Add raylib tutorial

raylib.html.markdown

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+---
+category: tool
+tool: raylib
+filename: learnraylib.c
+contributors:
+    - ["Nikolas Wipper", "https://notnik.cc"]
+---
+
+**raylib** is a cross-platform easy-to-use graphics library, built around
+OpenGL 1.1, 2.1, 3.3 and OpenGL ES 2.0. Even though it is written in C
+it has bindings to over 50 different languages. This tutorial will use C,
+more specifically C99.
+
+```c
+#include <raylib.h>
+
+int main(void)
+{
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    // Before initialising raylib we can set configuration flags
+    SetConfigFlags(FLAG_MSAA_4X_HINT | FLAG_VSYNC_HINT);
+
+    // raylib doesn't require us to store any instance structures
+    // At the moment raylib can handle only one window at a time
+    InitWindow(screenWidth, screenHeight, "MyWindow");
+
+    // Set our game to run at 60 frames-per-second
+    SetTargetFPS(60);
+
+    // Set a key that closes the window
+    // Could be 0 for no key
+    SetExitKey(KEY_DELETE);
+
+    // raylib defines two types of cameras: Camera3D and Camera2D
+    // Camera is a typedef for Camera3D
+    Camera camera = {
+            .position = {0.0f, 0.0f, 0.0f},
+            .target   = {0.0f, 0.0f, 1.0f},
+            .up       = {0.0f, 1.0f, 0.0f},
+            .fovy     = 70.0f,
+            .type     = CAMERA_PERSPECTIVE
+    };
+
+    // raylib supports loading of models, animations, images and sounds
+    // from various different file formats
+    Model myModel = LoadModel("my_model.obj");
+    Font someFont = LoadFont("some_font.ttf");
+
+    // Creates a 100x100 render texture
+    RenderTexture renderTexture = LoadRenderTexture(100, 100);
+
+    // WindowShouldClose checks if the user is closing the window
+    // This might happen using a shortcut, window controls
+    // or the key we set earlier
+    while (!WindowShouldClose())
+    {
+
+        // BeginDrawing needs to be called before any draw call
+        BeginDrawing();
+        {
+
+            // Sets the background to a certain color
+            ClearBackground(BLACK);
+
+            if (IsKeyDown(KEY_SPACE))
+                DrawCircle(400, 400, 30, GREEN);
+
+            // Simple draw text
+            DrawText("Congrats! You created your first window!",
+                     190, // x
+                     200, // y
+                     20,  // font size
+                     LIGHTGRAY
+            );
+
+            // For most functions there are several versions
+            // These are usually postfixed with Ex, Pro, V
+            // or sometimes Rec, Wires (only for 3D), Lines (only for 2D)
+            DrawTextEx(someFont,
+                       "Text in another font",
+                       (Vector2) {10, 10},
+                       20, // font size
+                       2,  // spacing
+                       LIGHTGRAY);
+
+            // Required for drawing 3D, has 2D equivalent
+            BeginMode3D(camera);
+            {
+
+                DrawCube((Vector3) {0.0f, 0.0f, 3.0f},
+                         1.0f, 1.0f, 1.0f, RED);
+
+                // White tint when drawing will keep the original color
+                DrawModel(myModel, (Vector3) {0.0f, 0.0f, 3.0f},
+                          1.0f, //Scale
+                          WHITE);
+
+            }
+            // End 3D mode so we can draw normally again
+            EndMode3D();
+
+            // Start drawing onto render texture
+            BeginTextureMode(renderTexture);
+            {
+
+                // It behaves the same as if we just called `BeginDrawing()`
+
+                ClearBackground(RAYWHITE);
+
+                BeginMode3D(camera);
+                {
+
+                    DrawGrid(10, // Slices
+                             1.0f // Spacing
+                    );
+
+                }
+                EndMode3D();
+
+            }
+            EndTextureMode();
+
+            // render textures have a Texture2D field
+            DrawTexture(renderTexture.texture, 40, 378, BLUE);
+
+        }
+        EndDrawing();
+    }
+
+    // Unloading loaded objects
+    UnloadFont(someFont);
+    UnloadModel(myModel);
+
+    // Close window and OpenGL context
+    CloseWindow();
+
+    return 0;
+}
+
+```
+
+## Further reading
+raylib has some [great examples](https://www.raylib.com/examples.html)
+If you don't like C check out the [raylib bindings](https://github.com/raysan5/raylib/blob/master/BINDINGS.md)