figure out depth and normal in box/box test

diff --git a/src/model/geometry.cpp b/src/model/geometry.cpp
index b08d59fe5b556ebcdbc680b568cf36358f89a5f7..c2816b44a0f585f67781ef7e6bbe4e811dcd4fe9 100644 (file)
--- a/src/model/geometry.cpp
+++ b/src/model/geometry.cpp
@@ -70,7 +70,9 @@ bool Intersection(
        const AABB &a_box,
        const glm::mat4 &a_m,
        const AABB &b_box,
-       const glm::mat4 &b_m
+       const glm::mat4 &b_m,
+       float &depth,
+       glm::vec3 &normal
 ) noexcept {
        glm::vec3 a_corners[8] = {
                glm::vec3(a_m * glm::vec4(a_box.min.x, a_box.min.y, a_box.min.z, 1)),
@@ -103,6 +105,10 @@ bool Intersection(
                glm::vec3(b_m * glm::vec4(0, 0, 1, 0)),
        };
 
+       depth = std::numeric_limits<float>::infinity();
+       int min_axis = 0;
+
+       int cur_axis = 0;
        for (const glm::vec3 &axis : axes) {
                float a_min = std::numeric_limits<float>::infinity();
                float a_max = -std::numeric_limits<float>::infinity();
@@ -121,11 +127,17 @@ bool Intersection(
                }
 
                if (a_max < b_min || b_max < a_min) return false;
-       }
 
-       // TODO: find intersection point and normals
-       // normal could be deduced from the axis with the lowest min?
+               float overlap = std::min(a_max, b_max) - std::max(a_min, b_min);
+               if (overlap < depth) {
+                       depth = overlap;
+                       min_axis = cur_axis;
+               }
+
+               ++cur_axis;
+       }
 
+       normal = axes[min_axis];
        return true;
 }
 

diff --git a/src/model/geometry.hpp b/src/model/geometry.hpp
index f4498f5fa743ec734edc84aa90a87eb1d55757ab..df45fff2f2a2797d789b06b9bd2ad71feb3c6464 100644 (file)
--- a/src/model/geometry.hpp
+++ b/src/model/geometry.hpp
@@ -22,6 +22,10 @@ struct AABB {
                if (max.y < min.y) std::swap(max.y, min.y);
                if (max.z < min.z) std::swap(max.z, min.z);
        }
+
+       glm::vec3 Center() const noexcept {
+               return min + (max - min) * 0.5f;
+       }
 };
 
 struct Ray {
@@ -40,7 +44,9 @@ bool Intersection(
        const AABB &a_box,
        const glm::mat4 &a_m,
        const AABB &b_box,
-       const glm::mat4 &b_m) noexcept;
+       const glm::mat4 &b_m,
+       float &depth,
+       glm::vec3 &normal) noexcept;
 
 bool CullTest(const AABB &box, const glm::mat4 &MVP) noexcept;
 

diff --git a/src/model/shape.cpp b/src/model/shape.cpp
index 82659437f60fc87506f3847e181494514a99a7cd..8aa1c257e0d8f65eb69b54d588b4e763e30296bf 100644 (file)
--- a/src/model/shape.cpp
+++ b/src/model/shape.cpp
@@ -180,7 +180,9 @@ bool CuboidShape::Intersects(
        const AABB &box,
        const glm::mat4 &box_M
 ) const noexcept {
-       return Intersection(bb, M, box, box_M);
+       float depth;
+       glm::vec3 normal;
+       return Intersection(bb, M, box, box_M, depth, normal);
 }
 
 
@@ -347,7 +349,9 @@ bool StairShape::Intersects(
        const AABB &box,
        const glm::mat4 &box_M
 ) const noexcept {
-       return Intersection(bot, M, box, box_M) || Intersection(top, M, box, box_M);
+       float depth;
+       glm::vec3 normal;
+       return Intersection(bot, M, box, box_M, depth, normal) || Intersection(top, M, box, box_M, depth, normal);
 }
 
 }

diff --git a/src/world/World.cpp b/src/world/World.cpp
index 82701ce8686f48f20b3f24039a1239547375671f..4ab116c24f79f7f2f9581bdb67553204fd3dcc0f 100644 (file)
--- a/src/world/World.cpp
+++ b/src/world/World.cpp
@@ -178,6 +178,8 @@ bool World::Intersection(
 bool World::Intersection(const Entity &e) {
        AABB box = e.Bounds();
        glm::mat4 M = e.Transform(player->ChunkCoords());
+       // TODO: this only needs to check the chunks surrounding the entity's chunk position
+       //       need find out if that is quicker than the rough chunk bounds test
        for (Chunk &cur_chunk : chunks.Loaded()) {
                if (cur_chunk.Intersection(box, M, cur_chunk.Transform(player->ChunkCoords()))) {
                        return true;

diff --git a/src/world/chunk.cpp b/src/world/chunk.cpp
index 2216617ec52aac4dc59b317329d2103da84d872a..7591266be5433ecb6b7a0e6c200e1eb3026a68e7 100644 (file)
--- a/src/world/chunk.cpp
+++ b/src/world/chunk.cpp
@@ -5,6 +5,7 @@
 #include "Generator.hpp"
 
 #include <algorithm>
+#include <iostream>
 #include <limits>
 #include <queue>
 
@@ -486,7 +487,10 @@ bool Chunk::Intersection(
        const glm::mat4 &Mbox,
        const glm::mat4 &Mchunk
 ) const noexcept {
-       if (!blank::Intersection(box, Mbox, Bounds(), Mchunk)) {
+       float penetration;
+       glm::vec3 normal;
+
+       if (!blank::Intersection(box, Mbox, Bounds(), Mchunk, penetration, normal)) {
                return false;
        }
        for (int idx = 0, z = 0; z < depth; ++z) {

diff --git a/tst/model/GeometryTest.cpp b/tst/model/GeometryTest.cpp
index 71830c6176930f31421e31af7afb052dff937292..82f88eeefcf5de296a3aaf9e013d65cd97509dde 100644 (file)
--- a/tst/model/GeometryTest.cpp
+++ b/tst/model/GeometryTest.cpp
@@ -64,6 +64,10 @@ void GeometryTest::testRayBoxIntersection() {
 }
 
 void GeometryTest::testBoxBoxIntersection() {
+       const float delta = std::numeric_limits<float>::epsilon();
+       float depth = 0;
+       glm::vec3 normal(0);
+
        AABB box{ { -1, -1, -1 }, { 1, 1, 1 } }; // 2x2x2 cube centered around origin
        glm::mat4 Ma(1); // identity
        glm::mat4 Mb(1); // identity
@@ -71,28 +75,43 @@ void GeometryTest::testBoxBoxIntersection() {
 
        CPPUNIT_ASSERT_MESSAGE(
                "identical OBBs don't intersect",
-               Intersection(box, Ma, box, Mb)
+               Intersection(box, Ma, box, Mb, depth, normal)
+       );
+       // depth is two, but normal can be any
+       // (will probably be the first axis of box a, but any is valid)
+       CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+               "penetration depth of coincidental 2x2x2 boxes is not 2",
+               2.0f, depth, delta
        );
 
        Ma = glm::translate(glm::vec3(-2, 0, 0)); // 2 to the left
        Mb = glm::translate(glm::vec3(2, 0, 0)); // 2 to the right
        CPPUNIT_ASSERT_MESSAGE(
                "distant OBBs intersect (2 apart, no rotation)",
-               !Intersection(box, Ma, box, Mb)
+               !Intersection(box, Ma, box, Mb, depth, normal)
        );
+       // depth and normal undefined for non-intersecting objects
 
        Ma = glm::rotate(PI_0p25, glm::vec3(0, 0, 1)); // rotated 45° around Z
        Mb = glm::translate(glm::vec3(2.4, 0, 0)); // 2.4 to the right
-       // they should barely touch. intersect by about 0.01 if my head works
+       // they should barely touch. intersect by about sqrt(2) - 1.4 if my head works
        CPPUNIT_ASSERT_MESSAGE(
                "OBBs don't intersect (one rotated by 45°)",
-               Intersection(box, Ma, box, Mb)
+               Intersection(box, Ma, box, Mb, depth, normal)
+       );
+       CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE(
+               "bad penetration depth (with rotation)",
+               0.01421356237309504880f, depth, delta
+       );
+       CPPUNIT_ASSERT_EQUAL_MESSAGE(
+               "bad intersection normal (with rotation)",
+               glm::vec3(1, 0, 0), abs(normal) // normal can be in + or - x, therefore abs()
        );
 
        Mb = glm::translate(glm::vec3(3, 0, 0)); // 3 to the right
        CPPUNIT_ASSERT_MESSAGE(
                "OBBs intersect (one rotated by 45°)",
-               !Intersection(box, Ma, box, Mb)
+               !Intersection(box, Ma, box, Mb, depth, normal)
        );
 }