ported example 3d camera free (#162)

build.zig

@@ -231,6 +231,11 @@ pub fn build(b: *std.Build) !void {
             .path = "examples/core/3d_camera_first_person.zig",
             .desc = "Simple first person demo",
         },
+        .{
+            .name = "3d_camera_free",
+            .path = "examples/core/3d_camera_free.zig",
+            .desc = "Shows basic 3d camera initialization",
+        },
         .{
             .name = "2d_camera_mouse_zoom",
             .path = "examples/core/2d_camera_mouse_zoom.zig",

examples/core/3d_camera_free.zig

@@ -0,0 +1,69 @@
+// A raylib port of https://github.com/raysan5/raylib/blob/master/examples/core/core_3d_camera_free.c
+
+const rl = @import("raylib");
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+pub fn main() anyerror!void {
+    // Initialization
+    //--------------------------------------------------------------------------------
+    const screenWidth = 800;
+    const screenHeight = 450;
+
+    rl.initWindow(screenWidth, screenHeight, "raylib [core] example - 3d camera free");
+    defer rl.closeWindow(); // Close window and OpenGL context
+
+    // Define the camera to look into our 3d world
+    var camera = rl.Camera{
+        .position = rl.Vector3.init(10, 10, 10),
+        .target = rl.Vector3.init(0, 0, 0),
+        .up = rl.Vector3.init(0, 1, 0),
+        .fovy = 45,
+        .projection = rl.CameraProjection.camera_perspective,
+    };
+
+    const cubePosition = rl.Vector3.init(0, 0, 0);
+
+    rl.disableCursor(); // Limit cursor to relative movement inside the window
+    rl.setTargetFPS(60); // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!rl.windowShouldClose()) { // Detect window close button or ESC key
+        // Update
+        //-----------------------------------------------------------------------------
+        camera.update(rl.CameraMode.camera_free);
+
+        if (rl.isKeyPressed(rl.KeyboardKey.key_z)) {
+            camera.target = rl.Vector3.init(0, 0, 0);
+        }
+        //-----------------------------------------------------------------------------
+
+        // Draw
+        //-----------------------------------------------------------------------------
+        rl.beginDrawing();
+        defer rl.endDrawing();
+
+        rl.clearBackground(rl.Color.ray_white);
+
+        {
+            camera.begin();
+            defer camera.end();
+
+            rl.drawCube(cubePosition, 2, 2, 2, rl.Color.red);
+            rl.drawCubeWires(cubePosition, 2, 2, 2, rl.Color.maroon);
+
+            rl.drawGrid(10, 1);
+        }
+
+        rl.drawRectangle(10, 10, 320, 93, rl.Color.fade(rl.Color.sky_blue, 0.5));
+        rl.drawRectangleLines(10, 10, 320, 93, rl.Color.blue);
+
+        rl.drawText("Free camera default controls:", 20, 20, 10, rl.Color.black);
+        rl.drawText("- Mouse Wheel to Zoom in-out", 40, 40, 10, rl.Color.dark_gray);
+        rl.drawText("- Mouse Wheel Pressed to Pan", 40, 60, 10, rl.Color.dark_gray);
+        rl.drawText("- Z to zoom to (0, 0, 0)", 40, 80, 10, rl.Color.dark_gray);
+        //-----------------------------------------------------------------------------
+    }
+}