# The Vision Egg: Gratings
#
# Copyright (C) 2001-2003 Andrew Straw.
# Copyright (C) 2005,2008 California Institute of Technology
#
# URL: <http://www.visionegg.org/>
#
# Distributed under the terms of the GNU Lesser General Public License
# (LGPL). See LICENSE.TXT that came with this file.

"""
Grating stimuli.

"""

####################################################################
#
#        Import all the necessary packages
#
####################################################################

import logging                              # available in Python 2.3

import VisionEgg
import VisionEgg.Core
import VisionEgg.Textures
import VisionEgg.ParameterTypes as ve_types
import numpy
import math, types, string
import VisionEgg.GL as gl # get all OpenGL stuff in one namespace
import _vegl

def _get_type_info( bitdepth ):
    """Private helper function to calculate type info based on bit depth"""
    if bitdepth == 8:
        gl_type = gl.GL_UNSIGNED_BYTE
        numpy_dtype = numpy.uint8
        max_int_val = float((2**8)-1)
    elif bitdepth == 12:
        gl_type = gl.GL_SHORT
        numpy_dtype = numpy.int16
        max_int_val = float((2**15)-1)
    elif bitdepth == 16:
        gl_type = gl.GL_INT
        numpy_dtype = numpy.int32
        max_int_val = float((2.**31.)-1) # do as float to avoid overflow
    else:
        raise ValueError("supported bitdepths are 8, 12, and 16.")
    return gl_type, numpy_dtype, max_int_val

class LuminanceGratingCommon(VisionEgg.Core.Stimulus):
    """Base class with common code to all ways of drawing luminance gratings.

    Parameters
    ==========
    bit_depth -- precision with which grating is calculated and sent to OpenGL (UnsignedInteger)
                 Default: 8
    """

    parameters_and_defaults = VisionEgg.ParameterDefinition({
        'bit_depth':(8,
                     ve_types.UnsignedInteger,
                     'precision with which grating is calculated and sent to OpenGL'),
        })

    __slots__ = (
        'gl_internal_format',
        'format',
        'gl_type',
        'numpy_dtype',
        'max_int_val',
        'cached_bit_depth',
        )

    def calculate_bit_depth_dependencies(self):
        """Calculate a number of parameters dependent on bit depth."""
        bit_depth_warning = False
        p = self.parameters # shorthand

        red_bits = gl.glGetIntegerv( gl.GL_RED_BITS )
        green_bits = gl.glGetIntegerv( gl.GL_GREEN_BITS )
        blue_bits = gl.glGetIntegerv( gl.GL_BLUE_BITS )
        min_bits = min( (red_bits,green_bits,blue_bits) )
        if min_bits < p.bit_depth:
            logger = logging.getLogger('VisionEgg.Gratings')
            logger.warning("Requested bit depth of %d in "
                           "LuminanceGratingCommon, which is "
                           "greater than your current OpenGL context "
                           "supports (%d)."% (p.bit_depth,min_bits))
        self.gl_internal_format = gl.GL_LUMINANCE
        self.format = gl.GL_LUMINANCE
        self.gl_type, self.numpy_dtype, self.max_int_val = _get_type_info( p.bit_depth )
        self.cached_bit_depth = p.bit_depth

class AlphaGratingCommon(VisionEgg.Core.Stimulus):
    """Base class with common code to all ways of drawing gratings in alpha.

    This class is currently not used by any other classes.

    Parameters
    ==========
    bit_depth -- precision with which grating is calculated and sent to OpenGL (UnsignedInteger)
                 Default: 8
    """

    parameters_and_defaults = VisionEgg.ParameterDefinition({
        'bit_depth':(8,
                     ve_types.UnsignedInteger,
                     'precision with which grating is calculated and sent to OpenGL'),
        })

    __slots__ = (
        'gl_internal_format',
        'format',
        'gl_type',
        'numpy_dtype',
        'max_int_val',
        'cached_bit_depth',
        )

    def calculate_bit_depth_dependencies(self):
        """Calculate a number of parameters dependent on bit depth."""
        p = self.parameters # shorthand
        alpha_bit_depth = gl.glGetIntegerv( gl.GL_ALPHA_BITS )
        if alpha_bit_depth < p.bit_depth:
            logger = logging.getLogger('VisionEgg.Gratings')
            logger.warning("Requested bit depth of %d, which is "
                           "greater than your current OpenGL context "
                           "supports (%d)."% (p.bit_depth,min_bits))
        self.gl_internal_format = gl.GL_ALPHA
        self.format = gl.GL_ALPHA
        self.gl_type, self.numpy_dtype, self.max_int_val = _get_type_info( p.bit_depth )
        self.cached_bit_depth = p.bit_depth

class SinGrating2D(LuminanceGratingCommon):
    """Sine wave grating stimulus

    This is a general-purpose, realtime sine-wave luminace grating
    generator. To acheive an arbitrary orientation, this class rotates
    a textured quad.  To draw a grating with sides that always remain
    horizontal and vertical, draw a large grating in a small viewport.
    (The viewport will clip anything beyond its edges.)

    Parameters
    ==========
    anchor                      -- specifies how position parameter is interpreted (String)
                                   Default: center
    bit_depth                   -- precision with which grating is calculated and sent to OpenGL (UnsignedInteger)
                                   Inherited from LuminanceGratingCommon
                                   Default: 8
    color1                      -- (AnyOf(Sequence3 of Real or Sequence4 of Real))
                                   Default: (1.0, 1.0, 1.0)
    color2                      -- optional color with which to perform interpolation with color1 in RGB space (AnyOf(Sequence3 of Real or Sequence4 of Real))
                                   Default: (determined at runtime)
    contrast                    -- (Real)
                                   Default: 1.0
    depth                       -- (Real)
                                   Default: (determined at runtime)
    ignore_time                 -- (Boolean)
                                   Default: False
    mask                        -- optional masking function (Instance of <class 'VisionEgg.Textures.Mask2D'>)
                                   Default: (determined at runtime)
    max_alpha                   -- (Real)
                                   Default: 1.0
    num_samples                 -- (UnsignedInteger)
                                   Default: 512
    on                          -- draw stimulus? (Boolean)
                                   Default: True
    orientation                 -- (Real)
                                   Default: 0.0
    pedestal                    -- (Real)
                                   Default: 0.5
    phase_at_t0                 -- (Real)
                                   Default: 0.0
    position                    -- (units: eye coordinates) (Sequence2 of Real)
                                   Default: (320.0, 240.0)
    recalculate_phase_tolerance -- (Real)
                                   Default: (determined at runtime)
    size                        -- defines coordinate size of grating (in eye coordinates) (Sequence2 of Real)
                                   Default: (640.0, 480.0)
    spatial_freq                -- frequency defined relative to coordinates defined in size parameter (units: cycles/eye_coord_unit) (Real)
                                   Default: 0.0078125
    t0_time_sec_absolute        -- (Real)
                                   Default: (determined at runtime)
    temporal_freq_hz            -- (Real)
                                   Default: 5.0
    """

    parameters_and_defaults = VisionEgg.ParameterDefinition({
        'on':(True,
              ve_types.Boolean,
              "draw stimulus?"),
        'mask':(None, # allows window onto otherwise (tilted) rectangular grating
                ve_types.Instance(VisionEgg.Textures.Mask2D),
                "optional masking function"),
        'contrast':(1.0,
                    ve_types.Real),
        'pedestal':(0.5,
                    ve_types.Real),
        'position':((320.0,240.0), # in eye coordinates
                    ve_types.Sequence2(ve_types.Real),
                    "(units: eye coordinates)"),
        'anchor':('center',
                  ve_types.String,
                  "specifies how position parameter is interpreted"),
        'depth':(None, # if not None, turns on depth testing and allows for occlusion
                 ve_types.Real),
        'size':((640.0,480.0),
                ve_types.Sequence2(ve_types.Real),
                "defines coordinate size of grating (in eye coordinates)",
                ),
        'spatial_freq':(1.0/128.0, # cycles/eye coord units
                        ve_types.Real,
                        "frequency defined relative to coordinates defined in size parameter (units: cycles/eye_coord_unit)",
                        ),
        'temporal_freq_hz':(5.0, # hz
                            ve_types.Real),
        't0_time_sec_absolute':(None, # Will be assigned during first call to draw()
                                ve_types.Real),
        'ignore_time':(False, # ignore temporal frequency variable - allow control purely with phase_at_t0
                       ve_types.Boolean),
        'phase_at_t0':(0.0, # degrees [0.0-360.0]
                       ve_types.Real),
        'orientation':(0.0, # 0=right, 90=up
                       ve_types.Real),
        'num_samples':(512, # number of spatial samples, should be a power of 2
                       ve_types.UnsignedInteger),
        'max_alpha':(1.0, # controls "opacity": 1.0 = completely opaque, 0.0 = completely transparent
                     ve_types.Real),
        'color1':((1.0, 1.0, 1.0), # alpha is ignored (if given) -- use max_alpha parameter
                  ve_types.AnyOf(ve_types.Sequence3(ve_types.Real),
                                 ve_types.Sequence4(ve_types.Real))),
        'color2':(None, # perform interpolation with color1 in RGB space.
                  ve_types.AnyOf(ve_types.Sequence3(ve_types.Real),
                                 ve_types.Sequence4(ve_types.Real)),
                  "optional color with which to perform interpolation with color1 in RGB space"),
        'recalculate_phase_tolerance':(None, # only recalculate texture when phase is changed by more than this amount, None for always recalculate. (Saves time.)
                                       ve_types.Real),
        })

    __slots__ = (
        '_texture_object_id',
        '_last_phase',
        )

    def __init__(self,**kw):
        LuminanceGratingCommon.__init__(self,**kw)

        p = self.parameters # shorthand

        self._texture_object_id = gl.glGenTextures(1)
        if p.mask:
            gl.glActiveTextureARB(gl.GL_TEXTURE0_ARB)
        gl.glBindTexture(gl.GL_TEXTURE_1D,self._texture_object_id)

        # Do error-checking on texture to make sure it will load
        max_dim = gl.glGetIntegerv(gl.GL_MAX_TEXTURE_SIZE)
        if p.num_samples > max_dim:
            raise NumSamplesTooLargeError("Grating num_samples too large for video system.\nOpenGL reports maximum size of %d"%(max_dim,))

        self.calculate_bit_depth_dependencies()

        w = p.size[0]
        inc = w/float(p.num_samples)
        phase = 0.0 # this data won't get used - don't care about phase
        self._last_phase = phase
        floating_point_sin = numpy.sin(2.0*math.pi*p.spatial_freq*numpy.arange(0.0,w,inc,dtype=numpy.float)+(phase/180.0*math.pi))*0.5*p.contrast+p.pedestal
        floating_point_sin = numpy.clip(floating_point_sin,0.0,1.0) # allow square wave generation if contrast > 1
        texel_data = (floating_point_sin*self.max_int_val).astype(self.numpy_dtype).tostring()

        # Because the MAX_TEXTURE_SIZE method is insensitive to the current
        # state of the video system, another check must be done using
        # "proxy textures".
        gl.glTexImage1D(gl.GL_PROXY_TEXTURE_1D,            # target
                        0,                                 # level
                        self.gl_internal_format,           # video RAM internal format
                        p.num_samples,                     # width
                        0,                                 # border
                        self.format,                       # format of texel data
                        self.gl_type,                      # type of texel data
                        texel_data)                        # texel data (irrelevant for proxy)
        if gl.glGetTexLevelParameteriv(gl.GL_PROXY_TEXTURE_1D, # Need PyOpenGL >= 2.0
                                       0,
                                       gl.GL_TEXTURE_WIDTH) == 0:
            raise NumSamplesTooLargeError("Grating num_samples is too wide for your video system!")

        # If we got here, it worked and we can load the texture for real.
        gl.glTexImage1D(gl.GL_TEXTURE_1D,                  # target
                        0,                                 # level
                        self.gl_internal_format,           # video RAM internal format
                        p.num_samples,                     # width
                        0,                                 # border
                        self.format,                       # format of texel data
                        self.gl_type,                      # type of texel data
                        texel_data)                        # texel data

        # Set texture object defaults
        gl.glTexParameteri(gl.GL_TEXTURE_1D,gl.GL_TEXTURE_WRAP_S,gl.GL_CLAMP_TO_EDGE)
        gl.glTexParameteri(gl.GL_TEXTURE_1D,gl.GL_TEXTURE_WRAP_T,gl.GL_CLAMP_TO_EDGE)
        gl.glTexParameteri(gl.GL_TEXTURE_1D,gl.GL_TEXTURE_MAG_FILTER,gl.GL_LINEAR)
        gl.glTexParameteri(gl.GL_TEXTURE_1D,gl.GL_TEXTURE_MIN_FILTER,gl.GL_LINEAR)

        if p.color2 is not None:
            if VisionEgg.Core.gl_renderer == 'ATi Rage 128 Pro OpenGL Engine' and VisionEgg.Core.gl_version == '1.1 ATI-1.2.22':
                logger = logging.getLogger('VisionEgg.Gratings')
                logger.warning("Your video card and driver have known "
                               "bugs which prevent them from rendering "
                               "color gratings properly.")

    def __del__(self):
        gl.glDeleteTextures( [self._texture_object_id] )

    def draw(self):
        p = self.parameters # shorthand
        if p.on:
            # calculate center
            center = VisionEgg._get_center(p.position,p.anchor,p.size)
            if p.mask:
                gl.glActiveTextureARB(gl.GL_TEXTURE0_ARB)
            gl.glBindTexture(gl.GL_TEXTURE_1D,self._texture_object_id)

            gl.glEnable(gl.GL_TEXTURE_1D)
            gl.glDisable(gl.GL_TEXTURE_2D)
            if p.bit_depth != self.cached_bit_depth:
                self.calculate_bit_depth_dependencies()

            # Clear the modeview matrix
            gl.glMatrixMode(gl.GL_MODELVIEW)
            gl.glPushMatrix()

            # Rotate about the center of the texture
            gl.glTranslate(center[0],
                           center[1],
                           0)
            gl.glRotate(p.orientation,0,0,1)

            if p.depth is None:
                gl.glDisable(gl.GL_DEPTH_TEST)
                depth = 0.0
            else:
                gl.glEnable(gl.GL_DEPTH_TEST)
                depth = p.depth

            # allow max_alpha value to control blending
            gl.glEnable( gl.GL_BLEND )
            gl.glBlendFunc( gl.GL_SRC_ALPHA, gl.GL_ONE_MINUS_SRC_ALPHA )

            if p.color2:
                gl.glTexEnvi(gl.GL_TEXTURE_ENV, gl.GL_TEXTURE_ENV_MODE, gl.GL_BLEND)
                gl.glTexEnvfv(gl.GL_TEXTURE_ENV, gl.GL_TEXTURE_ENV_COLOR, p.color2)
                ## alpha is ignored because the texture base internal format is luminance
            else:
                gl.glTexEnvi(gl.GL_TEXTURE_ENV, gl.GL_TEXTURE_ENV_MODE, gl.GL_MODULATE)

            if p.t0_time_sec_absolute is None and not p.ignore_time:
                p.t0_time_sec_absolute = VisionEgg.time_func()

            w = p.size[0]
            inc = w/float(p.num_samples)
            if p.ignore_time:
                phase = p.phase_at_t0
            else:
                t_var = VisionEgg.time_func() - p.t0_time_sec_absolute
                phase = t_var*p.temporal_freq_hz*-360.0 + p.phase_at_t0
            if p.recalculate_phase_tolerance is None or abs(self._last_phase - phase) > p.recalculate_phase_tolerance:
                self._last_phase = phase # we're re-drawing the phase at this angle
                floating_point_sin = numpy.sin(2.0*math.pi*p.spatial_freq*numpy.arange(0.0,w,inc,dtype=numpy.float)+(phase/180.0*math.pi))*0.5*p.contrast+p.pedestal
                floating_point_sin = numpy.clip(floating_point_sin,0.0,1.0) # allow square wave generation if contrast > 1
                texel_data = (floating_point_sin*self.max_int_val).astype(self.numpy_dtype)
                # PyOpenGL 2.0.1.09 has a bug, so use our own wrapper
                _vegl.veglTexSubImage1D(gl.GL_TEXTURE_1D, # target
                                        0,                # level
                                        0,                # x offset
                                        p.num_samples,    # width
                                        self.format,      # format of new texel data
                                        self.gl_type,     # type of new texel data
                                        texel_data)       # new texel data
                if 0:
                    compare_array = numpy.empty(texel_data.shape,dtype=texel_data.dtype)
                    pixels = _vegl.veglGetTexImage(gl.GL_TEXTURE_1D, # target
                                                   0, # level
                                                   self.format, # format
                                                   self.gl_type, # type
                                                   compare_array)
                    assert numpy.allclose( compare_array, texel_data )

            h_w = p.size[0]/2.0
            h_h = p.size[1]/2.0

            l = -h_w
            r = h_w
            b = -h_h
            t = h_h

            # in the case of only color1,
            # the texel data multiplies color1 to produce a color

            # with color2,
            # the texel data linearly interpolates between color1 and color2

            gl.glColor4f(p.color1[0],p.color1[1],p.color1[2],p.max_alpha)

            if p.mask:
                p.mask.draw_masked_quad(0.0,1.0,0.0,1.0, # l,r,b,t for texture coordinates
                                        l,r,b,t, # l,r,b,t in eye coordinates
                                        depth ) # also in eye coordinates
            else:
                # draw unmasked quad
                gl.glBegin(gl.GL_QUADS)

                gl.glTexCoord2f(0.0,0.0)
                gl.glVertex3f(l,b,depth)

                gl.glTexCoord2f(1.0,0.0)
                gl.glVertex3f(r,b,depth)

                gl.glTexCoord2f(1.0,1.0)
                gl.glVertex3f(r,t,depth)

                gl.glTexCoord2f(0.0,1.0)
                gl.glVertex3f(l,t,depth)
                gl.glEnd() # GL_QUADS

            gl.glDisable(gl.GL_TEXTURE_1D)
            gl.glPopMatrix()

class SinGrating3D(LuminanceGratingCommon):
    """Sine wave grating stimulus texture mapped onto quad in 3D

    This is a general-purpose, realtime sine-wave luminace grating
    generator. This 3D version doesn't support an orientation
    parameter.  This could be implemented, but for now should be done
    by orienting the quad in 3D.

    Parameters
    ==========
    bit_depth                   -- precision with which grating is calculated and sent to OpenGL (UnsignedInteger)
                                   Inherited from LuminanceGratingCommon
                                   Default: 8
    color1                      -- (AnyOf(Sequence3 of Real or Sequence4 of Real))
                                   Default: (1.0, 1.0, 1.0)
    color2                      -- optional color with which to perform interpolation with color1 in RGB space (AnyOf(Sequence3 of Real or Sequence4 of Real))
                                   Default: (determined at runtime)
    contrast                    -- (Real)
                                   Default: 1.0
    depth                       -- (Real)
                                   Default: (determined at runtime)
    depth_test                  -- perform depth test? (Boolean)
                                   Default: True
    ignore_time                 -- (Boolean)
                                   Default: False
    lowerleft                   -- vertex position (units: eye coordinates) (AnyOf(Sequence3 of Real or Sequence4 of Real))
                                   Default: (0.0, 0.0, -1.0)
    lowerright                  -- vertex position (units: eye coordinates) (AnyOf(Sequence3 of Real or Sequence4 of Real))
                                   Default: (1.0, 0.0, -1.0)
    mask                        -- optional masking function (Instance of <class 'VisionEgg.Textures.Mask2D'>)
                                   Default: (determined at runtime)
    max_alpha                   -- (Real)
                                   Default: 1.0
    num_samples                 -- (UnsignedInteger)
                                   Default: 512
    on                          -- draw stimulus? (Boolean)
                                   Default: True
    pedestal                    -- (Real)
                                   Default: 0.5
    phase_at_t0                 -- (Real)
                                   Default: 0.0
    recalculate_phase_tolerance -- (Real)
                                   Default: (determined at runtime)
    size                        -- defines coordinate size of grating (in eye coordinates) (Sequence2 of Real)
                                   Default: (1.0, 1.0)
    spatial_freq                -- frequency defined relative to coordinates defined in size parameter (units; cycles/eye_coord_unit) (Real)
                                   Default: 4.0
    t0_time_sec_absolute        -- (Real)
                                   Default: (determined at runtime)
    temporal_freq_hz            -- (Real)
                                   Default: 5.0
    upperleft                   -- vertex position (units: eye coordinates) (AnyOf(Sequence3 of Real or Sequence4 of Real))
                                   Default: (0.0, 1.0, -1.0)
    upperright                  -- vertex position (units: eye coordinates) (AnyOf(Sequence3 of Real or Sequence4 of Real))
                                   Default: (1.0, 1.0, -1.0)
    """

    parameters_and_defaults = VisionEgg.ParameterDefinition({
        'on':(True,
              ve_types.Boolean,
              "draw stimulus?"),
        'mask':(None, # allows window onto otherwise (tilted) rectangular grating
                ve_types.Instance(VisionEgg.Textures.Mask2D),
                "optional masking function"),
        'contrast':(1.0,
                    ve_types.Real),
        'pedestal':(0.5,
                    ve_types.Real),
        'depth':(None, # if not None, turns on depth testing and allows for occlusion
                 ve_types.Real),
        'size':((1.0,1.0), # in eye coordinates
                ve_types.Sequence2(ve_types.Real),
                "defines coordinate size of grating (in eye coordinates)"),
        'spatial_freq':(4.0, # cycles/eye coord units
                        ve_types.Real,
                        "frequency defined relative to coordinates defined in size parameter (units; cycles/eye_coord_unit)"),
        'temporal_freq_hz':(5.0, # hz
                            ve_types.Real),
        't0_time_sec_absolute':(None, # Will be assigned during first call to draw()
                                ve_types.Real),
        'ignore_time':(False, # ignore temporal frequency variable - allow control purely with phase_at_t0
                       ve_types.Boolean),
        'phase_at_t0':(0.0, # degrees [0.0-360.0]
                       ve_types.Real),
        'num_samples':(512, # number of spatial samples, should be a power of 2
                       ve_types.UnsignedInteger),
        'max_alpha':(1.0, # controls "opacity": 1.0 = completely opaque, 0.0 = completely transparent
                     ve_types.Real),
        'color1':((1.0, 1.0, 1.0), # alpha is ignored (if given) -- use max_alpha parameter
                  ve_types.AnyOf(ve_types.Sequence3(ve_types.Real),
                                 ve_types.Sequence4(ve_types.Real))),
        'color2':(None, # perform interpolation with color1 in RGB space.
                  ve_types.AnyOf(ve_types.Sequence3(ve_types.Real),
                                 ve_types.Sequence4(ve_types.Real)),
                  "optional color with which to perform interpolation with color1 in RGB space"),
        'recalculate_phase_tolerance':(None, # only recalculate texture when phase is changed by more than this amount, None for always recalculate. (Saves time.)
                                       ve_types.Real),
        'depth_test':(True,
                      ve_types.Boolean,
                      "perform depth test?"),
        'lowerleft':((0.0,0.0,-1.0), # in eye coordinates
                     ve_types.AnyOf(ve_types.Sequence3(ve_types.Real),
                                    ve_types.Sequence4(ve_types.Real)),
                     "vertex position (units: eye coordinates)"),
        'lowerright':((1.0,0.0,-1.0), # in eye coordinates
                      ve_types.AnyOf(ve_types.Sequence3(ve_types.Real),
                                     ve_types.Sequence4(ve_types.Real)),
                      "vertex position (units: eye coordinates)"),
        'upperleft':((0.0,1.0,-1.0), # in eye coordinates
                     ve_types.AnyOf(ve_types.Sequence3(ve_types.Real),
                                    ve_types.Sequence4(ve_types.Real)),
                     "vertex position (units: eye coordinates)"),
        'upperright':((1.0,1.0,-1.0), # in eye coordinates
                      ve_types.AnyOf(ve_types.Sequence3(ve_types.Real),
                                     ve_types.Sequence4(ve_types.Real)),
                      "vertex position (units: eye coordinates)"),
        })

    __slots__ = (
        '_texture_object_id',
        '_last_phase',
        )

    def __init__(self,**kw):
        LuminanceGratingCommon.__init__(self,**kw)

        p = self.parameters # shorthand

        self._texture_object_id = gl.glGenTextures(1)
        if p.mask:
            gl.glActiveTextureARB(gl.GL_TEXTURE0_ARB)
        gl.glBindTexture(gl.GL_TEXTURE_1D,self._texture_object_id)

        # Do error-checking on texture to make sure it will load
        max_dim = gl.glGetIntegerv(gl.GL_MAX_TEXTURE_SIZE)
        if p.num_samples > max_dim:
            raise NumSamplesTooLargeError("Grating num_samples too large for video system.\nOpenGL reports maximum size of %d"%(max_dim,))

        self.calculate_bit_depth_dependencies()

        w = p.size[0]
        inc = w/float(p.num_samples)
        phase = 0.0 # this data won't get used - don't care about phase
        self._last_phase = phase
        floating_point_sin = numpy.sin(2.0*math.pi*p.spatial_freq*numpy.arange(0.0,w,inc,dtype=numpy.float)+(phase/180.0*math.pi))*0.5*p.contrast+p.pedestal
        floating_point_sin = numpy.clip(floating_point_sin,0.0,1.0) # allow square wave generation if contrast > 1
        texel_data = (floating_point_sin*self.max_int_val).astype(self.numpy_dtype).tostring()

        # Because the MAX_TEXTURE_SIZE method is insensitive to the current
        # state of the video system, another check must be done using
        # "proxy textures".
        gl.glTexImage1D(gl.GL_PROXY_TEXTURE_1D,            # target
                        0,                                 # level
                        self.gl_internal_format,           # video RAM internal format
                        p.num_samples,                     # width
                        0,                                 # border
                        self.format,                       # format of texel data
                        self.gl_type,                      # type of texel data
                        texel_data)                        # texel data (irrelevant for proxy)
        if gl.glGetTexLevelParameteriv(gl.GL_PROXY_TEXTURE_1D, # Need PyOpenGL >= 2.0
                                       0,
                                       gl.GL_TEXTURE_WIDTH) == 0:
            raise NumSamplesTooLargeError("Grating num_samples is too wide for your video system!")

        # If we got here, it worked and we can load the texture for real.
        gl.glTexImage1D(gl.GL_TEXTURE_1D,                  # target
                        0,                                 # level
                        self.gl_internal_format,           # video RAM internal format
                        p.num_samples,                     # width
                        0,                                 # border
                        self.format,                       # format of texel data
                        self.gl_type,                      # type of texel data
                        texel_data)                        # texel data

        # Set texture object defaults
        gl.glTexParameteri(gl.GL_TEXTURE_1D,gl.GL_TEXTURE_WRAP_S,gl.GL_CLAMP_TO_EDGE)
        gl.glTexParameteri(gl.GL_TEXTURE_1D,gl.GL_TEXTURE_WRAP_T,gl.GL_CLAMP_TO_EDGE)
        gl.glTexParameteri(gl.GL_TEXTURE_1D,gl.GL_TEXTURE_MAG_FILTER,gl.GL_LINEAR)
        gl.glTexParameteri(gl.GL_TEXTURE_1D,gl.GL_TEXTURE_MIN_FILTER,gl.GL_LINEAR)

        if p.color2 is not None:
            if VisionEgg.Core.gl_renderer == 'ATi Rage 128 Pro OpenGL Engine' and VisionEgg.Core.gl_version == '1.1 ATI-1.2.22':
                logger = logging.getLogger('VisionEgg.Gratings')
                logger.warning("Your video card and driver have known "
                               "bugs which prevent them from rendering "
                               "color gratings properly.")

    def __del__(self):
        gl.glDeleteTextures( [self._texture_object_id] )

    def draw(self):
        p = self.parameters # shorthand
        if p.on:
            if p.mask:
                gl.glActiveTextureARB(gl.GL_TEXTURE0_ARB)
            if p.depth_test:
                gl.glEnable(gl.GL_DEPTH_TEST)
            else:
                gl.glDisable(gl.GL_DEPTH_TEST)
            gl.glBindTexture(gl.GL_TEXTURE_1D,self._texture_object_id)
            gl.glEnable(gl.GL_TEXTURE_1D)
            gl.glDisable(gl.GL_TEXTURE_2D)
            if p.bit_depth != self.cached_bit_depth:
                self.calculate_bit_depth_dependencies()

            # allow max_alpha value to control blending
            gl.glEnable( gl.GL_BLEND )
            gl.glBlendFunc( gl.GL_SRC_ALPHA, gl.GL_ONE_MINUS_SRC_ALPHA )

            if p.color2:
                gl.glTexEnvi(gl.GL_TEXTURE_ENV, gl.GL_TEXTURE_ENV_MODE, gl.GL_BLEND)
                gl.glTexEnvfv(gl.GL_TEXTURE_ENV, gl.GL_TEXTURE_ENV_COLOR, p.color2)
                ## alpha is ignored because the texture base internal format is luminance
            else:
                gl.glTexEnvi(gl.GL_TEXTURE_ENV, gl.GL_TEXTURE_ENV_MODE, gl.GL_MODULATE)

            if p.t0_time_sec_absolute is None and not p.ignore_time:
                p.t0_time_sec_absolute = VisionEgg.time_func()

            w = p.size[0]
            inc = w/float(p.num_samples)
            if p.ignore_time:
                phase = p.phase_at_t0
            else:
                t_var = VisionEgg.time_func() - p.t0_time_sec_absolute
                phase = t_var*p.temporal_freq_hz*-360.0 + p.phase_at_t0
            if p.recalculate_phase_tolerance is None or abs(self._last_phase - phase) > p.recalculate_phase_tolerance:
                self._last_phase = phase # we're re-drawing the phase at this angle
                floating_point_sin = numpy.sin(2.0*math.pi*p.spatial_freq*numpy.arange(0.0,w,inc,dtype=numpy.float)+(phase/180.0*math.pi))*0.5*p.contrast+p.pedestal
                floating_point_sin = numpy.clip(floating_point_sin,0.0,1.0) # allow square wave generation if contrast > 1
                texel_data = (floating_point_sin*self.max_int_val).astype(self.numpy_dtype).tostring()

                gl.glTexSubImage1D(gl.GL_TEXTURE_1D, # target
                                   0,                # level
                                   0,                # x offset
                                   p.num_samples,    # width
                                   self.format,      # format of new texel data
                                   self.gl_type,     # type of new texel data
                                   texel_data)       # new texel data

            # in the case of only color1,
            # the texel data multiplies color1 to produce a color

            # with color2,
            # the texel data linearly interpolates between color1 and color2

            gl.glColor4f(p.color1[0],p.color1[1],p.color1[2],p.max_alpha)

            if p.mask:
                p.mask.draw_masked_quad_3d(0.0,1.0,0.0,1.0, # for texture coordinates
                                           p.lowerleft,p.lowerright,p.upperright,p.upperleft)
            else:
                # draw unmasked quad
                gl.glBegin(gl.GL_QUADS)

                gl.glTexCoord2f(0.0,0.0)
                gl.glVertex(*p.lowerleft)

                gl.glTexCoord2f(1.0,0.0)
                gl.glVertex(*p.lowerright)

                gl.glTexCoord2f(1.0,1.0)
                gl.glVertex(*p.upperright)

                gl.glTexCoord2f(0.0,1.0)
                gl.glVertex(*p.upperleft)
                gl.glEnd() # GL_QUADS

            gl.glDisable(gl.GL_TEXTURE_1D)

class NumSamplesTooLargeError( RuntimeError ):
    pass
