var
  z, x: integer;
  h: byte;
  y: single;
//***
for z := 0 to FHeightField.DimensionLength - 2 do
begin
  glBegin(GL_TRIANGLE_STRIP);
  for x := 0 to FHeightField.DimensionLength - 1 do
  begin
    h := FHeightField.GetValue(x, z);
    y := h * SCALE;
    glColor3ub(h, h, h);
    glVertex3f(x, y, z);

    h := FHeightField.GetValue(x, z + 1);
    y := h * SCALE;
    glColor3ub(h, h, h);
    glVertex3f(x, y, z + 1);
  end;
  glEnd;
end;