painter_header.hpp

Go to the documentation of this file.

/*!
 * \file painter_header.hpp
 * \brief file painter_header.hpp
 *
 * Copyright 2016 by Intel.
 *
 * Contact: kevin.rogovin@gmail.com
 *
 * This Source Code Form is subject to the
 * terms of the Mozilla Public License, v. 2.0.
 * If a copy of the MPL was not distributed with
 * this file, You can obtain one at
 * http://mozilla.org/MPL/2.0/.
 *
 * \author Kevin Rogovin <kevin.rogovin@gmail.com>
 *
 */
#ifndef FASTUIDRAW_PAINTER_HEADER_HPP
#define FASTUIDRAW_PAINTER_HEADER_HPP

#include <fastuidraw/util/util.hpp>
#include <fastuidraw/util/vecN.hpp>
#include <fastuidraw/util/c_array.hpp>

namespace fastuidraw
{
/*!\addtogroup PainterBackend
 * @{
 */

  /*!
   * \brief
   * A PainterHeader represents the values of the header for
   * the shaders to read to draw data. The header holds data
   * that is common for all vertices and fragments for an
   * item to draw, including with what shader and the data
   * for the shader.
   */
  class PainterHeader
  {
  public:
    enum
      {
        /*!
         * When \ref m_blend_shader_data_location is set to
         * \ref drawing_occluder, it indicates that the item
         * being drawing is an occluder thus the color
         * computation from the brush and item can be skipped.
         */
        drawing_occluder = ~0u,
      };

    /*!
     * \brief
     * Enumerations specifying how the contents of a PainterHeader
     * are packed into a data store buffer (PainterDraw::m_store),
     * offsets are in units of uint32_t (not \ref uvec4).
     */
    enum offset_t
      {
        clip_equations_location_offset, /*!< offset to \ref m_clip_equations_location */
        item_matrix_location_offset, /*!< offset to \ref m_item_matrix_location */
        brush_shader_data_location_offset, /*!< offset to \ref m_brush_shader_data_location */
        item_shader_data_location_offset, /*!< offset to \ref m_item_shader_data_location */
        blend_shader_data_location_offset, /*!< offset to \ref m_blend_shader_data_location */
        item_shader_offset, /*!< offset to \ref m_item_shader */
        brush_shader_offset, /*!< offset to \ref m_brush_shader */
        blend_shader_offset, /*!< offset to \ref m_blend_shader */
        z_offset, /*!< offset to \ref m_z */
        offset_to_deferred_coverage_x_offset, /*!< offset to \ref m_offset_to_deferred_coverage .x() */
        offset_to_deferred_coverage_y_offset, /*!< offset to \ref m_offset_to_deferred_coverage .y() */
        deferred_coverage_min_x_offset, /*!< offset to \ref m_deferred_coverage_min .x() */
        deferred_coverage_min_y_offset, /*!< offset to \ref m_deferred_coverage_min .y() */
        deferred_coverage_max_x_offset, /*!< offset to \ref m_deferred_coverage_max .x() */
        deferred_coverage_max_y_offset, /*!< offset to \ref m_deferred_coverage_max .y() */

        /*!
         * Offset to \ref m_brush_adjust_location
         */
        brush_adjust_location_offset,

        header_size /*!< size of header */
      };

    /*!
     * The offset, in units of uvec4 tuples, to the
     * location in the data store buffer (PainterDraw::m_store) for the
     * clip equations. I.e. the PainterClipEquations value is stored
     * (packed) at the location \code
     * PainterDraw::m_store[m_clip_equations_location]
     * \endcode
     */
    uint32_t m_clip_equations_location;

    /*!
     * The location, in units of uvec4 tuples, to the
     * location in the data store buffer (PainterDraw::m_store) for the
     * item matrix. I.e. the PainterItemMatrix value is stored (packed)
     * at the location
     * \code
     * PainterDraw::m_store[m_item_matrix_location]
     * \endcode
     */
    uint32_t m_item_matrix_location;

    /*!
     * The location, in units of uvec4 tuples, to the
     * location in the data store buffer (PainterDraw::m_store) for the
     * brush shader data. I.e. the data for a brush is stored (packed)
     * at the location
     * \code
     * PainterDraw::m_store[m_brush_shader_data_location]
     * \endcode
     */
    uint32_t m_brush_shader_data_location;

    /*!
     * The location, in units of uvec4 tuples, to the
     * location in the data store buffer (PainterDraw::m_store) for the
     * item shader data. I.e. the PainterItemShaderData value is stored
     * (packed) at the location
     * \code
     * PainterDraw::m_store[m_item_shader_data_location]
     * \endcode
     */
    uint32_t m_item_shader_data_location;

    /*!
     * The location, in units of uvec4 tuples, to the
     * location in the data store buffer (PainterDraw::m_store) for the
     * blend shader data. I.e. the PainterBlendShaderData value
     * is stored (packed) at the location
     * \code
     * PainterDraw::m_store[m_blend_shader_data_location]
     * \endcode
     * NOTE: if \ref m_blend_shader_data_location is \ref
     * drawing_occluder this means that the item being drawing
     * is an occluder thus the color computation from the brush
     * and item can be skipped.
     */
    uint32_t m_blend_shader_data_location;

    /*!
     * The ID of the item shader (i.e. PainterItemShader::ID()).
     */
    uint32_t m_item_shader;

    /*!
     * The ID of the brush shader (i.e. PainterBrushShader::ID()).
     */
    uint32_t m_brush_shader;

    /*!
     * The ID of the blend shader (i.e. PainterBlendShader::ID()).
     */
    uint32_t m_blend_shader;

    /*!
     * The z-value to use for the item. The z-value is used
     * by Painter to implement clipping and to prevent overdraw.
     * This is the value by which to increment the z-value of
     * the output of an item's vertex shader
     */
    int32_t m_z;

    /*!
     * Offset in pixels from where to read the deferred coverage
     * values.
     */
    ivec2 m_offset_to_deferred_coverage;

    /*!
     * Minimum value (in coverage buffer pixel coordinates)
     * from which allowed to read the coverage buffer.
     */
    ivec2 m_deferred_coverage_min;

    /*!
     * Maximum value (in coverage buffer pixel coordinates) from
     * which allowed to read the coverage buffer.
     */
    ivec2 m_deferred_coverage_max;

    /*!
     * If non-zero, indicates that the brush position is to be
     * adjusted in vertex shading before being fed the the brush
     * shading. When non-zero, is an offset, in units of
     * uvec4 tuples, to the location in the data
     * store buffer (PainterDraw::m_store) for the value encoded
     * by a \ref PainterBrushAdjust packed at the location
     * \code
     * PainterDraw::m_store[m_clip_equations_location]
     * \endcode
     */
    uint32_t m_brush_adjust_location;

    /*!
     * Pack the values of this PainterHeader
     * \param dst place to which to pack data
     */
    void
    pack_data(c_array<uvec4> dst) const;

    /*!
     * Returns the length of the data needed to encode the data.
     */
    static
    unsigned int
    data_size(void)
    {
      return FASTUIDRAW_NUMBER_BLOCK4_NEEDED(header_size);
    }
  };

/*! @} */
}

#endif