delta example

examples/core/core_delta_time.c

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+/*
+4. Code should follow raylib conventions: https://github.com/raysan5/raylib/wiki/raylib-coding-conventions
+Try to be very organized, using line-breaks appropiately
+
+/*******************************************************************************************
+*
+*   raylib [core] example - delta time
+*
+*   Example complexity rating: [★☆☆☆] 1/4
+*
+*   Example originally created with raylib 5.5
+*
+*   Example contributed by Robin (@RobinsAviary) 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
+*
+*   Copyright (c) 2025-2025 Robin (@RobinsAviary)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+int currentFps = 60;
+
+// Used only in this example in order to allow finer control of the FPS limit.
+void UpdateFPS(int fps)
+{
+    currentFps = fps;
+    SetTargetFPS(currentFps);
+}
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [core] example - delta time");
+
+    // The x positions for each circle.
+    float deltaX = 0;
+    float frameX = 0;
+
+    // The speed applied to both circles.
+    const float speed = 10.0;
+    const int circleRadius = 32;
+
+    // Calculate the visual Y position for both circles.
+    const float deltaY = screenHeight / 3.0;
+    const float frameY = screenHeight * (2.0/3.0);
+
+    SetTargetFPS(currentFps);
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose()) // Detect window close button or ESC key
+    {
+        // Update
+
+        // Update the target FPS based on number key.
+        if (IsKeyPressed(KEY_ONE)) UpdateFPS(10);
+        if (IsKeyPressed(KEY_TWO)) UpdateFPS(20);
+        if (IsKeyPressed(KEY_THREE)) UpdateFPS(30);
+        if (IsKeyPressed(KEY_FOUR)) UpdateFPS(40);
+        if (IsKeyPressed(KEY_FIVE)) UpdateFPS(50);
+        if (IsKeyPressed(KEY_SIX)) UpdateFPS(60);
+        if (IsKeyPressed(KEY_SEVEN)) UpdateFPS(70);
+        if (IsKeyPressed(KEY_EIGHT)) UpdateFPS(80);
+        if (IsKeyPressed(KEY_NINE)) UpdateFPS(90);
+        if (IsKeyPressed(KEY_ZERO)) UpdateFPS(0); // Unlimited framerate
+
+        if (IsKeyPressed(KEY_R)) // Reset both circles' positions when you press R.
+        {
+            deltaX = 0;
+            frameX = 0;
+        }
+
+        // Adjust the FPS target based on the mouse wheel.
+        int mouseWheel = GetMouseWheelMove();
+        if (mouseWheel != 0)
+        {
+            currentFps += mouseWheel;
+            SetTargetFPS(currentFps);
+        }
+
+        // Use of delta time to make the circle look like it's moving at a "consistent" speed regardless of FPS.
+        // Multiply by 6.0 (an arbitrary value) in order to make the speed visually closer to the other circle (at 60 fps), for comparison.
+        deltaX += GetFrameTime() * 6.0 * speed;
+        // This circle can move faster or slower visually depending on the FPS.
+        frameX += .1 * speed;
+
+        // If either circle is off the screen, reset it back to the start.
+        if (deltaX > screenWidth)
+        {
+            deltaX = 0;
+        }
+
+        if (frameX > screenWidth)
+        {
+            frameX = 0;
+        }
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+        ClearBackground(RAYWHITE);
+
+        // Draw both circles to the screen.
+        DrawCircle(deltaX, deltaY, circleRadius, RED);
+        DrawCircle(frameX, frameY, circleRadius, BLUE);
+
+        // Determine what help text to show depending on the current FPS target.
+        char* fpsText;
+
+        if (currentFps <= 0)
+        {
+            if (currentFps < 0)
+            {
+                // Clamp values below 0.
+                currentFps = 0;
+            }
+
+            // Special text for when the FPS target is set to 0 or less, which makes it unlimited.
+            fpsText = TextFormat("fps: unlimited (%i)", GetFPS());
+        }
+        else {
+            fpsText = TextFormat("fps: %i", GetFPS());
+        }
+
+        // Draw the help text
+        DrawText(fpsText, 10, 10, 20, DARKGRAY);
+        DrawText(TextFormat("frame time: %02.02f ms", GetFrameTime()), 10, 30, 20, DARKGRAY);
+        DrawText("use the scroll wheel/number keys to change the fps limit, r to reset", 10, 50, 20, DARKGRAY);
+
+        // Draw the text above the circles.
+        DrawText("x += GetFrameTime() * speed", 10, 90, 20, RED);
+        DrawText("x += speed", 10, 240, 20, BLUE);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}