# Source code for pyqtgraph.opengl.items.GLSurfacePlotItem

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

    from ..MeshData import MeshData
    from .GLMeshItem import GLMeshItem

    __all__ = ['GLSurfacePlotItem']

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

        Displays a surface plot on a regular x,y grid
        """
        def __init__(self, x=None, y=None, z=None, colors=None, **kwds):
            """
            The x, y, z, and colors arguments are passed to setData().
            All other keyword arguments are passed to GLMeshItem.__init__().
            """

            self._x = None
            self._y = None
            self._z = None
            self._color = None
            self._vertexes = None
            self._meshdata = MeshData()
            GLMeshItem.__init__(self, meshdata=self._meshdata, **kwds)

            self.setData(x, y, z, colors)

        def setData(self, x=None, y=None, z=None, colors=None):
            """
            Update the data in this surface plot.

            ==============  =====================================================================
            **Arguments:**
            x,y             1D arrays of values specifying the x,y positions of vertexes in the
                            grid. If these are omitted, then the values will be assumed to be
                            integers.
            z               2D array of height values for each grid vertex.
            colors          (width, height, 4) array of vertex colors.
            ==============  =====================================================================

            All arguments are optional.

            Note that if vertex positions are updated, the normal vectors for each triangle must
            be recomputed. This is somewhat expensive if the surface was initialized with smooth=False
            and very expensive if smooth=True. For faster performance, initialize with
            computeNormals=False and use per-vertex colors or a normal-independent shader program.
            """
            if x is not None:
                if self._x is None or len(x) != len(self._x):
                    self._vertexes = None
                self._x = x

            if y is not None:
                if self._y is None or len(y) != len(self._y):
                    self._vertexes = None
                self._y = y

            if z is not None:
                #if self._x is None:
                    #self._x = np.arange(z.shape[0])
                    #self._vertexes = None
                #if self._y is None:
                    #self._y = np.arange(z.shape[1])
                    #self._vertexes = None

                if self._x is not None and z.shape[0] != len(self._x):
                    raise Exception('Z values must have shape (len(x), len(y))')
                if self._y is not None and z.shape[1] != len(self._y):
                    raise Exception('Z values must have shape (len(x), len(y))')
                self._z = z
                if self._vertexes is not None and self._z.shape != self._vertexes.shape[:2]:
                    self._vertexes = None

            if colors is not None:
                self._colors = colors
                self._meshdata.setVertexColors(colors)

            if self._z is None:
                return

            updateMesh = False
            newVertexes = False

            ## Generate vertex and face array
            if self._vertexes is None:
                newVertexes = True
                self._vertexes = np.empty((self._z.shape[0], self._z.shape[1], 3), dtype=float)
                self.generateFaces()
                self._meshdata.setFaces(self._faces)
                updateMesh = True

            ## Copy x, y, z data into vertex array
            if newVertexes or x is not None:
                if x is None:
                    if self._x is None:
                        x = np.arange(self._z.shape[0])
                    else:
                        x = self._x
                self._vertexes[:, :, 0] = x.reshape(len(x), 1)
                updateMesh = True

            if newVertexes or y is not None:
                if y is None:
                    if self._y is None:
                        y = np.arange(self._z.shape[1])
                    else:
                        y = self._y
                self._vertexes[:, :, 1] = y.reshape(1, len(y))
                updateMesh = True

            if newVertexes or z is not None:
                self._vertexes[...,2] = self._z
                updateMesh = True

            ## Update MeshData
            if updateMesh:
                self._meshdata.setVertexes(self._vertexes.reshape(self._vertexes.shape[0]*self._vertexes.shape[1], 3))
                self.meshDataChanged()

        def generateFaces(self):
            cols = self._z.shape[1]-1
            rows = self._z.shape[0]-1
            faces = np.empty((cols*rows*2, 3), dtype=np.uint)
            rowtemplate1 = np.arange(cols).reshape(cols, 1) + np.array([[0, 1, cols+1]])
            rowtemplate2 = np.arange(cols).reshape(cols, 1) + np.array([[cols+1, 1, cols+2]])
            for row in range(rows):
                start = row * cols * 2
                faces[start:start+cols] = rowtemplate1 + row * (cols+1)
                faces[start+cols:start+(cols*2)] = rowtemplate2 + row * (cols+1)
            self._faces = faces