REVIEWED: example shapes_hilbert_curve #5454

Make it more didactic and dynamic, avoid global variables

examples/shapes/shapes_hilbert_curve.c

@@ -6,7 +6,7 @@
 *
 *   Example originally created with raylib 5.6, last time updated with raylib 5.6
 *
-*   Example contributed by Hamza RAHAL (@hmz-rhl)
+*   Example contributed by Hamza RAHAL (@hmz-rhl) and reviewed by Ramon Santamaria (@raysan5)
 *
 *   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
 *   BSD-like license that allows static linking with closed source software
@@ -17,48 +17,18 @@
 
 
 #include "raylib.h"
-#include "raymath.h"
-#include <stdlib.h>
-#include <stdio.h>
 
-const int screenWidth = 800;
+#define RAYGUI_IMPLEMENTATION
+#include "raygui.h"
 
-const int screenHeight = 450;
-
-int order = 2;
-
-int total;
-
-int counter = 0;
-
-Vector2 *hilbertPath = 0;
-
-const Vector2 hilbertPoints[4] =
-{
-    [0] = {
-        .x = 0,
-        .y = 0
-    },
-    [1] = {
-        .x = 0,
-        .y = 1
-    },
-    [2] = {
-        .x = 1,
-        .y = 1
-    },
-    [3] = {
-        .x = 1,
-        .y = 0
-    },
-};
+#include <stdlib.h>     // Required for: calloc(), free()
 
 //------------------------------------------------------------------------------------
 // Module Functions Declaration
 //------------------------------------------------------------------------------------
-Vector2 Hilbert(int index);
-
-void InitHilbertPath(void);
+static Vector2 *LoadHilbertPath(int order, float size, int *strokeCount);
+static void UnloadHilbertPath(Vector2 *hilbertPath);
+static Vector2 ComputeHilbertStep(int order, int index);
 
 //------------------------------------------------------------------------------------
 // Program main entry point
@@ -67,13 +37,23 @@ int main(void)
 {
     // Initialization
     //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
 
-    InitWindow(screenWidth, screenHeight, "raylib [shapes] example - hilbert curve example");
+    InitWindow(screenWidth, screenHeight, "raylib [shapes] example - hilbert curve");
 
-    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
-
-    InitHilbertPath();
+    int order = 2;
+    float size = GetScreenHeight();
+    int strokeCount = 0;
+    Vector2 *hilbertPath = LoadHilbertPath(order, size, &strokeCount);
     
+    int prevOrder = order;
+    int prevSize = (int)size;       // NOTE: Size from slider is float but for comparison we use int
+    int counter = 0;
+    float thick = 2.0f;
+    bool animate = true;
+    
+    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
     //--------------------------------------------------------------------------------------
 
     // Main game loop
@@ -82,34 +62,52 @@ int main(void)
     {
         // Update
         //----------------------------------------------------------------------------------
-        if ((IsKeyPressed(KEY_UP)) && (order < 8))
+        // Check if order or size have changed to regenerate
+        // NOTE: Size from slider is float but for comparison we use int
+        if ((prevOrder != order) || (prevSize != (int)size))
         {
-            counter = 0;
-            ++order;
-            InitHilbertPath();
-        }
-        else if((IsKeyPressed(KEY_DOWN)) && (order > 1))
-        {
-            counter = 0;
-            --order;
-            InitHilbertPath();
+            UnloadHilbertPath(hilbertPath);
+            hilbertPath = LoadHilbertPath(order, size, &strokeCount);
+            
+            if (animate) counter = 0;
+            else counter = strokeCount;
+            
+            prevOrder = order;
+            prevSize = size;
         }
         //----------------------------------------------------------------------------------
         
         // Draw
         //--------------------------------------------------------------------------
         BeginDrawing();
-        DrawText(TextFormat("(press UP or DOWN to change)\norder : %d", order), screenWidth/2 + 70, 25, 20, WHITE);
         
-        if(counter < total)
-        {
-            ClearBackground(BLACK);
-            for (int i = 1; i <= counter; i++)
+            ClearBackground(RAYWHITE);
+
+            if (counter < strokeCount)
             {
-                DrawLineV(hilbertPath[i], hilbertPath[i-1], ColorFromHSV(((float)i / total) * 360.0f, 1.0f, 1.0f));
+                // Draw Hilbert path animation, one stroke every frame
+                for (int i = 1; i <= counter; i++)
+                {
+                    DrawLineEx(hilbertPath[i], hilbertPath[i - 1], thick, ColorFromHSV(((float)i/strokeCount)*360.0f, 1.0f, 1.0f));
+                }
+                
+                counter += 1;
             }
-            counter += 1;
-        }
+            else
+            {
+                // Draw full Hilbert path
+                for (int i = 1; i < strokeCount; i++)
+                {
+                    DrawLineEx(hilbertPath[i], hilbertPath[i - 1], thick, ColorFromHSV(((float)i/strokeCount)*360.0f, 1.0f, 1.0f));
+                }
+            }
+        
+            // Draw UI using raygui
+            GuiCheckBox((Rectangle){ 450, 50, 20, 20 }, "ANIMATE GENERATION ON CHANGE", &animate);
+            GuiSpinner((Rectangle){ 585, 100, 180, 30 }, "HILBERT CURVE ORDER:  ", &order, 2, 8, false);
+            GuiSlider((Rectangle){ 524, 150, 240, 24 }, "THICKNESS:  ", NULL, &thick, 1.0f, 10.0f);
+            GuiSlider((Rectangle){ 524, 190, 240, 24 }, "TOTAL SIZE: ", NULL, &size, 10.0f, GetScreenHeight()*1.5f);
+        
         EndDrawing();
         //--------------------------------------------------------------------------
     }
@@ -117,8 +115,9 @@ int main(void)
 
     // De-Initialization
     //--------------------------------------------------------------------------------------
+    UnloadHilbertPath(hilbertPath);
+    
     CloseWindow();        // Close window and OpenGL context
-    MemFree(hilbertPath);
     //--------------------------------------------------------------------------------------
     return 0;
 }
@@ -126,62 +125,72 @@ int main(void)
 //------------------------------------------------------------------------------------
 // Module Functions Definition
 //------------------------------------------------------------------------------------
-
-// calculate U positions
-Vector2 Hilbert(int index)
+// Load the whole Hilbert Path (including each U and their link)
+static Vector2 *LoadHilbertPath(int order, float size, int *strokeCount)
 {
+    int N = 1 << order;
+    float len = size/N;
+    *strokeCount = N*N;
 
-    int hiblertIndex = index&3;
-    Vector2 vect = hilbertPoints[hiblertIndex];
-    float temp;
-    int len;
-
-    for (int j = 1; j < order; j++)
+    Vector2 *hilbertPath = (Vector2 *)RL_CALLOC(*strokeCount, sizeof(Vector2));
+    
+    for (int i = 0; i < *strokeCount; i++)
     {
-        index = index>>2;
-        hiblertIndex = index&3;
-        len = 1<<j;
-        switch (hiblertIndex)
-        {
-            case 0:
-                temp = vect.x;
-                vect.x = vect.y;
-                vect.y = temp;
-                break;
-            case 2:
-                vect.x += len;
-            case 1:
-                vect.y += len;
-                break;
-            case 3:
-                temp = len - 1 - vect.x;
-                vect.x = 2*len - 1 - vect.y;
-                vect.y = temp;
-                break;
-        }
-    }
-    return vect;
-}
-
-// Calculate the whole Hilbert Path (including each U and their link)
-void InitHilbertPath(void)
-{
-    int N;
-    float len;
-    N = 1<<order;
-    total = N*N;
-    MemFree(hilbertPath);
-    hilbertPath = NULL;
-    hilbertPath = (Vector2*)MemAlloc(sizeof(Vector2)*total);
-    if(hilbertPath == NULL)
-    {
-        printf("%s: malloc failed\n", __func__);
-    }
-    len = (float)screenHeight/N;
-    for (int i = 0; i < total; i++)
-    {
-        hilbertPath[i] = Hilbert(i);
+        hilbertPath[i] = ComputeHilbertStep(order, i);
         hilbertPath[i].x = hilbertPath[i].x*len + len/2.0f;
         hilbertPath[i].y = hilbertPath[i].y*len + len/2.0f;
     }
+    
+    return hilbertPath;
+}
+
+// Unload Hilbert path data
+static void UnloadHilbertPath(Vector2 *hilbertPath)
+{
+    RL_FREE(hilbertPath);
+}
+
+// Compute Hilbert path U positions
+static Vector2 ComputeHilbertStep(int order, int index)
+{
+    // Hilbert points base pattern
+    static const Vector2 hilbertPoints[4] = {
+        [0] = { .x = 0, .y = 0 },
+        [1] = { .x = 0, .y = 1 },
+        [2] = { .x = 1, .y = 1 },
+        [3] = { .x = 1, .y = 0 },
+    };
+       
+    int hilbertIndex = index&3;
+    Vector2 vect = hilbertPoints[hilbertIndex];
+    float temp = 0.0f;
+    int len = 0;
+
+    for (int j = 1; j < order; j++)
+    {
+        index = index >> 2;
+        hilbertIndex = index&3;
+        len = 1 << j;
+        
+        switch (hilbertIndex)
+        {
+            case 0:
+            {
+                temp = vect.x;
+                vect.x = vect.y;
+                vect.y = temp;
+            } break;
+            case 2: vect.x += len;
+            case 1: vect.y += len; break;
+            case 3:
+            {
+                temp = len - 1 - vect.x;
+                vect.x = 2*len - 1 - vect.y;
+                vect.y = temp;
+            } break;
+            default: break;
+        }
+    }
+    
+    return vect;
 }