ported example core 3d picking (#163)

build.zig

@@ -241,7 +241,11 @@ pub fn build(b: *std.Build) !void {
             .path = "examples/core/2d_camera_mouse_zoom.zig",
             .desc = "Shows mouse zoom demo",
         },
-
+        .{
+            .name = "3d_picking",
+            .path = "examples/core/3d_picking.zig",
+            .desc = "Shows picking in 3d mode",
+        },
         .{
             .name = "window_flags",
             .path = "examples/core/window_flags.zig",

examples/core/3d_picking.zig

@@ -0,0 +1,89 @@
+// A raylib-zig port of https://github.com/raysan5/raylib/blob/master/examples/core/core_3d_picking.c
+const rl = @import("raylib");
+
+pub fn main() anyerror!void {
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const screenWidth = 800;
+    const screenHeight = 450;
+
+    rl.initWindow(screenWidth, screenHeight, "raylib-zig [core] example - 3d picking");
+
+    // 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, 1, 0);
+    const cubeSize = rl.Vector3.init(2, 2, 2);
+
+    var ray: rl.Ray = undefined; // Picking line ray
+    var collision: rl.RayCollision = undefined; // Ray collision hit info
+
+    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
+        //----------------------------------------------------------------------------------
+        if (rl.isCursorHidden()) rl.updateCamera(&camera, rl.CameraMode.camera_first_person);
+
+        // Toggle camera controls
+        if (rl.isMouseButtonPressed(rl.MouseButton.mouse_button_right)) {
+            if (rl.isCursorHidden()) rl.enableCursor() else rl.disableCursor();
+        }
+
+        if (rl.isMouseButtonPressed(rl.MouseButton.mouse_button_left)) {
+            if (!collision.hit) {
+                ray = rl.getScreenToWorldRay(rl.getMousePosition(), camera);
+
+                // Check collision between ray and box
+                collision = rl.getRayCollisionBox(ray, rl.BoundingBox{
+                    .max = rl.Vector3.init(cubePosition.x - cubeSize.x / 2, cubePosition.y - cubeSize.y / 2, cubePosition.z - cubeSize.z / 2),
+                    .min = rl.Vector3.init(cubePosition.x + cubeSize.x / 2, cubePosition.y + cubeSize.y / 2, cubePosition.z + cubeSize.z / 2),
+                });
+            } else collision.hit = false;
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+
+        rl.beginDrawing();
+        defer rl.endDrawing();
+        rl.clearBackground(rl.Color.ray_white);
+
+        {
+            camera.begin();
+            defer camera.end();
+
+            if (collision.hit) {
+                rl.drawCube(cubePosition, cubeSize.x, cubeSize.y, cubeSize.z, rl.Color.red);
+                rl.drawCubeWires(cubePosition, cubeSize.x, cubeSize.y, cubeSize.z, rl.Color.maroon);
+
+                rl.drawCubeWires(cubePosition, cubeSize.x + 0.2, cubeSize.y + 0.2, cubeSize.z + 0.2, rl.Color.green);
+            } else {
+                rl.drawCube(cubePosition, cubeSize.x, cubeSize.y, cubeSize.z, rl.Color.gray);
+                rl.drawCubeWires(cubePosition, cubeSize.x, cubeSize.y, cubeSize.z, rl.Color.dark_gray);
+            }
+
+            rl.drawRay(ray, rl.Color.maroon);
+            rl.drawGrid(10, 1);
+        }
+
+        rl.drawText("Try clicking on the box with your mouse!", 240, 10, 20, rl.Color.dark_gray);
+
+        if (collision.hit) {
+            rl.drawText("BOX SELECTED", @divTrunc((screenWidth - rl.measureText("BOX SELECTED", 30)), 2), screenHeight * 0.1, 30, rl.Color.green);
+        }
+
+        rl.drawText("Right click mouse to toggle camera controls", 10, 430, 10, rl.Color.gray);
+
+        rl.drawFPS(10, 10);
+    }
+}