Simple raylib example which draws lines on the screen.

raylib-lines.c

/*
 * raylib-lines.c
 *
 * To compile:
 *   clang -Wall $(pkg-config --cflags raylib) -o raylib-lines raylib-lines.c $(pkg-config --libs raylib)
 *
 * Copyright (C) 2022 Marco Pantaleoni.
 */

#include <time.h>
#include <stdlib.h>

#include "raylib.h"

#define N_COLORS 20

// for raylib, see:
//   - https://www.raylib.com/cheatsheet/cheatsheet.html
//   - https://github.com/raysan5/raylib/wiki

int main(void) {
    const int screenWidth = 800;
    const int screenHeight = 600;

    InitWindow(screenWidth, screenHeight, "drawing lines");

    SetTargetFPS(60);               // Set our "game" to run at 60 frames-per-second

    Image offscreen = GenImageColor(screenWidth, screenHeight, RAYWHITE);

    Color colors[N_COLORS] = { 0 };
    for (int i = 0; i < N_COLORS; i++) colors[i] = (Color){ GetRandomValue(10, 250), GetRandomValue(10, 150), GetRandomValue(10, 100), 255 };

    // Main "game" loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        // Update

        ImageDrawLine(&offscreen,
            GetRandomValue(10, offscreen.width-10), GetRandomValue(10, offscreen.height-10),
            GetRandomValue(10, offscreen.width-10), GetRandomValue(10, offscreen.height-10),
            colors[GetRandomValue(0, N_COLORS-1)]);

        Texture2D texture = LoadTextureFromImage(offscreen);      // Image converted to texture, uploaded to GPU memory (VRAM)
        // UnloadImage(offscreen);   // Once image has been converted to texture and uploaded to VRAM, it can be unloaded from RAM

        // Draw
        //----------------------------------------------------------------------------------
        BeginDrawing();

            ClearBackground(RAYWHITE);

            DrawTexture(texture, screenWidth/2 - texture.width/2, screenHeight/2 - texture.height/2, WHITE);

            // DrawCircleV(ballPosition, 50, MAROON);

        EndDrawing();
        //----------------------------------------------------------------------------------
    }

    // De-Initialization
    //--------------------------------------------------------------------------------------
    CloseWindow();        // Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}