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106 行
4.2 KiB
106 行
4.2 KiB
#include "raylib.h"
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#include "raymath.h"
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/*******************************************************************************************
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*
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* raylib [shapes] example - Draw a mouse trail (position history)
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*
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* Example complexity rating: [★☆☆☆] 1/4
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*
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* Example originally created with raylib 5.6
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*
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* Example contributed by [Balamurugan R] (@[Bala050814]]) and reviewed by [Ray] (@raysan5)
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*
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* Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
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* BSD-like license that allows static linking with closed source software
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*
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* Copyright (c) 2024 [Balamurugan R] (@[Bala050814])
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*
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********************************************************************************************/
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// Define the maximum number of positions to store in the trail
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#define MAX_TRAIL_LENGTH 30
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//------------------------------------------------------------------------------------
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// Program main entry point
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//------------------------------------------------------------------------------------
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int main(void)
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{
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// Initialization
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//--------------------------------------------------------------------------------------
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const int screenWidth = 800;
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const int screenHeight = 450;
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InitWindow(screenWidth, screenHeight, "raylib [shapes] example - Draw a mouse trail");
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// Array to store the history of mouse positions (our fixed-size queue)
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Vector2 trailPositions[MAX_TRAIL_LENGTH] = { 0 };
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SetTargetFPS(60);
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//--------------------------------------------------------------------------------------
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// Main game loop
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while (!WindowShouldClose()) // Detect window close button or ESC key
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{
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// Update
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//----------------------------------------------------------------------------------
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Vector2 mousePosition = GetMousePosition();
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// 1. Shift all existing positions backward by one slot in the array
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// The last element (the oldest position) is dropped.
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for (int i = MAX_TRAIL_LENGTH - 1; i > 0; i--)
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{
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trailPositions[i] = trailPositions[i - 1];
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}
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// 2. Store the new, current mouse position at the start of the array (Index 0)
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trailPositions[0] = mousePosition;
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//----------------------------------------------------------------------------------
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// Draw
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//----------------------------------------------------------------------------------
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BeginDrawing();
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// Use BLACK for a darker background to make the colored trail pop
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ClearBackground(BLACK);
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// 3. Draw the trail by looping through the history array
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for (int i = 0; i < MAX_TRAIL_LENGTH; i++)
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{
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// Ensure we skip drawing if the array hasn't been fully filled on startup
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if (trailPositions[i].x != 0.0f || trailPositions[i].y != 0.0f)
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{
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// Calculate relative trail strength (ratio is near 1.0 for new, near 0.0 for old)
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float ratio = (float)(MAX_TRAIL_LENGTH - i) / MAX_TRAIL_LENGTH;
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// Fade effect: oldest positions are more transparent
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// Fade (color, alpha) - alpha is 0.5 to 1.0 based on ratio
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Color trailColor = Fade(SKYBLUE, ratio * 0.5f + 0.5f);
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// Size effect: oldest positions are smaller
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float trailRadius = 15.0f * ratio;
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DrawCircleV(trailPositions[i], trailRadius, trailColor);
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}
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}
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// Draw a distinct white circle for the current mouse position (Index 0)
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DrawCircleV(mousePosition, 15.0f, WHITE);
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DrawText("Move the mouse to see the trail effect!",
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10, screenHeight - 30, 20, LIGHTGRAY);
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EndDrawing();
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//----------------------------------------------------------------------------------
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}
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// De-Initialization
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//--------------------------------------------------------------------------------------
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// No resources loaded, nothing to unload.
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CloseWindow(); // Close window and OpenGL context
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//--------------------------------------------------------------------------------------
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return 0;
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}
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