Implement seeded random

examples/core_random_colors.c

@@ -0,0 +1,47 @@
+#include "raylib.h"
+
+void raylib_js_set_entry(void (*entry)(void));
+
+unsigned int framesCounter = 0;
+int r = 150;
+int g = 150;
+int b = 150;
+
+void GameFrame()
+{
+    BeginDrawing();
+    ClearBackground(CLITERAL(Color){r, g, b, 255});
+    framesCounter++;
+
+    if (((framesCounter / 120) % 2) == 1)
+    {
+      r = GetRandomValue(50, 255);
+      g = GetRandomValue(50, 255);
+      b = GetRandomValue(50, 255);
+      framesCounter = 0;
+    }
+
+    ClearBackground(CLITERAL(Color){r, g, b, 255});
+    DrawText("Every 2 seconds a new random color is generated", 130, 100, 20, BLACK);
+    EndDrawing();
+}
+
+int main(void)
+{
+  const int screenWidth = 800;
+  const int screenHeight = 450;
+
+  InitWindow(screenWidth, screenHeight, "Random colors");
+
+  SetTargetFPS(60);
+#ifdef PLATFORM_WEB
+    raylib_js_set_entry(GameFrame);
+#else
+    while (!WindowShouldClose())
+    {
+        GameFrame();
+    }
+    CloseWindow();
+#endif
+    return 0;
+}

index.html

@@ -68,7 +68,7 @@
     <script>
         const wasmPaths = {
             "tsoding": ["tsoding_ball", "tsoding_snake",],
-            "core": ["core_basic_window", "core_basic_screen_manager", "core_input_keys", "core_input_mouse_wheel",],
+            "core": ["core_basic_window", "core_basic_screen_manager", "core_input_keys", "core_input_mouse_wheel","core_random_colors",],
             "shapes": ["shapes_colors_palette"],
             "text": ["text_writing_anim"],
             "textures": ["textures_logo_raylib"],

nob.c

@@ -48,6 +48,11 @@ Example examples[] = {
         .bin_path   = "./build/text_writing_anim",
         .wasm_path  = "./wasm/text_writing_anim.wasm",
     },
+    {
+        .src_path   = "./examples/core_random_colors.c",
+        .bin_path   = "./build/core_random_colors",
+        .wasm_path  = "./wasm/core_random_colors.wasm",
+    },
 };
 
 bool build_native(void)

raylib.js

@@ -37,6 +37,7 @@ class RaylibJs {
         this.ctx = undefined;
         this.dt = undefined;
         this.targetFPS = 60;
+        this.seed = undefined;
         this.entryFunction = undefined;
         this.prevPressedKeyState = new Set();
         this.currentPressedKeyState = new Set();
@@ -111,6 +112,7 @@ class RaylibJs {
         this.ctx.canvas.height = height;
         const buffer = this.wasm.instance.exports.memory.buffer;
         document.title = cstr_by_ptr(buffer, title_ptr);
+        this.seed = Date.now();
     }
 
     WindowShouldClose(){
@@ -344,6 +346,19 @@ class RaylibJs {
         this.ctx.fillText(text, posX, posY + fontSize);
     }
 
+    SetRandomSeed(seed) {
+        this.seed = seed;
+    }
+
+    // Here is the simple Park and Miller random number generator instead
+    // of SplitMix64 and Xoshiro128** combo used in raylib. (https://github.com/raysan5/raylib/blob/8a5fd3ac1d481ff978363b80298770ed8eeca9f8/src/external/rprand.h#L120)
+    // TODO: We'll need to implement the same algorithm in the future
+    GetRandomValue(min, max) {
+        if (min > max) [min, max] = [max, min];
+        this.seed = this.seed * 16807 % 2147483647;
+        return (this.seed % (max - min + 1)) + min;
+    }
+
     raylib_js_set_entry(entry) {
         this.entryFunction = this.wasm.instance.exports.__indirect_function_table.get(entry);
     }