Create Example_-_Additive_Blend_Smoke_trail.c

Example_-_Additive_Blend_Smoke_trail.c

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+//
+// Modified example of raylib.com !!
+//
+// Will change later on..
+//
+// I was watching a video of the game 'Gaia beyond' a space rpg where there were tiny space ships
+// and rockets with trails. I wanted to head into the direction of coding a small version of this.
+// Here I looked into how to do the smoke trails.. I'm not using a external image for the smoke
+// but created one in the code here.
+//
+
+#include "raylib.h"
+
+#define MAX_PARTICLES 200
+
+// Particle structure with basic data
+typedef struct {
+    Vector2 position;
+    Color color;
+    float alpha;
+    float size;
+    float rotation;
+    bool active;        // NOTE: Use it to activate/deactive particle
+} Particle;
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [core] example - generate random values");
+
+
+    // Particles pool, reuse them!
+    Particle mouseTail[MAX_PARTICLES] = { 0 };
+
+    // Initialize particles
+    for (int i = 0; i < MAX_PARTICLES; i++)
+    {
+        mouseTail[i].position = (Vector2){ 0, 0 };
+        mouseTail[i].color = GRAY;//(Color){ GetRandomValue(0, 255), GetRandomValue(0, 255), GetRandomValue(0, 255), 255 };
+        mouseTail[i].alpha = 1.0f;
+        mouseTail[i].size = (float)GetRandomValue(1, 30)/20.0f;
+        mouseTail[i].rotation = (float)GetRandomValue(0, 360);
+        mouseTail[i].active = false;
+    }
+
+    float gravity = 3.0f;
+
+
+     // Create a Image in memory
+    RenderTexture2D smoke = LoadRenderTexture(32, 32);
+    
+    BeginTextureMode(smoke);    
+    ClearBackground(BLANK);
+    // Draw a base image(dark edges and white inside) for the additive blend mode smoke trail.
+    for(int i=0;i<16;i++){
+        BeginTextureMode(smoke); 
+        int c=255/16*i;
+        DrawCircle(16,16,16-i/2,(Color){c,c,c,255});
+        EndTextureMode();               // This needs to be called after every different draw command used. Do not forget to use begintexture also..
+    }
+
+    EndTextureMode();               // This needs to be called after every different draw command used. Do not forget to use begintexture also..
+ 
+
+    // Start at blend additive mode for the white smoke trial.
+    int blending = BLEND_ADDITIVE;
+    
+ 
+    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        //----------------------------------------------------------------------------------
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+            
+ 
+
+
+        // Update
+        //----------------------------------------------------------------------------------
+
+        // Activate one particle every frame and Update active particles
+        // NOTE: Particles initial position should be mouse position when activated
+        // NOTE: Particles fall down with gravity and rotation... and disappear after 2 seconds (alpha = 0)
+        // NOTE: When a particle disappears, active = false and it can be reused.
+        for (int i = 0; i < MAX_PARTICLES; i++)
+        {
+            if (!mouseTail[i].active)
+            {
+                mouseTail[i].active = true;
+                mouseTail[i].alpha = 1.0f;
+                mouseTail[i].position = GetMousePosition();
+                i = MAX_PARTICLES;
+            }
+        }
+
+        for (int i = 0; i < MAX_PARTICLES; i++)
+        {
+            if (mouseTail[i].active)
+            {
+                mouseTail[i].position.y += gravity/2;
+                mouseTail[i].alpha -= 0.005f;
+
+                if (mouseTail[i].alpha <= 0.0f) mouseTail[i].active = false;
+
+                mouseTail[i].rotation += 2.0f;
+            }
+        }
+
+        if (IsKeyPressed(KEY_SPACE))
+        {
+            if (blending == BLEND_ALPHA) blending = BLEND_ADDITIVE;
+            else blending = BLEND_ALPHA;
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(DARKGRAY);
+
+            BeginBlendMode(blending);
+
+                // Draw active particles
+                for (int i = 0; i < MAX_PARTICLES; i++)
+                {
+                    if (mouseTail[i].active) DrawTexturePro(smoke.texture, (Rectangle){ 0.0f, 0.0f, (float)smoke.texture.width, (float)smoke.texture.height },
+                                                           (Rectangle){ mouseTail[i].position.x, mouseTail[i].position.y, smoke.texture.width*mouseTail[i].size, smoke.texture.height*mouseTail[i].size },
+                                                           (Vector2){ (float)(smoke.texture.width*mouseTail[i].size/2.0f), (float)(smoke.texture.height*mouseTail[i].size/2.0f) }, mouseTail[i].rotation,
+                                                           Fade(mouseTail[i].color, mouseTail[i].alpha));
+                }
+
+            EndBlendMode();
+
+            DrawText("PRESS SPACE to CHANGE BLENDING MODE", 180, 20, 20, BLACK);
+
+            if (blending == BLEND_ALPHA) DrawText("ALPHA BLENDING", 290, screenHeight - 40, 20, BLACK);
+            else DrawText("ADDITIVE BLENDING", 280, screenHeight - 40, 20, RAYWHITE);
+
+
+
+
+
+
+
+
+
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadRenderTexture(smoke);    // Unload render texture
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}