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# Source code for pyqtgraph.opengl.items.GLLinePlotItem

    import enum
    import importlib

    from OpenGL import GL
    from OpenGL.GL import shaders
    import numpy as np

    from ...Qt import QtGui, QT_LIB
    from ... import functions as fn
    from ..GLGraphicsItem import GLGraphicsItem

    if QT_LIB in ["PyQt5", "PySide2"]:
        QtOpenGL = QtGui
    else:
        QtOpenGL = importlib.import_module(f"{QT_LIB}.QtOpenGL")

    __all__ = ['GLLinePlotItem']

    class DirtyFlag(enum.Flag):
        POSITION = enum.auto()
        COLOR = enum.auto()

    class GLLinePlotItem(GLGraphicsItem):
        """Draws line plots in 3D."""

        _shaderProgram = None

        def __init__(self, parentItem=None, **kwds):
            """All keyword arguments are passed to setData()"""
            super().__init__()
            glopts = kwds.pop('glOptions', 'additive')
            self.setGLOptions(glopts)
            self.pos = None
            self.mode = 'line_strip'
            self.width = 1.
            self.color = (1.0,1.0,1.0,1.0)
            self.antialias = False

            self.m_vbo_position = QtOpenGL.QOpenGLBuffer(QtOpenGL.QOpenGLBuffer.Type.VertexBuffer)
            self.m_vbo_color = QtOpenGL.QOpenGLBuffer(QtOpenGL.QOpenGLBuffer.Type.VertexBuffer)
            self.dirty_bits = DirtyFlag(0)

            self.setParentItem(parentItem)
            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 vertex 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) or
                                  tuple of floats specifying
                                  a single color for the entire item.
            width                 float specifying line width
            antialias             enables smooth line drawing
            mode                  'lines': Each pair of vertexes draws a single line
                                           segment.
                                  'line_strip': All vertexes are drawn as a
                                                continuous set of line segments.
            ====================  ==================================================
            """
            args = ['pos', 'color', 'width', 'mode', 'antialias']
            for k in kwds.keys():
                if k not in args:
                    raise Exception('Invalid keyword argument: %s (allowed arguments are %s)' % (k, str(args)))
            if 'pos' in kwds:
                pos = kwds.pop('pos')
                self.pos = np.ascontiguousarray(pos, dtype=np.float32)
                self.dirty_bits |= DirtyFlag.POSITION
            if 'color' in kwds:
                color = kwds.pop('color')
                if isinstance(color, np.ndarray):
                    color = np.ascontiguousarray(color, dtype=np.float32)
                    self.dirty_bits |= DirtyFlag.COLOR
                if isinstance(color, str):
                    color = fn.mkColor(color)
                if isinstance(color, QtGui.QColor):
                    color = color.getRgbF()
                self.color = color
            for k, v in kwds.items():
                setattr(self, k, v)

            if self.mode not in ['line_strip', 'lines']:
                raise ValueError("Unknown line mode '%s'. (must be 'lines' or 'line_strip')" % self.mode)

            self.update()

        def upload_vbo(self, vbo, arr):
            if arr is None:
                vbo.destroy()
                return
            if not vbo.isCreated():
                vbo.create()
            vbo.bind()
            if vbo.size() != arr.nbytes:
                vbo.allocate(arr, arr.nbytes)
            else:
                vbo.write(0, arr, arr.nbytes)
            vbo.release()

        @staticmethod
        def getShaderProgram():
            klass = GLLinePlotItem

            if klass._shaderProgram is not None:
                return klass._shaderProgram

            ctx = QtGui.QOpenGLContext.currentContext()
            fmt = ctx.format()

            if ctx.isOpenGLES():
                if fmt.version() >= (3, 0):
                    glsl_version = "#version 300 es\n"
                    sources = SHADER_CORE
                else:
                    glsl_version = ""
                    sources = SHADER_LEGACY
            else:
                if fmt.version() >= (3, 1):
                    glsl_version = "#version 140\n"
                    sources = SHADER_CORE
                else:
                    glsl_version = ""
                    sources = SHADER_LEGACY

            compiled = [shaders.compileShader([glsl_version, v], k) for k, v in sources.items()]
            program = shaders.compileProgram(*compiled)

            # bind generic vertex attrib 0 to "a_position" so that
            # vertex attrib 0 definitely gets enabled later.
            GL.glBindAttribLocation(program, 0, "a_position")
            GL.glBindAttribLocation(program, 1, "a_color")
            GL.glLinkProgram(program)

            klass._shaderProgram = program
            return program

        def paint(self):
            if self.pos is None:
                return
            self.setupGLState()

            mat_mvp = self.mvpMatrix()
            mat_mvp = np.array(mat_mvp.data(), dtype=np.float32)

            context = QtGui.QOpenGLContext.currentContext()

            if DirtyFlag.POSITION in self.dirty_bits:
                self.upload_vbo(self.m_vbo_position, self.pos)
            if DirtyFlag.COLOR in self.dirty_bits:
                self.upload_vbo(self.m_vbo_color, self.color)
            self.dirty_bits = DirtyFlag(0)

            program = self.getShaderProgram()

            enabled_locs = []

            loc = 0
            self.m_vbo_position.bind()
            GL.glVertexAttribPointer(loc, 3, GL.GL_FLOAT, False, 0, None)
            self.m_vbo_position.release()
            enabled_locs.append(loc)

            loc = 1
            if isinstance(self.color, np.ndarray):
                self.m_vbo_color.bind()
                GL.glVertexAttribPointer(loc, 4, GL.GL_FLOAT, False, 0, None)
                self.m_vbo_color.release()
                enabled_locs.append(loc)
            else:
                GL.glVertexAttrib4f(loc, *self.color)

            enable_aa = self.antialias and not context.isOpenGLES()

            if enable_aa:
                GL.glEnable(GL.GL_LINE_SMOOTH)
                GL.glEnable(GL.GL_BLEND)
                GL.glBlendFuncSeparate(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA,
                                       GL.GL_ONE, GL.GL_ONE_MINUS_SRC_ALPHA)
                GL.glHint(GL.GL_LINE_SMOOTH_HINT, GL.GL_NICEST)

            sfmt = context.format()
            core_forward_compatible = (
                sfmt.profile() == sfmt.OpenGLContextProfile.CoreProfile
                and not sfmt.testOption(sfmt.FormatOption.DeprecatedFunctions)
            )
            if not core_forward_compatible:
                # Core Forward Compatible profiles will return error for
                # any width that is not 1.0
                GL.glLineWidth(self.width)

            for loc in enabled_locs:
                GL.glEnableVertexAttribArray(loc)

            with program:
                loc = GL.glGetUniformLocation(program, "u_mvp")
                GL.glUniformMatrix4fv(loc, 1, False, mat_mvp)

                if self.mode == 'line_strip':
                    GL.glDrawArrays(GL.GL_LINE_STRIP, 0, len(self.pos))
                elif self.mode == 'lines':
                    GL.glDrawArrays(GL.GL_LINES, 0, len(self.pos))

            for loc in enabled_locs:
                GL.glDisableVertexAttribArray(loc)

            if enable_aa:
                GL.glDisable(GL.GL_LINE_SMOOTH)
                GL.glDisable(GL.GL_BLEND)

            GL.glLineWidth(1.0)

    SHADER_LEGACY = {
        GL.GL_VERTEX_SHADER : """
            uniform mat4 u_mvp;
            attribute vec4 a_position;
            attribute vec4 a_color;
            varying vec4 v_color;
            void main() {
                v_color = a_color;
                gl_Position = u_mvp * a_position;
            }
        """,
        GL.GL_FRAGMENT_SHADER : """
            #ifdef GL_ES
            precision mediump float;
            #endif
            varying vec4 v_color;
            void main() {
                gl_FragColor = v_color;
            }
        """,
    }

    SHADER_CORE = {
        GL.GL_VERTEX_SHADER : """
            uniform mat4 u_mvp;
            in vec4 a_position;
            in vec4 a_color;
            out vec4 v_color;
            void main() {
                v_color = a_color;
                gl_Position = u_mvp * a_position;
            }
        """,
        GL.GL_FRAGMENT_SHADER : """
            #ifdef GL_ES
            precision mediump float;
            #endif
            in vec4 v_color;
            out vec4 fragColor;
            void main() {
                fragColor = v_color;
            }
        """,
    }