initial commit

.gitignore

@@ -0,0 +1,2 @@
+main.o
+app

Makefile

@@ -0,0 +1,21 @@
+CC = gcc
+CFLAGS = -Wall -Wextra -std=c17 `sdl2-config --cflags`
+LDFLAGS = `sdl2-config --libs`
+
+SRC = $(wildcard *.c)
+OBJ = $(SRC:.c=.o)
+TARGET = app
+
+all: $(TARGET)
+
+$(TARGET): $(OBJ)
+	$(CC) $(OBJ) -o $(TARGET) $(LDFLAGS)
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+run: $(TARGET)
+	./$(TARGET)
+
+clean:
+	rm -f $(OBJ) $(TARGET)

main.c

@@ -0,0 +1,177 @@
+#include <SDL2/SDL.h>
+#include <SDL2/SDL_render.h>
+#include <stdlib.h>
+
+#define WINDOW_W 800
+#define WINDOW_H 600
+
+#define NUM_RAINDROPS       300
+#define MAX_WIND            30
+#define GRAVITY             400
+#define GRAVITY_DIFF        50 // idk, maybe some downward or upward wind causing resistance
+#define RAINDROP_WIDTH      2
+#define RAINDROP_MAX_HEIGHT 30
+#define RAINDROP_MIN_HEIGHT 10
+
+#define BACKGROUND_R 20
+#define BACKGROUND_G 20
+#define BACKGROUND_B 20
+#define BACKGROUND_A 255
+#define RAINDROP_R   156
+#define RAINDROP_G   174
+#define RAINDROP_B   255
+#define RAINDROP_A   255
+
+typedef struct {
+    float x;
+    float y;
+    float accelerationX;
+    float accelerationY;
+    int   width;
+    int   height;
+} RAINDROP;
+
+float rand_float(float min, float max)
+{
+    float scale = (float)rand() / (float)RAND_MAX;
+    return min + scale * (max - min);
+}
+
+void reset_raindrop(RAINDROP *d)
+{
+    d->x             = rand_float(0, WINDOW_W);
+    d->y             = rand_float(-1 * WINDOW_H, 0);
+    d->accelerationX = rand_float(-1 * MAX_WIND, MAX_WIND);
+    d->accelerationY = rand_float(GRAVITY - GRAVITY_DIFF, GRAVITY + GRAVITY_DIFF);
+    d->width         = RAINDROP_WIDTH;
+    d->height        = rand() % RAINDROP_MAX_HEIGHT + RAINDROP_MIN_HEIGHT;
+}
+
+int main(void)
+{
+    if (SDL_Init(SDL_INIT_VIDEO) != 0)
+    {
+        SDL_Log("Error initializing: %s", SDL_GetError());
+        return 1;
+    }
+
+    SDL_Window   *window;
+    SDL_Renderer *renderer;
+
+    window = SDL_CreateWindow(
+        "SDL2 Window",
+        SDL_WINDOWPOS_CENTERED,
+        SDL_WINDOWPOS_CENTERED,
+        WINDOW_W,
+        WINDOW_H,
+        SDL_WINDOW_SHOWN
+    );
+
+    if (!window)
+    {
+        SDL_Log("Error creating window: %s", SDL_GetError());
+        SDL_Quit();
+        return 1;
+    }
+
+    renderer = SDL_CreateRenderer(
+        window,
+        -1,
+        SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC
+    );
+
+    if (!renderer)
+    {
+        SDL_Log("Error creating renderer: %s", SDL_GetError());
+        SDL_DestroyWindow(window);
+        SDL_Quit();
+        return 1;
+    }
+
+    int       running;
+    SDL_Event event;
+    Uint32    last_time;
+
+    last_time = SDL_GetTicks();
+    running   = 1;
+
+    // Create drops
+    RAINDROP drops[NUM_RAINDROPS];
+    for (int i = 0; i < NUM_RAINDROPS; i++)
+    {
+        reset_raindrop(&drops[i]);
+    }
+
+    while (running)
+    {
+        while (SDL_PollEvent(&event))
+        {
+            if (event.type == SDL_QUIT)
+            {
+                running = 0;
+            }
+        }
+
+        // delta time
+        Uint32 now;
+        float delta;
+
+        now = SDL_GetTicks();
+        delta = (now - last_time) / 1000.0f; // seconds
+        last_time = now;
+
+        // clear scren
+        SDL_SetRenderDrawColor(
+            renderer,
+            BACKGROUND_R,
+            BACKGROUND_G,
+            BACKGROUND_B,
+            BACKGROUND_A
+        );
+        SDL_RenderClear(renderer);
+
+
+        // render raindrops
+        for (int i = 0; i < NUM_RAINDROPS; i++)
+        {
+            RAINDROP *drop;
+            drop = &drops[i];
+
+            drop->x += delta * drop->accelerationX;
+            drop->y += delta * drop->accelerationY;
+
+            if (drop->y > WINDOW_H ||
+                drop->x < -1 * RAINDROP_WIDTH ||
+                drop->x > WINDOW_W + RAINDROP_WIDTH)
+            {
+                reset_raindrop(drop);
+            }
+
+            SDL_Rect raindrop;
+
+            raindrop = (SDL_Rect){
+                (int) drop->x,
+                (int) drop->y,
+                drop->width,
+                drop->height
+            };
+
+            // Set brush color and draw
+            SDL_SetRenderDrawColor(
+                renderer,
+                RAINDROP_R,
+                RAINDROP_G,
+                RAINDROP_B,
+                RAINDROP_A
+            );
+            SDL_RenderFillRect(renderer, &raindrop);
+        }
+
+        SDL_RenderPresent(renderer);
+    }
+
+    SDL_DestroyRenderer(renderer);
+    SDL_DestroyWindow(window);
+    SDL_Quit();
+    return 0;
+}