Is it possible to access OpenGL ES on iOS from RoboVM without using LibGDX? If so, are there any useful references?
The only thing I can find is this super-simple demo from over 2 years ago: http://robovm.com/ios-opengles-in-java-on-robovm/
But it doesn't provide any functions besides glClearColor and glClear.
The Apple GLKit framework seems to be implemented, though. I just can't find all the actual glWhatever(...) functions...
Yes, it is possible. You need two things for this: 1. Access to the OpenGL ES functions (like glClear(...), etc.) and 2. a UIView in your app that can draw the GL image.
Turns out the second point is very easy. You can either use a GLKView (requires iOS 5.0) or a CAEAGLLayer (requires iOS 2.0) if you're feeling nostalgic. For both, there are tons of tutorials online on how to use them in Objective-C, which can readily be translated to RoboVM. So, I won't spend too much time on this point here.
Access to the OpenGL ES functions is a little more difficult, as RoboVM doesn't ship with the definitions file out of the box. So, we'll have to build our own using Bro. Turns out, once you wrap your head around how Bro handles C-strings, variable pointers, IntBuffers and such (which is actually quite beautiful!), it's really pretty straight forward. The super-simple demo I linked to in the original question is the right starting point.
In the interest of brevity, let me post here just a very abridged version of the file I wrote to illustrate the way the different data types can be handled:
import java.nio.Buffer;
import java.nio.IntBuffer;
import org.robovm.rt.bro.Bro;
import org.robovm.rt.bro.Struct;
import org.robovm.rt.bro.annotation.Bridge;
import org.robovm.rt.bro.annotation.Library;
import org.robovm.rt.bro.ptr.BytePtr;
import org.robovm.rt.bro.ptr.BytePtr.BytePtrPtr;
import org.robovm.rt.bro.ptr.IntPtr;
#Library("OpenGLES")
public class GLES20 {
public static final int GL_DEPTH_BUFFER_BIT = 0x00000100;
public static final int GL_STENCIL_BUFFER_BIT = 0x00000400;
public static final int GL_COLOR_BUFFER_BIT = 0x00004000;
public static final int GL_FALSE = 0;
public static final int GL_TRUE = 1;
private static final int MAX_INFO_LOG_LENGTH = 10*1024;
private static final ThreadLocal<IntPtr> SINGLE_VALUE =
new ThreadLocal<IntPtr>() {
#Override
protected IntPtr initialValue() {
return Struct.allocate(IntPtr.class, 1);
}
};
private static final ThreadLocal<BytePtr> INFO_LOG =
new ThreadLocal<BytePtr>() {
#Override
protected BytePtr initialValue() {
return Struct.allocate(BytePtr.class, MAX_INFO_LOG_LENGTH);
}
};
static {
Bro.bind(GLES20.class);
}
#Bridge
public static native void glClearColor(float red, float green, float blue, float alpha);
#Bridge
public static native void glClear(int mask);
#Bridge
public static native void glGetIntegerv(int pname, IntPtr params);
// DO NOT CALL THE NEXT METHOD WITH A pname THAT RETURNS MORE THAN ONE VALUE!!!
public static int glGetIntegerv(int pname) {
IntPtr params = SINGLE_VALUE.get();
glGetIntegerv(pname, params);
return params.get();
}
#Bridge
private static native int glGetUniformLocation(int program, BytePtr name);
public static int glGetUniformLocation(int program, String name) {
return glGetUniformLocation(program, BytePtr.toBytePtrAsciiZ(name));
}
#Bridge
public static native int glGenFramebuffers(int n, IntPtr framebuffers);
public static int glGenFramebuffer() {
IntPtr framebuffers = SINGLE_VALUE.get();
glGenFramebuffers(1, framebuffers);
return framebuffers.get();
}
#Bridge
private static native void glShaderSource(int shader, int count, BytePtrPtr string, IntPtr length);
public static void glShaderSource(int shader, String code) {
glShaderSource(shader, 1, new BytePtrPtr().set(BytePtr.toBytePtrAsciiZ(code)), null);
}
#Bridge
private static native void glGetShaderInfoLog(int shader, int maxLength, IntPtr length, BytePtr infoLog);
public static String glGetShaderInfoLog(int shader) {
BytePtr infoLog = INFO_LOG.get();
glGetShaderInfoLog(shader, MAX_INFO_LOG_LENGTH, null, infoLog);
return infoLog.toStringAsciiZ();
}
#Bridge
public static native void glGetShaderPrecisionFormat(int shaderType, int precisionType, IntBuffer range, IntBuffer precision);
#Bridge
public static native void glTexImage2D(int target, int level, int internalformat, int width, int height, int border, int format, int type, IntBuffer data);
#Bridge
private static native void glVertexAttribPointer(int index, int size, int type, int normalized, int stride, Buffer pointer);
public static void glVertexAttribPointer(int index, int size, int type, boolean normalized, int stride, Buffer pointer) {
glVertexAttribPointer(index, size, type, normalized ? GL_TRUE : GL_FALSE, stride, pointer);
}
}
Note how most methods are exposed via just trivial #Bridge-annotated native definitions, but for some it's convenient to define a wrapper method in Java that converts a String to a *char or unpacks a result from an IntPtr for example.
I didn't post my whole library file, since it is still very incomplete and it'll just make it harder to find the examples of how different parameter types are handled.
To save yourself some work, you can copy the GL constant definitions from libGDX's GL20.java. And the OpenGL ES docs are a great reference for the calling signature of the methods (the data types GLenum and GLbitfield correspond to a Java int).
You can then call the gl-methods statically by prepending GLES20. (just like on Android), e.g.:
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
Turns out Bro is so smart that you don't even need to include the <framework>OpenGLES</framework> tag in robovm.xml any more, like you would with libGDX.
And - What do you know? - my app starts about 3 times as quickly as it did when it was still using libGDX. And it fixed another issue I had (see LibGDX displays black screen while app is paused but still visible (e.g. during in-app purchase password dialog) on iOS). "Yay!" for getting rid of unnecessary baggage.
The one thing that makes life a little annoying is that if you mess up the call signature of a method or the memory allocation, your app will simply crash with a very unhelpful "Terminated due to signal 11" message in the IDE-console that contains no information about where the app died.
Related
From here, we know if malloc_logger global function is defined, it will be called whenever there is a malloc or free operation. I want to use it to record memory allocations in my app like this:
typedef void(malloc_logger_t)(uint32_t type,
uintptr_t arg1,
uintptr_t arg2,
uintptr_t arg3,
uintptr_t result,
uint32_t num_hot_frames_to_skip);
extern malloc_logger_t *malloc_logger;
void my_malloc_stack_logger(uint32_t type, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3, uintptr_t result, uint32_t num_hot_frames_to_skip);
malloc_logger = my_malloc_stack_logger;
void my_malloc_stack_logger(uint32_t type, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3, uintptr_t result, uint32_t num_hot_frames_to_skip)
{
// do my work
}
In my_malloc_stack_logger, I can directly get the allocated size and address. But how about object types? I want to record the class name if it is an NSObject instance. Is it possible to get this information?
After playing around with the hook, it looks like what you want to achieve is not quite possible.
First problem here is that if you try to read a class name from within this function (by calling any of object_getClassName, class_getName
or NSStringFromClass), this action on its own tends to trigger new allocations. That apparently happens because some Cocoa classes load lazily. I noticed however that when requesting all classes with objc_getClassList it makes a lot of preliminary allocations that helps to avoid them later on. So my idea is to cache all class names before subscribing to the allocations hook and refer to the cached values when needed. For the storage I used Apple's CFMutableDictionary:
CFMutableDictionaryRef objc_class_records;
void refresh_objc_class_list(void) {
pthread_mutex_lock(&objc_class_records_mutex);
if (objc_class_records) {
CFRelease(objc_class_records);
}
objc_class_records = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, NULL, &kCFTypeDictionaryValueCallBacks);
// The buffer needs to accomodate at least 26665 instances
static const unsigned buffer_length = 100000;
Class registered_classes[buffer_length];
objc_getClassList(registered_classes, buffer_length);
for (unsigned i = 0; i < buffer_length; ++i) {
if (!registered_classes[i]) {
break;
}
const Class class = registered_classes[i];
const CFStringRef class_name = CFStringCreateWithCString(kCFAllocatorDefault, class_getName(class), kCFStringEncodingUTF8);
CFDictionarySetValue(objc_class_records, class, class_name);
CFRelease(class_name);
}
}
Be advised that you don't want to have it called when the malloc logger is enabled (especially from within the hook itself).
Now you need to obtain a Class instance from the Objective-C objects. Depending on the type of allocation, the pointer argument goes to fifth or third parameter:
void my_malloc_logger(uint32_t type, uintptr_t param0, uintptr_t param1, uintptr_t param2,
uintptr_t param3, uint32_t frames_to_skip) {
void *ptr = NULL;
unsigned size = 0;
switch (type) {
case MALLOC_OP_MALLOC:
case MALLOC_OP_CALLOC:
ptr = (void *)param3;
size = (unsigned)param1;
break;
case MALLOC_OP_REALLOC:
ptr = (void *)param3;
size = (unsigned)param2;
break;
case MALLOC_OP_FREE:
ptr = (void *)param1;
break;
}
id objc_ptr = (id)ptr;
Class objc_class = object_getClass(objc_ptr);
if (!objc_class) {
return;
}
const CFStringRef class_name;
const bool found = CFDictionaryGetValueIfPresent(objc_class_records, objc_class, (const void **)&class_name);
if (found) {
const static unsigned name_max_length = 256;
char c_class_name[name_max_length];
if (CFStringGetCString(class_name, c_class_name, name_max_length, kCFStringEncodingUTF8)) {
const char *alloc_name = alloc_type_name(type);
nomalloc_printf_sync("%7s: Pointer: %p; Size: %u; Obj-C class: \"%s\"\n", alloc_name, objc_ptr, size, c_class_name);
}
}
}
And now why it won't work as expected:
object_getClass is not able to tell whether a pointer is an object of Cococa classes at the time of allocation (it will find the class, however, when the object is already allocated, e.g. before deallocation). Thus, the following code:
[NSObject new];
Will produce output similar to this:
CALLOC: Pointer: 0x600000600080; Size: 16
FREE: Pointer: 0x600000600080; Size: 0; Obj-C class: "NSObject"
Most of the standard Cocoa classes are in fact so-called Class Clusters and under the hood the actual allocation happens for an instance of a private class (which is not always recognisable by its public interface), thus this information is incomplete and sometimes misleading.
There are also many other factors which need to be taken into account (which i didn't cover here because it's beyond the question asked): the way you output data to standard output should not cause allocation by itself; the logging needs synchronisation since allocation happens a lot from any number of threads; if you want to enable/disable recording the Objective-C classes (or update the cache occasionally) access to the storage also needs to be synchronised.
Having that said if you are satisfied with what can be done with it, feel free to refer to the repository I made where this approach is already implemented in a form of a static library.
I've successfully wrapped a C DLL library using JNA.
As I'm not the owner of the C development part, I would like to hide
some parameters of a C function that I've wrapped on java side.
To be more precise my java code is as follows :
public interface IJNALibrary extends Library {
// INIT FUNCTION
public int initFunction(int firstValue, int secondValue, int thirdValue);
}
On the C side I have in the *.h file :
extern "C" CSAMPLE_API int initFunction (
unsigned firstValue,
unsigned secondValue,
unsigned thirdValue);
My purpose is to directly set secondValue and thirdValue parameters to 1 and thus hide those parameters to the java API user.
I don't want the user to know that he could change the values of those parameters.
In fact I would like to have something like :
public interface IJNALibrary extends Library {
// INIT FUNCTION
public int initFunction(int firstValue);
}
and initFunction(int firstValue) calls initFunction(int firstValue, int secondValue, int thirdValue) from the C DLL part.
But this has to be done inside the java Wrapper and not from the code which calls the java Wrapper.
I'm afraid that It cannot be possible, is it?
Unless I create another C DLL (with public int initFunction(int firstValue) function) which calls the first C DLL(which embed initFunction(int firstValue, int secondValue, int thirdValue).But I would rather do it on the java side in order not to have manage 2 C DLLs.
See also below the Sample.java file which calls the mapped method defined in IJNALibrary interface.
public class Sample {
static IJNALibrary IJNAFunctions;
public static void main(String[] args) throws IOException {
System.setProperty("jna.library.path", "./librayPath");
// LOADING LIBRARY
IJNAFunctions = (IJNALibrary) Native.load("c", IJNALibrary.class);
int firstValue = 1;
int secondValue = 2;
int thirdValue = 3;
int initReturn = IJNAFunctions.initFunction(firstValue, secondValue, thirdValue);
}
}
Thanx for your help.
It depends on what you want to archive. If you want to make it easier for users to call the init, this is an option (demonstrated using gethostname from libc), which uses a Java 8 feature, which allows adding default methods to interfaces:
public class TestDefaultMethod {
public static interface LibC extends Library {
LibC INSTANCE = Native.load("c", LibC.class);
// Original binding of method
int gethostname(byte[] name, int len);
// Helper method to make it easier to call gethostname
default String gethostname() {
byte[] result = new byte[255];
LibC.INSTANCE.gethostname(result, result.length);
return Native.toString(result);
}
}
public static void main(String[] args) {
// Usage
System.out.println(LibC.INSTANCE.gethostname());
}
}
Java developers normally don't arrays to functions, which fill them and a java developer would never pass the length of the array in a separate parameter. These are artifacts of the C nature of the function. In the wrapped function an array is allocated, the native call done and the array then unwrapped. All the ugly C specialties are hidden in the default method.
If you don't want to expose the method on java at all (be warned, if your users can access the JNA library, they can circumvent your protections!), you can use a function pointer directly:
public class TestDefaultMethod {
public static interface LibC extends Library {
NativeLibrary libc = NativeLibrary.getInstance("c");
LibC INSTANCE = Native.load("c", LibC.class);
default String gethostname() {
byte[] result = new byte[255];
libc.getFunction("gethostname").invokeInt(new Object[] {result, result.length});
return Native.toString(result);
}
}
public static void main(String[] args) {
System.out.println(LibC.INSTANCE.gethostname());
}
}
Same idea as above, the default method will hide the ugly parts. In this case though the function is not accessed through the managed INSTANCE, but access through the function pointer directly.
public interface Kernel32 extends StdCallLibrary {
int GetComputerNameW(Memory lpBuffer, IntByReference lpnSize);
}
public class Kernel32Test {
private static final String THIS_PC_NAME = "tiangao-160";
private static Kernel32 kernel32;
#BeforeClass
public static void setUp() {
System.setProperty("jna.encoding", "GBK");
kernel32 = (Kernel32) Native.loadLibrary("kernel32", Kernel32.class);
}
#AfterClass
public static void tearDown() {
System.setProperty("jna.encoding", null);
}
#Test
public void testGetComputerNameW() {
final Memory lpBuffer = new Memory(1024);
final IntByReference lpnSize = new IntByReference();
final int result = kernel32.GetComputerNameW(lpBuffer, lpnSize);
if (result != 0) {
throw new IllegalStateException(
"calling 'GetComputerNameW(lpBuffer, lpnSize)'failed，errorcode：" + result);
}
final int bufferSize = lpnSize.getValue();
System.out.println("value of 'lpnSize'：" + bufferSize);
Assert.assertEquals(THIS_PC_NAME.getBytes().length + 1, bufferSize);
final String name = lpBuffer.getString(0);
System.out.println("value of 'lpBuffer'：" + name);
Assert.assertEquals(THIS_PC_NAME, name);
}
}
The offical instructions says use byte[]、char[]、Memory or NIO Buffer for mapping char pointer in c native function.But I tried all of above, and String、WString、StringArrays、class extends PointType etc, all of them are no use.
Out parameter 'lpnSize' can return the corret buffer size，but 'lpBuffer' return 'x>'(i think it's random memory) or nothing no matter I mapping any java type.If i wrote someting to the 'lpBuffer' memory first, it would read the same things after calling native function.
How can I solve the problem?
You need to use Pointer.getString(0, true) to extract the unicode string returned by GetComputerNameW.
EDIT
You'll also need to call GetComputerNameW again with the length parameter initialized before the function will fill in the result. Either pass back the same IntByReference to a second call, or initialize the IntByReference to the size of your Memory buffer to have the buffer written to in the first call.
Bullet has an implementation of the btIDebugDraw interface in older OpenGL which is used to draw the physics world for debugging. The interface is like this :
class GLDebugDrawer : public btIDebugDraw
{
int m_debugMode;
public:
GLDebugDrawer();
virtual ~GLDebugDrawer();
virtual void drawLine(const btVector3& from,const btVector3& to,const btVector3& fromColor, const btVector3& toColor);
virtual void drawLine(const btVector3& from,const btVector3& to,const btVector3& color);
virtual void drawSphere (const btVector3& p, btScalar radius, const btVector3& color);
virtual void drawTriangle(const btVector3& a,const btVector3& b,const btVector3& c,const btVector3& color,btScalar alpha);
virtual void drawContactPoint(const btVector3& PointOnB,const btVector3& normalOnB,btScalar distance,int lifeTime,const btVector3& color);
virtual void reportErrorWarning(const char* warningString);
virtual void draw3dText(const btVector3& location,const char* textString);
virtual void setDebugMode(int debugMode);
virtual int getDebugMode() const { return m_debugMode;}
};
The OpenGL 1.1 implementation works in immediate mode sending vertices down to the GPU at every function call. eg. here is drawLine()
void GLDebugDrawer::drawLine(const btVector3& from,const btVector3& to,const btVector3& fromColor, const btVector3& toColor)
{
glBegin(GL_LINES);
glColor3f(fromColor.getX(), fromColor.getY(), fromColor.getZ());
glVertex3d(from.getX(), from.getY(), from.getZ());
glColor3f(toColor.getX(), toColor.getY(), toColor.getZ());
glVertex3d(to.getX(), to.getY(), to.getZ());
glEnd();
}
To convert this into OpenGL 4.0, I am thinking of using a Vertex Array Object defined as a member of this class, say mVAO and the VBOs will also be members. I will setup the VAO in the ctor of GLDebugDrawer and then generate and send vertices to the VBO as well as render it within drawLine()
drawLine()
{
// Update buffers
// Bind and render the buffer
}
But since I ll be sending vertices everytime drawLine() gets called, it seems I am not using the power of VAO but instead simulating immediate mode rather badly!
What would be a better way to implement a line drawing function in this interface whose vertices can change in every call ?
I want to use this code in my android app later to check my physics, so I am rewriting the interface in OpenGL 4.0 which I assume will be easier to convert to openGLES 2.0 .
I was thinking of recording the vertices in a vector at every drawLine() call and then updating the VBO after all of Bullet's calls to the btIDebugDraw functions are complete. Then I would not need to send pairs of vertices intermittently to the GPU as Bullet calls the btIDebugDraw functions.
I have got some information here about managing vertex data so far :
http://developer.apple.com/library/ios/#documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/TechniquesforWorkingwithVertexData/TechniquesforWorkingwithVertexData.html
Do not immediately draw on drawLine(). :)
Instead push the Vertices/Colors into a buffer in Host/RAM.
After the call to dynamicsWorld->debugDrawWorld(), you know that your DebugDrawer got all the lines for the frame, so you can do:
update the VBOs once
glDraw ...
clear the Host Buffer
This might be a really stupid question but what happens to data that is returned from a method? For example, if I have a method that adds two numbers and I tell it to return the sum, how would I access that information from the place where the method was called?
Assuming your question is related with java.
You could assign the whole method to a new variable.
public class Test {
public static void main(String args[]){
int value1=2;
int value2=5;
int sum=sum(value1,value2);
System.out.println("The sum is :"+ sum);
}
public static int sum(int value1,int value2){
return value1+value2;
}
}
What is actually happening, is that the method signature sum(value1,value2) holds the result of the 2 numbers summation. There is also another way of writing the code inside the method but the result will be the same.
For example:
public class Test {
public static void main(String args[]){
int sum=sum(2,5);
System.out.println("The sum is :"+ sum);
}
public static int sum(int value1,int value2){
int sum=value1+value2;
return sum;
}
}
P.S. You could try to use the above samples directly. They will compile and run.
In most languages, you access the result of a function by putting the function call on the right hand side of an assignment expression.
For example, in Python, you can assign the result of calling the built-in len function on a list to a variable called x by doing the following:
x = len([1, 2, 3])