add collision area example

examples/shapes/collision_area.zig

@@ -0,0 +1,114 @@
+const rl = @import("raylib");
+
+fn boxFmt(colliding: bool) rl.Color {
+    if (colliding) return rl.Color.red;
+    return rl.Color.black;
+}
+
+pub fn main() anyerror!void {
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const screenWidth = 800;
+    const screenHeight = 450;
+
+    rl.initWindow(screenWidth, screenHeight, "raylib-zig [shapes] example - collision area");
+    defer rl.closeWindow(); // Close window and OpenGL context
+
+    // Box A: Movingbox
+    var boxA = rl.Rectangle{ .x = 10, .y = (@as(f32, @floatFromInt(rl.getScreenHeight())) / 2.0) - 50, .width = 200, .height = 100 };
+    var boxASpeedX: f32 = 4;
+
+    // Box B: Mouse moved box
+    var boxB = rl.Rectangle{ .x = (@as(f32, @floatFromInt(rl.getScreenWidth())) / 2.0) - 30, .y = (@as(f32, @floatFromInt(rl.getScreenHeight())) / 2.0) - 30, .width = 60, .height = 60 };
+
+    var boxCollision = rl.Rectangle{ .x = 0, .y = 0, .width = 0, .height = 0 };
+
+    const screenUpperLimit = 40;
+
+    var pause = false;
+    var collision = false;
+
+    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
+        //----------------------------------------------------------------------------------
+        // Move box if not paused
+        if (!pause) {
+            boxA.x += boxASpeedX;
+        }
+
+        // Bounce box on x screen limits
+        if ((boxA.x + boxA.width) >= @as(f32, @floatFromInt(rl.getScreenWidth())) or (boxA.x <= 0)) {
+            boxASpeedX *= -1;
+        }
+
+        // Update player-controlled-box (box02)
+        boxB.x = @as(f32, @floatFromInt(rl.getMouseX())) - boxB.width / 2;
+        boxB.y = @as(f32, @floatFromInt(rl.getMouseY())) - boxB.height / 2;
+
+        // Make sure Box B does not go out of move area limits
+        if ((boxB.x + boxB.width) >= @as(f32, @floatFromInt(rl.getScreenWidth()))) {
+            boxB.x = @as(f32, @floatFromInt(rl.getScreenWidth())) - boxB.width;
+        } else if (boxB.x <= 0) {
+            boxB.x = 0;
+        }
+
+        if ((boxB.y + boxB.height) >= @as(f32, @floatFromInt(rl.getScreenHeight()))) {
+            boxB.y = @as(f32, @floatFromInt(rl.getScreenHeight())) - boxB.height;
+        } else if (boxB.y <= screenUpperLimit) {
+            boxB.y = screenUpperLimit;
+        }
+
+        // Check boxes collision
+        collision = rl.checkCollisionRecs(boxA, boxB);
+
+        // Get collision rectangle (only on collision)
+        if (collision) {
+            boxCollision = rl.getCollisionRec(boxA, boxB);
+        }
+
+        // Pause Box A movement
+        if (rl.isKeyPressed(.space)) {
+            pause = !pause;
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        rl.beginDrawing();
+        defer rl.endDrawing();
+
+        rl.drawRectangle(0, 0, screenWidth, screenUpperLimit, boxFmt(collision));
+
+        rl.drawRectangleRec(boxA, rl.Color.gold);
+        rl.drawRectangleRec(boxB, rl.Color.blue);
+
+        if (collision) {
+            // Draw collision area
+            rl.drawRectangleRec(boxCollision, rl.Color.lime);
+
+            // Draw collision message
+            rl.drawText(
+                "COLLISION!",
+                @divFloor(rl.getScreenWidth(), @as(i32, 2)) - @divFloor(rl.measureText("COLLISION!", 20), @as(i32, 2)),
+                screenUpperLimit / 2 - 10,
+                20,
+                rl.Color.black,
+            );
+
+            // Draw collision area
+            rl.drawText(rl.textFormat("Collision Area: %i", .{@as(i32, @intFromFloat(boxCollision.width * boxCollision.height))}), @divFloor(rl.getScreenWidth(), 2) - 100, screenUpperLimit + 10, 20, rl.Color.black);
+        }
+
+        // Draw help instructions
+        rl.drawText("Press SPACE to PAUSE/RESUME", 20, screenHeight - 35, 20, rl.Color.light_gray);
+
+        rl.drawFPS(10, 10);
+
+        rl.clearBackground(rl.Color.ray_white);
+        //----------------------------------------------------------------------------------
+    }
+}