move human I/O related stuff into separate file

[blank.git] / src / geometry.cpp

diff --git a/src/geometry.cpp b/src/geometry.cpp
index c5f806997fae8cee4d9e26311ec0067dd607e808..44217e981b49601c68be580eead0385efa6b45e2 100644 (file)
--- a/src/geometry.cpp
+++ b/src/geometry.cpp
@@ -1,31 +1,43 @@
 #include "geometry.hpp"
 
+#include <limits>
+
 
 namespace blank {
 
-bool Intersection(const Ray &ray, const AABB &aabb, const glm::mat4 &M, float *dist) {
+bool Intersection(
+       const Ray &ray,
+       const AABB &aabb,
+       const glm::mat4 &M,
+       float *dist,
+       glm::vec3 *normal
+) {
        float t_min = 0.0f;
        float t_max = 1.0e5f;
        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);
 
-               if (std::abs(f) > 0.001f) {
-                       float t1 = (e + aabb.min.x) / f;
-                       float t2 = (e + aabb.max.x) / f;
+               if (std::abs(f) > std::numeric_limits<float>::epsilon()) {
+                       t1.x = (e + aabb.min.x) / f;
+                       t2.x = (e + aabb.max.x) / f;
 
-                       if (t1 > t2) {
-                               std::swap(t1, t2);
+                       if (t1.x > t2.x) {
+                               std::swap(t1.x, t2.x);
+                               x_swap = true;
                        }
-                       if (t1 > t_min) {
-                               t_min = t1;
+                       if (t1.x > t_min) {
+                               t_min = t1.x;
                        }
-                       if (t2 < t_max) {
-                               t_max = t2;
+                       if (t2.x < t_max) {
+                               t_max = t2.x;
                        }
                        if (t_max < t_min) {
                                return false;
@@ -42,18 +54,19 @@ bool Intersection(const Ray &ray, const AABB &aabb, const glm::mat4 &M, float *d
                const float e = glm::dot(yaxis, delta);
                const float f = glm::dot(ray.dir, yaxis);
 
-               if (std::abs(f) > 0.001f) {
-                       float t1 = (e + aabb.min.y) / f;
-                       float t2 = (e + aabb.max.y) / f;
+               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 > t2) {
-                               std::swap(t1, t2);
+                       if (t1.y > t2.y) {
+                               std::swap(t1.y, t2.y);
+                               y_swap = true;
                        }
-                       if (t1 > t_min) {
-                               t_min = t1;
+                       if (t1.y > t_min) {
+                               t_min = t1.y;
                        }
-                       if (t2 < t_max) {
-                               t_max = t2;
+                       if (t2.y < t_max) {
+                               t_max = t2.y;
                        }
                        if (t_max < t_min) {
                                return false;
@@ -70,18 +83,19 @@ bool Intersection(const Ray &ray, const AABB &aabb, const glm::mat4 &M, float *d
                const float e = glm::dot(zaxis, delta);
                const float f = glm::dot(ray.dir, zaxis);
 
-               if (std::abs(f) > 0.001f) {
-                       float t1 = (e + aabb.min.z) / f;
-                       float t2 = (e + aabb.max.z) / f;
+               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 > t2) {
-                               std::swap(t1, t2);
+                       if (t1.z > t2.z) {
+                               std::swap(t1.z, t2.z);
+                               z_swap = true;
                        }
-                       if (t1 > t_min) {
-                               t_min = t1;
+                       if (t1.z > t_min) {
+                               t_min = t1.z;
                        }
-                       if (t2 < t_max) {
-                               t_max = t2;
+                       if (t2.z < t_max) {
+                               t_max = t2.z;
                        }
                        if (t_max < t_min) {
                                return false;
@@ -96,7 +110,58 @@ bool Intersection(const Ray &ray, const AABB &aabb, const glm::mat4 &M, float *d
        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);
+                       } else {
+                               *normal = glm::vec3(0, 0, z_swap ? 1 : -1);
+                       }
+               } else if (t1.y > t1.z) {
+                       *normal = glm::vec3(0, y_swap ? 1 : -1, 0);
+               } else {
+                       *normal = glm::vec3(0, 0, z_swap ? 1 : -1);
+               }
+       }
        return true;
 }
 
+bool CullTest(const AABB &box, const glm::mat4 &MVP) {
+       // transform corners into clip space
+       glm::vec4 corners[8] = {
+               { box.min.x, box.min.y, box.min.z, 1.0f },
+               { box.min.x, box.min.y, box.max.z, 1.0f },
+               { box.min.x, box.max.y, box.min.z, 1.0f },
+               { box.min.x, box.max.y, box.max.z, 1.0f },
+               { box.max.x, box.min.y, box.min.z, 1.0f },
+               { box.max.x, box.min.y, box.max.z, 1.0f },
+               { box.max.x, box.max.y, box.min.z, 1.0f },
+               { box.max.x, box.max.y, box.max.z, 1.0f },
+       };
+       for (glm::vec4 &corner : corners) {
+               corner = MVP * corner;
+               corner /= corner.w;
+       }
+
+       int hits[6] = { 0, 0, 0, 0, 0, 0 };
+
+       // check how many corners lie outside
+       for (const glm::vec4 &corner : corners) {
+               if (corner.x >  1.0f) ++hits[0];
+               if (corner.x < -1.0f) ++hits[1];
+               if (corner.y >  1.0f) ++hits[2];
+               if (corner.y < -1.0f) ++hits[3];
+               if (corner.z >  1.0f) ++hits[4];
+               if (corner.z < -1.0f) ++hits[5];
+       }
+
+       // if all corners are outside any given clip plane, the test is true
+       for (int hit : hits) {
+               if (hit == 8) return true;
+       }
+
+       // otherwise the box might still get culled completely, but can't say for sure ;)
+       return false;
+}
+
 }