# Source code for pyqtgraph.opengl.items.GLMeshItem

    from OpenGL.GL import *  # noqa
    import numpy as np

    from ...Qt import QtGui
    from .. import shaders
    from ..GLGraphicsItem import GLGraphicsItem
    from ..MeshData import MeshData

    __all__ = ['GLMeshItem']

    class GLMeshItem(GLGraphicsItem):
        """
        **Bases:** :class:`GLGraphicsItem <pyqtgraph.opengl.GLGraphicsItem.GLGraphicsItem>`

        Displays a 3D triangle mesh.
        """

        def __init__(self, parentItem=None, **kwds):
            """
            ============== =====================================================
            **Arguments:**
            meshdata       MeshData object from which to determine geometry for
                           this item.
            color          Default face color used if no vertex or face colors
                           are specified.
            edgeColor      Default edge color to use if no edge colors are
                           specified in the mesh data.
            drawEdges      If True, a wireframe mesh will be drawn.
                           (default=False)
            drawFaces      If True, mesh faces are drawn. (default=True)
            shader         Name of shader program to use when drawing faces.
                           (None for no shader)
            smooth         If True, normal vectors are computed for each vertex
                           and interpolated within each face.
            computeNormals If False, then computation of normal vectors is
                           disabled. This can provide a performance boost for
                           meshes that do not make use of normals.
            ============== =====================================================
            """
            self.opts = {
                'meshdata': None,
                'color': (1., 1., 1., 1.),
                'drawEdges': False,
                'drawFaces': True,
                'edgeColor': (0.5, 0.5, 0.5, 1.0),
                'shader': None,
                'smooth': True,
                'computeNormals': True,
            }

            super().__init__(parentItem=parentItem)
            glopts = kwds.pop('glOptions', 'opaque')
            self.setGLOptions(glopts)
            shader = kwds.pop('shader', None)
            self.setShader(shader)

            self.setMeshData(**kwds)

            ## storage for data compiled from MeshData object
            self.vertexes = None
            self.normals = None
            self.colors = None
            self.faces = None

        def setShader(self, shader):
            """Set the shader used when rendering faces in the mesh. (see the GL shaders example)"""
            self.opts['shader'] = shader
            self.update()

        def shader(self):
            shader = self.opts['shader']
            if isinstance(shader, shaders.ShaderProgram):
                return shader
            else:
                return shaders.getShaderProgram(shader)

        def setColor(self, c):
            """Set the default color to use when no vertex or face colors are specified."""
            self.opts['color'] = c
            self.update()

        def setMeshData(self, **kwds):
            """
            Set mesh data for this item. This can be invoked two ways:

            1. Specify *meshdata* argument with a new MeshData object
            2. Specify keyword arguments to be passed to MeshData(..) to create a new instance.
            """
            md = kwds.get('meshdata', None)
            if md is None:
                opts = {}
                for k in ['vertexes', 'faces', 'edges', 'vertexColors', 'faceColors']:
                    try:
                        opts[k] = kwds.pop(k)
                    except KeyError:
                        pass
                md = MeshData(**opts)

            self.opts['meshdata'] = md
            self.opts.update(kwds)
            self.meshDataChanged()
            self.update()

        def meshDataChanged(self):
            """
            This method must be called to inform the item that the MeshData object
            has been altered.
            """

            self.vertexes = None
            self.faces = None
            self.normals = None
            self.colors = None
            self.edges = None
            self.edgeColors = None
            self.update()

        def parseMeshData(self):
            ## interpret vertex / normal data before drawing
            ## This can:
            ##   - automatically generate normals if they were not specified
            ##   - pull vertexes/noormals/faces from MeshData if that was specified

            if self.vertexes is not None and self.normals is not None:
                return
            #if self.opts['normals'] is None:
                #if self.opts['meshdata'] is None:
                    #self.opts['meshdata'] = MeshData(vertexes=self.opts['vertexes'], faces=self.opts['faces'])
            if self.opts['meshdata'] is not None:
                md = self.opts['meshdata']
                if self.opts['smooth'] and not md.hasFaceIndexedData():
                    self.vertexes = md.vertexes()
                    if self.opts['computeNormals']:
                        self.normals = md.vertexNormals()
                    self.faces = md.faces()
                    if md.hasVertexColor():
                        self.colors = md.vertexColors()
                    if md.hasFaceColor():
                        self.colors = md.faceColors()
                else:
                    self.vertexes = md.vertexes(indexed='faces')
                    if self.opts['computeNormals']:
                        if self.opts['smooth']:
                            self.normals = md.vertexNormals(indexed='faces')
                        else:
                            self.normals = md.faceNormals(indexed='faces')
                    self.faces = None
                    if md.hasVertexColor():
                        self.colors = md.vertexColors(indexed='faces')
                    elif md.hasFaceColor():
                        self.colors = md.faceColors(indexed='faces')

                if self.opts['drawEdges']:
                    if not md.hasFaceIndexedData():
                        self.edges = md.edges()
                        self.edgeVerts = md.vertexes()
                    else:
                        self.edges = md.edges()
                        self.edgeVerts = md.vertexes(indexed='faces')
                return

        def paint(self):
            self.setupGLState()

            self.parseMeshData()

            if self.opts['drawFaces']:
                with self.shader():
                    verts = self.vertexes
                    norms = self.normals
                    color = self.colors
                    faces = self.faces
                    if verts is None:
                        return
                    glEnableClientState(GL_VERTEX_ARRAY)
                    try:
                        glVertexPointerf(verts)

                        if self.colors is None:
                            color = self.opts['color']
                            if isinstance(color, QtGui.QColor):
                                glColor4f(*color.getRgbF())
                            else:
                                glColor4f(*color)
                        else:
                            glEnableClientState(GL_COLOR_ARRAY)
                            glColorPointerf(color)

                        if norms is not None:
                            glEnableClientState(GL_NORMAL_ARRAY)
                            glNormalPointerf(norms)

                        if faces is None:
                            glDrawArrays(GL_TRIANGLES, 0, np.prod(verts.shape[:-1]))
                        else:
                            faces = faces.astype(np.uint32).flatten()
                            glDrawElements(GL_TRIANGLES, faces.shape[0], GL_UNSIGNED_INT, faces)
                    finally:
                        glDisableClientState(GL_NORMAL_ARRAY)
                        glDisableClientState(GL_VERTEX_ARRAY)
                        glDisableClientState(GL_COLOR_ARRAY)

            if self.opts['drawEdges']:
                verts = self.edgeVerts
                edges = self.edges
                glEnableClientState(GL_VERTEX_ARRAY)
                try:
                    glVertexPointerf(verts)

                    if self.edgeColors is None:
                        color = self.opts['edgeColor']
                        if isinstance(color, QtGui.QColor):
                            glColor4f(*color.getRgbF())
                        else:
                            glColor4f(*color)
                    else:
                        glEnableClientState(GL_COLOR_ARRAY)
                        glColorPointerf(color)
                    edges = edges.flatten()
                    glDrawElements(GL_LINES, edges.shape[0], GL_UNSIGNED_INT, edges)
                finally:
                    glDisableClientState(GL_VERTEX_ARRAY)
                    glDisableClientState(GL_COLOR_ARRAY)