Added inverse square root optimisation

Author: sami-hatna66

external/Actor.cpp

@@ -11,35 +11,35 @@ Actor::Actor(vecType pPos, vecType pVelocity, vecType pDesiredVelocity, vecType
     color = pColor;
 }
 
-SYCL_EXTERNAL vecType Actor::getPos() {
+SYCL_EXTERNAL vecType Actor::getPos() const {
     return pos;
 }
 
-SYCL_EXTERNAL vecType Actor::getVelocity() {
+SYCL_EXTERNAL vecType Actor::getVelocity() const {
     return velocity;
 }
 
-SYCL_EXTERNAL vecType Actor::getDesiredVelocity() {
+SYCL_EXTERNAL vecType Actor::getDesiredVelocity() const {
     return desiredVelocity;
 }
 
-SYCL_EXTERNAL vecType Actor::getDestination() {
+SYCL_EXTERNAL vecType Actor::getDestination() const {
     return destination;
 }
 
-SYCL_EXTERNAL float Actor::getMass() {
+SYCL_EXTERNAL float Actor::getMass() const {
     return mass;
 }
 
-SYCL_EXTERNAL float Actor::getRadius() {
+SYCL_EXTERNAL float Actor::getRadius() const {
     return radius;
 }
 
-SYCL_EXTERNAL bool Actor::getAtDestination() {
+SYCL_EXTERNAL bool Actor::getAtDestination() const {
     return atDestination;
 }
 
-SYCL_EXTERNAL std::array<int, 3> Actor::getColor() {
+SYCL_EXTERNAL std::array<int, 3> Actor::getColor() const {
     return color;
 }
 

external/Actor.hpp

@@ -22,14 +22,14 @@ class Actor {
 public:    
     Actor(vecType pPos, vecType pVelocity, vecType pDesiredVelocity, vecType pDestination, float pMass, float pRadius, bool pAtDestination, std::array<int, 3> pColor);
 
-    SYCL_EXTERNAL vecType getPos();
-    SYCL_EXTERNAL vecType getVelocity();
-    SYCL_EXTERNAL vecType getDesiredVelocity();
-    SYCL_EXTERNAL vecType getDestination();
-    SYCL_EXTERNAL float getMass();
-    SYCL_EXTERNAL float getRadius();
-    SYCL_EXTERNAL bool getAtDestination();
-    SYCL_EXTERNAL std::array<int, 3> getColor();
+    SYCL_EXTERNAL vecType getPos() const;
+    SYCL_EXTERNAL vecType getVelocity() const;
+    SYCL_EXTERNAL vecType getDesiredVelocity() const;
+    SYCL_EXTERNAL vecType getDestination() const;
+    SYCL_EXTERNAL float getMass() const;
+    SYCL_EXTERNAL float getRadius() const;
+    SYCL_EXTERNAL bool getAtDestination() const;
+    SYCL_EXTERNAL std::array<int, 3> getColor() const;
 
     SYCL_EXTERNAL void setPos(vecType newPos);
     SYCL_EXTERNAL void setVelocity(vecType newVelocity);

external/DifferentialEq.cpp

@@ -54,8 +54,9 @@ SYCL_EXTERNAL void differentialEq(int z, sycl::accessor<Actor, 1, sycl::access::
     vecType newPos = i->getPos();
     vecType destination = i->getDestination();
 
-    if (newPos[0] <= destination[0] + 0.01 && newPos[0] >= destination[0] - 0.01
-        && pos[1] <= destination[1] + 0.01 && pos[1] >= destination[1] - 0.01) {
+    std::array<float, 4> destinationBoundingBox = {destination[0] + 0.01f, destination[0] - 0.01f, destination[1] + 0.01f, destination[1] - 0.01f};
+    if (newPos[0] <= destinationBoundingBox[0] && newPos[0] >= destinationBoundingBox[1]
+        && pos[1] <= destinationBoundingBox[2] && pos[1] >= destinationBoundingBox[3]) {
             i->setAtDestination(true);
         }
 }

external/MathHelper.cpp

@@ -4,18 +4,28 @@ SYCL_EXTERNAL vecType getDirectionVector(vecType from, vecType to) {
     return to - from;
 }
 
-SYCL_EXTERNAL vecType velFromSpeedAndDir(float s, vecType d) {
-    return d * (s / magnitude(d));
+SYCL_EXTERNAL vecType velFromSpeedAndDir(float speed, vecType direction) {
+    return direction * (speed * inverseMagnitude(direction));
 }
 
-SYCL_EXTERNAL vecType velToPoint(float s, vecType pos, vecType destination) {
-    return velFromSpeedAndDir(s, getDirectionVector(pos, destination));
+SYCL_EXTERNAL vecType velToPoint(float speed, vecType pos, vecType destination) {
+    return velFromSpeedAndDir(speed, getDirectionVector(pos, destination));
 }
 
 SYCL_EXTERNAL float magnitude(vecType inp) {
     return std::sqrt((inp[0] * inp[0]) + (inp[1] * inp[1]));
 }
 
+SYCL_EXTERNAL float inverseMagnitude(vecType inp) {
+    float x = (inp[0] * inp[0]) + (inp[1] * inp[1]);
+    float y = x;
+    uint32_t *i = reinterpret_cast<uint32_t *>(&y);
+    const uint32_t expMask = 0x7F800000;
+    const uint32_t magicNumber = 0x5F000000;
+    *i = magicNumber - ((*i >> 1) & expMask);
+    return (x * y * y + 1) / (2 * x * y);
+}
+
 SYCL_EXTERNAL float dotProduct(vecType a, vecType b) {
     return (a[0] * b[0]) + (a[1] * b[1]);
 }
@@ -25,7 +35,7 @@ SYCL_EXTERNAL float distance(vecType from, vecType to) {
 }
 
 SYCL_EXTERNAL vecType normalize(vecType inp) {
-    return inp / magnitude(inp);
+    return inp * inverseMagnitude(inp);
 }
 
 SYCL_EXTERNAL std::pair<float, vecType> getDistanceAndNiw(vecType point, std::array<vecType, 2> wall) {

external/MathHelper.hpp

@@ -10,12 +10,14 @@ using vecType = std::array<float, 2>;
 
 SYCL_EXTERNAL vecType getDirectionVector(vecType a, vecType b);
 
-SYCL_EXTERNAL vecType velFromSpeedAndDir(float s, vecType d);
+SYCL_EXTERNAL vecType velFromSpeedAndDir(float speed, vecType direction);
 
-SYCL_EXTERNAL vecType velToPoint(float s, vecType pos, vecType destination);
+SYCL_EXTERNAL vecType velToPoint(float speed, vecType pos, vecType destination);
 
 SYCL_EXTERNAL float magnitude(vecType inp);
 
+SYCL_EXTERNAL float inverseMagnitude(vecType inp);
+
 SYCL_EXTERNAL float dotProduct(vecType a, vecType b);
 
 SYCL_EXTERNAL float distance(vecType a, vecType b);

external/Room.cpp

@@ -4,6 +4,6 @@ Room::Room(std::vector<std::array<vecType, 2>> pWalls) {
     walls = pWalls;
 }
 
-std::vector<std::array<vecType, 2>> Room::getWalls() {
+std::vector<std::array<vecType, 2>> Room::getWalls() const {
     return walls;
 }

external/Room.hpp

@@ -14,7 +14,7 @@ class Room {
 public:    
     Room(std::vector<std::array<vecType, 2>> pWalls);
 
-    std::vector<std::array<vecType, 2>> getWalls();
+    std::vector<std::array<vecType, 2>> getWalls() const;
 };
 
 #endif

src/main.cpp

@@ -1,6 +1,7 @@
 #include <sycl/sycl.hpp>
 #include <SDL2/SDL.h>
 #include <iostream>
+#include <chrono>
 
 #include "Actor.hpp"
 #include "Room.hpp"