Python OpenGLES

Cethric

I know there are already ports of the OpenGLES framework however I plan to make a binding which is specifically for the Pythonista 1.6+ builds
Project is here.
If anyone is interested in helping that would be great.
Currently I have an issue in the generation of glGenRenderbuffer. (I have already created a post however it was not transferred over to the new forum.)

omz

Quite honestly, I don't fully understand your code, and my experience with OpenGL is somewhat limited/outdated. But I've done some experimentation with GLKit myself, so the following code may still be helpful to some degree. It's basically the minimal setup for using GLKViewController. The demo just draws a single color that changes over time. Note that you'll need the latest beta for this (build 160023 from earlier today).

from objc_util import *
import time
import colorsys

GLKView = ObjCClass('GLKView')
GLKViewController = ObjCClass('GLKViewController')
UINavigationController = ObjCClass('UINavigationController')
UIBarButtonItem = ObjCClass('UIBarButtonItem')
EAGLContext = ObjCClass('EAGLContext')

glClearColor = c.glClearColor
glClearColor.restype = None
glClearColor.argtypes = [c_float, c_float, c_float, c_float]
glClear = c.glClear
glClear.restype = None
glClear.argtypes = [c_uint]
GL_COLOR_BUFFER_BIT = 0x00004000

def glkView_drawInRect_(_self, _cmd, view, rect):
	r, g, b = colorsys.hsv_to_rgb((time.time() * 0.1) % 1.0, 1, 1)
	glClearColor(r, g, b, 1.0)
	glClear(GL_COLOR_BUFFER_BIT)
MyGLViewDelegate = create_objc_class('MyGLViewDelegate', methods=[glkView_drawInRect_], protocols=['GLKViewDelegate'])

def dismiss(_self, _cmd):
	self = ObjCInstance(_self)
	self.view().delegate().release()
	self.view().setDelegate_(None)
	self.dismissViewControllerAnimated_completion_(True, None)
MyGLViewController = create_objc_class('MyGLViewController', GLKViewController, methods=[dismiss])

@on_main_thread
def main():
	context = EAGLContext.alloc().initWithAPI_(2).autorelease()
	glview = GLKView.alloc().initWithFrame_(((0, 0), (320, 320))).autorelease()
	delegate = MyGLViewDelegate.alloc().init()
	glview.setDelegate_(delegate)
	glview.setContext_(context)
	glview.setEnableSetNeedsDisplay_(False)
	glvc = MyGLViewController.alloc().initWithNibName_bundle_(None, None).autorelease()
	glvc.setTitle_('GLKit Demo')
	glvc.setView_(glview)
	done_b = UIBarButtonItem.alloc().initWithTitle_style_target_action_('Done', 2, glvc, 'dismiss').autorelease()
	glvc.navigationItem().setRightBarButtonItem_(done_b)
	nav = UINavigationController.alloc().initWithRootViewController_(glvc)
	rootvc = UIApplication.sharedApplication().keyWindow().rootViewController()
	rootvc.presentModalViewController_animated_(nav, True)
	nav.release()

main()

Cethric

Thanks @omz for the response, it seems to work much better than what I had.
I am in the process of intergrating it now, would it be possible to add the GLViewController into the pythonista ui.View? so that it would be possible to use Pythonista's view system instead of having to reference through ctypes to UIKit?

I will push an updated version of the repo soon
Thanks again

JonB

you should be able to add a glkview as a subview of a ui.View. You might even consider a wrapper class which does that for you, creating the glview instance and storing it as an instance variable, setting the frame/bounds/flex correctly, etc.

as the simplest approach,

wrapper= ui.View(frame=(0,0,320,320))
ObjCInstance(wrapper).addSubview_(glview)

Cethric

@JonB wouldn't doing that ignore the GLKViewController? and if not how would I impliment it? My current code which is a rewrite of @omz's MKMapView script does not seem to work correctly.

JonB

this worked (after glvc.setview...)

    v = ui.View(frame=(0,0,600,600))
    vo = ObjCInstance(v)    
    v.present('sheet') #must be presented for nextResponder to work
    vo.nextResponder().addChildViewController_(glvc)
    vo.addSubview_(glview)

not sure this can be represented after the view is closed, might be worth hanging onto glvc, so you can add it after v is re-presented.

Cethric

Thanks @JonB it seems to be working now

JonB

incidentally, when experimenting with this, i often got "The view is already being presented or an animation is running"..... @omz what does pythonista use to determine whether a view is already being presented (so we can make sure to clean it up before closing?)

omz

@JonB It basically checks if nextResponder is a UIViewController. The ui module creates view controllers for presentation automatically, and if a view already has an associated view controller, it usually means that it's currently being presented...

Cethric

How do I properly setup a GLKViewController delegate?
My current code does not seem to work at all

def glkViewControllerUpdate_(_controller):
    print "Update", _controller

GLKViewControllerDelegate_Class = create_objc_class('GLKViewControllerDelegate_Class', methods=[glkViewControllerUpdate_], protocols='GLKViewControllerDelegate')
    
def GLKViewControllerDelegate():
    return GLKViewControllerDelegate_Class.alloc().init()

which is called in the GLKView class

self.vc = GKLViewController("Test GLES", self.glview)
self.vcd = GLKViewControllerDelegate()
self.vc.delegate = self.vcd

GKLViewController is just a wrapper for the ctypes function

omz

@Cethric Your glkViewControllerUpdate_ method needs to have three parameters, e.g.

def glkViewControllerUpdate_(_self, _cmd, _controller):
    ...

(the actual names of the parameters don't really matter, I tend to use underscores to indicate that these are pointers and not actual objects...)

To actually set the delegate, use the setDelegate_ method, like this:

self.vc.setDelegate_(self.vcd)

Cethric

@omz Thank you so much it seems to work now
Hopefully one last question, the 3 parameters only return pointers so what would be the 'best' solution to get the GLKViewController.framesPerSecond variable?

omz

Wrap the _controller parameter in an ObjCInstance:

def glkViewControllerUpdate_(_self, _cmd, _controller):
    controller = ObjCInstance(_controller)
    fps = controller.framesPerSecond()
    dt = controller.timeSinceLastUpdate()
    # ...

Cethric

@omz thanks again it works now

Cethric

glCreateShader always fails but I don't know why

def loadShader(source, glsl_type):
    shader = GLuint()
    compiled = GLint()
    # Create the shader object
    shader = glCreateShader(glsl_type)
    if(shader == 0):
        print "Failed to create shader"
        return 0;
    # Load the shader source
    glShaderSource(shader, 1, shaderSrc, 0)
    # Compile the shader
    glCompileShader(shader)
    # Check the compile status
    
    glGetShaderiv(shader, GL_COMPILE_STATUS, ctypes.byref(compiled))
    if(not compiled):
        infoLen = GLint(0)
        glGetShaderiv(shader, GL_INFO_LOG_LENGTH, ctypes.byref(infoLen))
        if(infoLen > 1):
            infoLog = (ctypes.c_char * infoLen)()
            glGetShaderInfoLog(shader, infoLen, 0, infoLog);
            print("Error compiling shader:\n%s\n" % infoLog);
        glDeleteShader(shader);
        return 0;
    return shader;

How glCreateShader is referenced

try:
    glCreateShader = c.glCreateShader
    glCreateShader.restype = GLuint
    glCreateShader.argtypes = [GLenum]
except AttributeError as e:
    if DEBUG:
        print 'could not load the function'
        print e

Called in the setup process as

class Renderer(Util.RenderCycler):
    def __init__(self):
        Util.RenderCycler.__init__(self)
        self.r, self.g, self.b = colorsys.hsv_to_rgb((time.time() * 0.1) % 1.0, 0.1, 1)
    
    def setup(self, context):
        if (EAGL.setCurrentContext(context)):
            glClearColor(1, 1, 1, 1.0)
            s = Util.loadShader("void main() {}", GLenum(GL_FRAGMENT_SHADER))
            print s
        else:
            print "Could not Setup OpenGLES"
            
    def update(self, dt):
        self.r, self.g, self.b = colorsys.hsv_to_rgb((time.time() * 0.1) % 1.0, 1.0, 1)
    
    def render(self, context):
        if (EAGL.setCurrentContext(context)):
            glClearColor(self.r, self.g, self.b, 1.0)
            glClear(GL_COLOR_BUFFER_BIT)

Cethric

Anyone got an idea? @omz @JonB
Is it potentially because I am calling it from a custom setup event and not on a onDraw or onUpdate event?

EDIT: Never mind I answered my own question... It was because I was calling setup at the wrong time

Cethric

@omz @JonB is there a way to access the GLKit Math classes? (ie. GLKMatrix4)

JonB

you will need to find the structure definitions, and create your own ctypes structs.

for instance http://developer.limneos.net/?framework=GLKit.framework&header=GLKit-Structs.h

You will need to create classes that extend Structure, and implement the _fields_ appropriately. (note some of these are unions... you can either onherit from Union, or just pick which way you'd rather refer to the fields, and just use a Structure). these mostly sppesr to be simple arrays of 16 floats for example, so you could slso probably do GLKMatrix4=c_float*16 for example.

All of the GLKMatrix4Makexxxxxxxx functions are inlined, so you have to make your own constructors. For the most basic stule, you just define the 16 coefficients directly. zfor the more complicated versions, https://searchcode.com/codesearch/view/70695332/ may have some ideas on what these should look like, so you can roll your own.

Cethric

Will look into it, thanks for the response

Cethric

Working on an example file main.py to test shaders and rendering. However I cannot get the view to show a cube I think the issue is with the MVP however I do not know at what point I am going wrong, can someone please look at it and let me know
For simplicity I am using the euclid.py math library.

Thanks in advanced.