From 695e3db5f9b24ad46d236a28f9896dc9e5a619f6 Mon Sep 17 00:00:00 2001
From: LaG1924 <12997935+LaG1924@users.noreply.github.com>
Date: Tue, 6 Feb 2018 16:47:21 +0500
Subject: Simplified raycast

---
 src/GameState.cpp |  4 ++-
 src/World.cpp     | 93 +++++++++----------------------------------------------
 src/World.hpp     |  8 ++++-
 3 files changed, 25 insertions(+), 80 deletions(-)

diff --git a/src/GameState.cpp b/src/GameState.cpp
index 650cd6f..180db98 100644
--- a/src/GameState.cpp
+++ b/src/GameState.cpp
@@ -36,7 +36,9 @@ void GameState::Update(float deltaTime) {
         direction.y = sin(glm::radians(playerPitch));
         direction.z = sin(glm::radians(playerYaw)) * cos(glm::radians(playerPitch));
 
-        selectedBlock = world.Raycast(player->pos + player->EyeOffset, direction, distanceToSelectedBlock);
+        RaycastResult raycast = world.Raycast(player->pos + player->EyeOffset, direction);
+        selectedBlock = raycast.isHit ? raycast.hitBlock : Vector(0,0,0);
+        distanceToSelectedBlock = raycast.isHit ? (player->pos - raycast.hitPos).GetLength() : 0.0f;
 	}
 }
 
diff --git a/src/World.cpp b/src/World.cpp
index e4c2a1b..4678964 100644
--- a/src/World.cpp
+++ b/src/World.cpp
@@ -135,86 +135,23 @@ const Section &World::GetSection(Vector sectionPos) {
     }
 }
 
-Vector World::Raycast(glm::vec3 position, glm::vec3 direction, float &distance) {
-    auto triangle_intersection = [&] (const glm::vec3 &v0, const glm::vec3 &v1, const glm::vec3 &v2) -> bool {
-        glm::vec3 e1 = v1 - v0;
-        glm::vec3 e2 = v2 - v0;
-
-        glm::vec3 pvec = glm::cross(direction, e2);
-
-        float det = glm::dot(e1, pvec);
-        if (det < 1e-8 && det > -1e-8) {
-            return 0;
-        }
-
-        float inv_det = 1 / det;
-        glm::vec3 tvec = position - v0;
-        float u = dot(tvec, pvec) * inv_det;
-        if (u < 0 || u > 1) {
-            return 0;
-        }
-
-        glm::vec3 qvec = cross(tvec, e1);
-        float v = dot(direction, qvec) * inv_det;
-        if (v < 0 || u + v > 1) {
-            return 0;
-        }
-        return dot(e2, qvec) * inv_det;
-    };
-
-    float minDistance = 1000000;
-    Vector minBlock;
-
-    for (int y = position.y-5; y<position.y+5;y++) {
-        for (int z = position.z-5;z<position.z+5;z++) {
-            for (int x = position.x-5;x<position.x+5;x++) {
-                if (GetBlockId(Vector(x,y,z)) == BlockId{0,0})
-                    continue;
-
-                //Z- north
-                //Z+ south
-                //X+ east
-                //X- west
-                //Y+ top
-                //Y- bottom
-                glm::vec3 vNNN {x,y,z};
-                glm::vec3 vNNP {x,y,z+1};
-                glm::vec3 vNPN {x,y+1,z};
-                glm::vec3 vNPP {x,y+1,z+1};
-                glm::vec3 vPNN {x+1,y,z};
-                glm::vec3 vPNP {x+1,y,z+1};
-                glm::vec3 vPPN {x+1,y+1,z};
-                glm::vec3 vPPP {x+1,y+1,z+1};
-
-                float west = triangle_intersection(vNNN,vNPN,vNPP);
-                float east = triangle_intersection(vPPN,vPNP,vPNN);
-                float north = triangle_intersection(vNPN,vPNN,vNNN);
-                float south = triangle_intersection(vNNP,vNPP,vPNP);
-                float top = triangle_intersection(vNPN,vNPP,vPPN);
-                float bottom = triangle_intersection(vNNN,vNNP,vPNN);
-
-                if (west || east || north || south || top || bottom) {
-                    float len = (Vector(position.x,position.y,position.z) - Vector(x,y,z)).GetLength();
-                    if (len <= minDistance) {
-                        float we = west < east && west != 0 ? west : east;
-                        float ns = north < south && north != 0 ? north : south;
-                        float tb = top < bottom && top != 0 ? top : bottom;
-                        float wens = we < ns && we != 0 ? we : ns;
-                        minDistance = wens < tb && wens != 0? wens : tb;
-                        minBlock = Vector(x,y,z);
-                    }
-                }
-            }
-        }
-    }
-
-    if (minDistance == 1000000) {
-        distance = 0;
-        return Vector(0,0,0);
+RaycastResult World::Raycast(glm::vec3 position, glm::vec3 direction) {
+    const float maxLen = 5.0;
+    const float step = 0.01;
+    glm::vec3 pos;
+    float len=0;
+    Vector blockPos = Vector(position.x,position.y,position.z);
+    while (GetBlockId(blockPos) == BlockId{0, 0} && len <= maxLen) {
+        pos = position + direction * len;
+        len += step;
+        blockPos = Vector(floor(pos.x),floor(pos.y),floor(pos.z));
     }
 
-    distance = minDistance;
-    return minBlock;
+    RaycastResult result;
+    result.isHit = !(GetBlockId(blockPos) == BlockId{0, 0});
+    result.hitPos = VectorF(pos.x,pos.y,pos.z);
+    result.hitBlock = blockPos;
+    return result;
 }
 
 void World::UpdatePhysics(float delta)
diff --git a/src/World.hpp b/src/World.hpp
index 50dfa31..2c80b31 100644
--- a/src/World.hpp
+++ b/src/World.hpp
@@ -19,6 +19,12 @@ class PacketMultiBlockChange;
 class PacketUnloadChunk;
 class StreamInput;
 
+struct RaycastResult {
+    bool isHit;
+    Vector hitBlock;
+    VectorF hitPos;
+};
+
 class World {
     int dimension = 0;
 
@@ -55,7 +61,7 @@ public:
 
     const Section &GetSection(Vector sectionPos);
 
-    Vector Raycast(glm::vec3 position, glm::vec3 direction, float &distance);
+    RaycastResult Raycast(glm::vec3 position, glm::vec3 direction);
 
     void UpdatePhysics(float delta);
 
-- 
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