from OpenGL.GL import *
from OpenGL.arrays import vbo
from .. GLGraphicsItem import GLGraphicsItem
from .. import shaders
from ... import QtGui
import numpy as np

__all__ = ['GLScatterPlotItem']

class GLScatterPlotItem(GLGraphicsItem):
    """Draws points at a list of 3D positions."""
    
    def __init__(self, **kwds):
        GLGraphicsItem.__init__(self)
        glopts = kwds.pop('glOptions', 'additive')
        self.setGLOptions(glopts)
        self.pos = []
        self.size = 10
        self.color = [1.0,1.0,1.0,0.5]
        self.pxMode = True
        #self.vbo = {}      ## VBO does not appear to improve performance very much.
        self.setData(**kwds)
    
    def setData(self, **kwds):
        """
        Update the data displayed by this item. All arguments are optional; 
        for example it is allowed to update spot positions while leaving 
        colors unchanged, etc.
        
        ====================  ==================================================
        **Arguments:**
        pos                   (N,3) array of floats specifying point locations.
        color                 (N,4) array of floats (0.0-1.0) specifying
                              spot colors OR a tuple of floats specifying
                              a single color for all spots.
        size                  (N,) array of floats specifying spot sizes or 
                              a single value to apply to all spots.
        pxMode                If True, spot sizes are expressed in pixels. 
                              Otherwise, they are expressed in item coordinates.
        ====================  ==================================================
        """
        args = ['pos', 'color', 'size', 'pxMode']
        for k in kwds.keys():
            if k not in args:
                raise Exception('Invalid keyword argument: %s (allowed arguments are %s)' % (k, str(args)))
            
        args.remove('pxMode')
        for arg in args:
            if arg in kwds:
                setattr(self, arg, kwds[arg])
                #self.vbo.pop(arg, None)
                
        self.pxMode = kwds.get('pxMode', self.pxMode)
        self.update()

    def initializeGL(self):
        
        ## Generate texture for rendering points
        w = 64
        def fn(x,y):
            r = ((x-w/2.)**2 + (y-w/2.)**2) ** 0.5
            return 255 * (w/2. - np.clip(r, w/2.-1.0, w/2.))
        pData = np.empty((w, w, 4))
        pData[:] = 255
        pData[:,:,3] = np.fromfunction(fn, pData.shape[:2])
        #print pData.shape, pData.min(), pData.max()
        pData = pData.astype(np.ubyte)
        
        if getattr(self, "pointTexture", None) is None:
            self.pointTexture = glGenTextures(1)
        glActiveTexture(GL_TEXTURE0)
        glEnable(GL_TEXTURE_2D)
        glBindTexture(GL_TEXTURE_2D, self.pointTexture)
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, pData.shape[0], pData.shape[1], 0, GL_RGBA, GL_UNSIGNED_BYTE, pData)
        
        self.shader = shaders.getShaderProgram('pointSprite')
        
    #def getVBO(self, name):
        #if name not in self.vbo:
            #self.vbo[name] = vbo.VBO(getattr(self, name).astype('f'))
        #return self.vbo[name]
        
    #def setupGLState(self):
        #"""Prepare OpenGL state for drawing. This function is called immediately before painting."""
        ##glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)  ## requires z-sorting to render properly.
        #glBlendFunc(GL_SRC_ALPHA, GL_ONE)
        #glEnable( GL_BLEND )
        #glEnable( GL_ALPHA_TEST )
        #glDisable( GL_DEPTH_TEST )
        
        ##glEnable( GL_POINT_SMOOTH )

        ##glHint(GL_POINT_SMOOTH_HINT, GL_NICEST)
        ##glPointParameterfv(GL_POINT_DISTANCE_ATTENUATION, (0, 0, -1e-3))
        ##glPointParameterfv(GL_POINT_SIZE_MAX, (65500,))
        ##glPointParameterfv(GL_POINT_SIZE_MIN, (0,))
        
    def paint(self):
        self.setupGLState()
        
        glEnable(GL_POINT_SPRITE)
        
        glActiveTexture(GL_TEXTURE0)
        glEnable( GL_TEXTURE_2D )
        glBindTexture(GL_TEXTURE_2D, self.pointTexture)
    
        glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE)
        #glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE)    ## use texture color exactly
        #glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE )  ## texture modulates current color
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE)
        glEnable(GL_PROGRAM_POINT_SIZE)
        
            
        with self.shader:
            #glUniform1i(self.shader.uniform('texture'), 0)  ## inform the shader which texture to use
            glEnableClientState(GL_VERTEX_ARRAY)
            try:
                pos = self.pos
                #if pos.ndim > 2:
                    #pos = pos.reshape((reduce(lambda a,b: a*b, pos.shape[:-1]), pos.shape[-1]))
                glVertexPointerf(pos)
            
                if isinstance(self.color, np.ndarray):
                    glEnableClientState(GL_COLOR_ARRAY)
                    glColorPointerf(self.color)
                else:
                    if isinstance(self.color, QtGui.QColor):
                        glColor4f(*fn.glColor(self.color))
                    else:
                        glColor4f(*self.color)
                
                if not self.pxMode or isinstance(self.size, np.ndarray):
                    glEnableClientState(GL_NORMAL_ARRAY)
                    norm = np.empty(pos.shape)
                    if self.pxMode:
                        norm[...,0] = self.size
                    else:
                        gpos = self.mapToView(pos.transpose()).transpose()
                        pxSize = self.view().pixelSize(gpos)
                        norm[...,0] = self.size / pxSize
                    
                    glNormalPointerf(norm)
                else:
                    glNormal3f(self.size, 0, 0)  ## vertex shader uses norm.x to determine point size
                    #glPointSize(self.size)
                glDrawArrays(GL_POINTS, 0, int(pos.size / pos.shape[-1]))
            finally:
                glDisableClientState(GL_NORMAL_ARRAY)
                glDisableClientState(GL_VERTEX_ARRAY)
                glDisableClientState(GL_COLOR_ARRAY)
                #posVBO.unbind()
                
        #for i in range(len(self.pos)):
            #pos = self.pos[i]
            
            #if isinstance(self.color, np.ndarray):
                #color = self.color[i]
            #else:
                #color = self.color
            #if isinstance(self.color, QtGui.QColor):
                #color = fn.glColor(self.color)
                
            #if isinstance(self.size, np.ndarray):
                #size = self.size[i]
            #else:
                #size = self.size
                
            #pxSize = self.view().pixelSize(QtGui.QVector3D(*pos))
            
            #glPointSize(size / pxSize)
            #glBegin( GL_POINTS )
            #glColor4f(*color)  # x is blue
            ##glNormal3f(size, 0, 0)
            #glVertex3f(*pos)
            #glEnd()

        
        
        
        
