quadtree experiment

quadtree/main.c

@@ -0,0 +1,122 @@
+#include <raylib.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+typedef struct Node {
+    Rectangle bounds;
+    Vector2 entities[4];
+    int entity_count;
+    struct Node* children[4];
+} Node;
+
+Node* create_node(Rectangle bounds) {
+    Node* n = calloc(1, sizeof(Node));
+    n->bounds = bounds;
+    return n;
+}
+
+void split_node(Node* n) {
+    Rectangle b = n->bounds;
+    Vector2 half = (Vector2){ b.width / 2.0f, b.height / 2.0f };
+    n->children[0] = create_node((Rectangle){ b.x, b.y, half.x, half.y });
+    n->children[1] = create_node((Rectangle){ b.x + half.x, b.y, half.x, half.y });
+    n->children[2] = create_node((Rectangle){ b.x, b.y + half.y, half.x, half.y });
+    n->children[3] = create_node((Rectangle){ b.x + half.x, b.y + half.y, half.x, half.y });
+}
+
+int inside(Node* n, Vector2 p) {
+    return p.x > n->bounds.x && p.x < n->bounds.x + n->bounds.width &&
+            p.y > n->bounds.y && p.y < n->bounds.y + n->bounds.height;
+}
+
+int is_leaf(Node* n) {
+    return 
+        n->children[0] == NULL &&
+        n->children[1] == NULL &&
+        n->children[2] == NULL &&
+        n->children[3] == NULL;
+}
+
+void add(Node* n, Vector2 p) {
+    if(n->entity_count >= 4) {
+        if(is_leaf(n)) {
+            split_node(n);
+        }
+
+        int added = 0;
+        
+        for(int i = 0; i < 4; i++) {
+            if(inside(n->children[i], p)) {
+                add(n->children[i], p);
+                added = 1;
+                break;
+            }
+        }
+
+        if(!added) {
+            add(n->children[0], p);
+        }
+    } else {
+        n->entities[n->entity_count++] = p;
+    }
+}
+
+void draw(Vector2 p, Color c) {
+    DrawCircleV(p, 5.0f, c);
+}
+
+void visualize(Node* n) {
+    //DrawRectangleLinesEx(n->bounds, 1.0f, RED);
+
+    if(!is_leaf(n)) {
+        visualize(n->children[0]);
+        visualize(n->children[1]);
+        visualize(n->children[2]);
+        visualize(n->children[3]);
+    }
+
+    Vector2 m_pos = GetMousePosition();
+    
+    if(inside(n, m_pos)) {
+        //DrawRectangleLinesEx(n->bounds, 1.0f, BLUE);
+        for(int i = 0; i < n->entity_count; i++) {
+            if(CheckCollisionCircles(m_pos, 1.0f, n->entities[i], 5.0f)) {
+                draw(n->entities[i], GREEN);
+            } else {
+                draw(n->entities[i], WHITE);
+            }
+        }
+    } else {
+        for(int i = 0; i < n->entity_count; i++) {
+            draw(n->entities[i], WHITE);
+        }
+    }
+}
+
+int main() {
+    const int width = 800;
+    const int height = 600;
+    InitWindow(width, height, "quadtree");
+
+    Node* root = create_node((Rectangle){ 0.0f, 0.0f, width, height });
+
+    for(int i = 0; i < 5000; i++) {
+        add(root, (Vector2){ GetRandomValue(0, width), GetRandomValue(0, height) });
+    }
+
+    while(!WindowShouldClose()) {
+        /*if(IsMouseButtonPressed(MOUSE_LEFT_BUTTON)) {
+            add(root, GetMousePosition());
+        }*/
+
+        BeginDrawing();
+        {
+            ClearBackground(BLACK);
+            visualize(root);
+            DrawFPS(10, 10);
+        }
+        EndDrawing();
+    }
+
+    CloseWindow();
+}

quadtree/naive.c

@@ -0,0 +1,35 @@
+#include <raylib.h>
+
+int main() {
+    const int width = 800;
+    const int height = 600;
+    InitWindow(width, height, "naive");
+
+    const int size = 5000;
+    Vector2 data[size];
+    for(int i = 0; i < size; i++) {
+        data[i] = (Vector2){ GetRandomValue(0, 800), GetRandomValue(0, 600) };
+    }
+
+    while(!WindowShouldClose()) {
+        BeginDrawing();
+        {
+            ClearBackground(BLACK);
+
+            for(int i = 0; i < size; i++) {
+                if(CheckCollisionCircles(GetMousePosition(), 1.0f, data[i], 5.0f)) {
+                    DrawCircleV(data[i], 5.0f, GREEN);
+                } else {
+                    DrawCircleV(data[i], 5.0f, WHITE);
+                }
+            }
+
+            DrawFPS(10, 10);
+        }
+        EndDrawing();
+    }
+
+    CloseWindow();
+
+    return 0;
+}