norm(0.0f);
+               if (min_all.x > min_all.y) {
+                       if (min_all.x > min_all.z) {
+                               norm.x = t2.x < t1.x ? 1 : -1;
                        } else {
-                               *normal = glm::vec3(0, 0, z_swap ? 1 : -1);
+                               norm.z = t2.z < t1.z ? 1 : -1;
                        }
-               } else if (t1.y > t1.z) {
-                       *normal = glm::vec3(0, y_swap ? 1 : -1, 0);
+               } else if (min_all.y > min_all.z) {
+                       norm.y = t2.y < t1.y ? 1 : -1;
                } else {
-                       *normal = glm::vec3(0, 0, z_swap ? 1 : -1);
+                       norm.z = t2.z < t1.z ? 1 : -1;
                }
+               norm = M * norm;
+               *normal = glm::vec3(norm);
        }
        return true;
 }
 
-bool CullTest(const AABB &box, const glm::mat4 &MVP) {
+bool CullTest(const AABB &box, const glm::mat4 &MVP) noexcept {
        // transform corners into clip space
        glm::vec4 corners[8] = {
                { box.min.x, box.min.y, box.min.z, 1.0f },