How to Use Vulkan for GPU Acceleration in Kotlin Android Apps

Modern Android applications are expected to deliver smooth animations, rich visuals, and real-time graphical effects. However, executing heavy graphical operations on the CPU can quickly lead to performance bottlenecks, increased battery consumption, and poor user experience. For a broader look at tools that can elevate your Android development workflow, check out our guide on 10 Android libraries you really need.

Earlier, Android developers relied on RenderScript for GPU-accelerated workloads. With RenderScript now deprecated, Vulkan has emerged as the most powerful and future-ready alternative for high-performance graphics and compute operations on Android.

In this blog, we'll explore how to utilize GPU capabilities using Vulkan in Kotlin-based Android apps to efficiently handle intensive graphical workloads and unlock next-level performance.

Why Use Vulkan for Android GPU Acceleration?

Vulkan is a low-level, cross-platform graphics and compute API designed for maximum performance and efficiency. Unlike OpenGL ES, Vulkan gives developers explicit control over GPU resources, enabling:

• Lower CPU overhead
• Predictable performance
• Better multi-threading
• Fine-grained memory management

This makes Vulkan ideal for image processing, real-time effects, AR/VR, game development, and compute-heavy Android applications.

What Are the Prerequisites to Use Vulkan in Kotlin Android Apps?

Before getting started, you should have:

• Basic knowledge of Android app development using Kotlin
• Familiarity with Android Studio
• A general understanding of GPU programming concepts (helpful but not mandatory)
• A physical Android device with Vulkan support (recommended for testing)

Step 1: Setting Up the Android Project

1. Open Android Studio
2. Create a new project using the Empty Activity template
3. Name your project appropriately (e.g., VulkanGraphicsDemo)
4. Select a minimum API level based on your target devices
5. Click Finish

Step 2: Enabling Vulkan Support in Android

Vulkan requires access to native GPU capabilities, which is handled through the Android NDK.

Configure build.gradle

Open your app-level build.gradle file and add the following under the android block:

android {
    defaultConfig {
        ndk {
            version "your_ndk_version"
        }
    }
}

Replace "your_ndk_version" with the NDK version installed on your system.

Once added, sync your project with Gradle.

Step 3: Initializing Vulkan in Kotlin

Create a helper class to manage Vulkan initialization and lifecycle.

1. Create a new Kotlin class called VulkanHelper in your project.
2. Open the VulkanHelper class and define the necessary methods for Vulkan initialization.

Create VulkanHelper.kt

import android.content.Context
import android.graphics.Bitmap
import android.util.Log
import org.lwjgl.PointerBuffer
import org.lwjgl.system.MemoryStack
import org.lwjgl.vulkan.*

class VulkanHelper(private val context: Context) {
    private lateinit var instance: VkInstance
    private lateinit var physicalDevice: VkPhysicalDevice
    private lateinit var device: VkDevice
    private lateinit var queue: VkQueue

    fun initializeVulkan() {
        createInstance()
        selectPhysicalDevice()
        createLogicalDevice()
        getDeviceQueue()
    }

    private fun createInstance() {
        val appInfo = VkApplicationInfo.calloc()
            .sType(VK11.VK_STRUCTURE_TYPE_APPLICATION_INFO)
            .pApplicationName(context.packageName)
            .pEngineName("MyEngine")
            .apiVersion(VK11.VK_API_VERSION_1_1)

        val createInfo = VkInstanceCreateInfo.calloc()
            .sType(VK11.VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO)
            .pNext(VK11.VK_NULL_HANDLE)
            .pApplicationInfo(appInfo)

        val pInstance = MemoryStack.stackPush().use {
            val pp = it.mallocPointer(1)
            if (VK11.vkCreateInstance(createInfo, null, pp) != VK11.VK_SUCCESS) {
                throw RuntimeException("Failed to create Vulkan instance")
            }
            pp[0]
        }

        instance = VkInstance(pInstance, createInfo)

        appInfo.free()
        createInfo.free()
    }

    private fun selectPhysicalDevice() {
        // Select the appropriate physical device based on your requirements
        // ...

        physicalDevice = // Selected physical device
    }

    private fun createLogicalDevice() {
        // Create a logical device using the selected physical device
        // ...

        device = // Created logical device
    }

    private fun getDeviceQueue() {
        val queueFamilyProperties = VkQueueFamilyProperties.malloc(1)
        VK11.vkGetPhysicalDeviceQueueFamilyProperties(physicalDevice, queueFamilyProperties)

        val pQueue = MemoryStack.stackPush().use {
            val pp = it.mallocPointer(1)
            VK11.vkGetDeviceQueue(device, 0, 0, pp)
            pp[0]
        }

        queue = VkQueue(pQueue, device)
    }

    fun performGraphicalOperation(input: Bitmap): Bitmap {
        // Perform your heavy graphical operation using Vulkan
        // ...
        return input 
        // Placeholder, replace with the processed image
    }

    fun cleanup() {
        // Cleanup Vulkan resources
        // ...
    }
}

Note: This code is illustrative and not production-ready. Proper error handling, threading, and synchronization are essential for real-world apps.

Step 4: Integrating Vulkan into Your Android Activity

1. Open the activity or fragment where GPU-accelerated graphical operations are required.
2. Create an instance of the VulkanHelper class within the activity or fragment.
3. Call the initializeVulkan() method during the lifecycle (such as in onCreate) to set up Vulkan.
4. Use the performGraphicalOperation() method to execute heavy graphical or compute-intensive tasks on the GPU.
5. Call the cleanup() method when the activity or fragment is destroyed to safely release Vulkan resources.

class MainActivity : AppCompatActivity() {
    private lateinit var vulkanHelper: VulkanHelper

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        vulkanHelper = VulkanHelper(applicationContext)
        vulkanHelper.initializeVulkan()

        val inputBitmap: Bitmap = // Obtain or create the input Bitmap
        val outputBitmap = vulkanHelper.performGraphicalOperation(inputBitmap)

        // Use the outputBitmap for display or further processing
    }

    override fun onDestroy() {
        super.onDestroy()
        vulkanHelper.cleanup()
    }
}

For best performance, run Vulkan operations on a background thread to avoid blocking the UI.

What are the Capabilities of Vulkan on Android

1. High-Performance 3D Rendering

Vulkan excels at rendering complex 3D scenes with minimal CPU overhead, supporting advanced shaders, textures, and lighting models.

2. GPU Compute Shaders

Ideal for image processing, AI workloads, physics simulations, and real-time effects using massively parallel GPU execution.

3. Multi-Threaded Rendering

Vulkan allows command buffers to be generated across multiple CPU threads, significantly improving rendering performance.

4. Explicit Memory Management

Developers have fine-grained control over GPU memory allocation, helping optimize performance and reduce memory waste.

5. Low-Level GPU Control

Explicit synchronization, pipeline management, and command submission enable predictable, optimized GPU behavior.

Conclusion

With RenderScript deprecated, Vulkan is the go-to solution for GPU acceleration in modern Android apps. By integrating Vulkan into Kotlin-based Android projects, developers can unlock high-performance graphics, efficient compute operations, and smoother user experiences.

While Vulkan introduces complexity, the performance benefits are well worth the effort - especially for graphics-heavy, compute-intensive, or real-time applications.

At Appxiom, we believe leveraging cutting-edge technologies like Vulkan empowers developers to build faster, more immersive Android applications.