/*
 * Cogl
 *
 * An object oriented GL/GLES Abstraction/Utility Layer
 *
 * Copyright (C) 2011 Intel Corporation.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * Authors:
 *  Robert Bragg <robert@linux.intel.com>
 *
 */

#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
#error "Only <cogl/cogl.h> can be included directly."
#endif

#ifndef __COGL_DEPTH_STATE_H__
#define __COGL_DEPTH_STATE_H__

G_BEGIN_DECLS

/**
 * SECTION:cogl-depth-state
 * @short_description: Functions for describing the depth testing
 *                     state of your GPU.
 */

typedef struct
{
  guint32 COGL_PRIVATE (magic);

  gboolean COGL_PRIVATE (test_enabled);
  CoglDepthTestFunction COGL_PRIVATE (test_function);
  gboolean COGL_PRIVATE (write_enabled);
  float COGL_PRIVATE (range_near);
  float COGL_PRIVATE (range_far);

  guint32 COGL_PRIVATE (padding0);
  guint32 COGL_PRIVATE (padding1);
  guint32 COGL_PRIVATE (padding2);
  guint32 COGL_PRIVATE (padding3);
  guint32 COGL_PRIVATE (padding4);
  guint32 COGL_PRIVATE (padding5);
  guint32 COGL_PRIVATE (padding6);
  guint32 COGL_PRIVATE (padding7);
  guint32 COGL_PRIVATE (padding8);
  guint32 COGL_PRIVATE (padding9);

} CoglDepthState;

/**
 * cogl_depth_state_init:
 * @state: A #CoglDepthState struct
 *
 * Initializes the members of @state to their default values.
 *
 * You should never pass an un initialized #CoglDepthState structure
 * to cogl_pipeline_set_depth_state().
 *
 * Since: 2.0
 * Stability: Unstable
 */
void
cogl_depth_state_init (CoglDepthState *state);

/**
 * cogl_depth_state_set_test_enabled:
 * @state: A #CoglDepthState struct
 * @enable: The enable state you want
 *
 * Enables or disables depth testing according to the value of
 * @enable.
 *
 * If depth testing is enable then the #CoglDepthTestFunction set
 * using cogl_pipeline_set_depth_test_function() us used to evaluate
 * the depth value of incoming fragments against the corresponding
 * value stored in the current depth buffer, and if the test passes
 * then the fragments depth value is used to update the depth buffer.
 * (unless you have disabled depth writing via
 * cogl_pipeline_set_depth_writing_enabled ())
 *
 * By default depth testing is disabled.
 *
 * NB: this won't directly affect the state of the GPU. You have
 * to then set the state on a #CoglPipeline using
 * cogl_pipeline_set_depth_state()
 *
 * Since: 2.0
 * Stability: Unstable
 */
void
cogl_depth_state_set_test_enabled (CoglDepthState *state,
                                   gboolean enable);

/**
 * cogl_depth_state_get_test_enabled:
 * @state: A #CoglDepthState struct
 *
 * Gets the current depth test enabled state as previously set by
 * cogl_depth_state_set_test_enabled().
 *
 * Returns: The pipeline's current depth test enabled state.
 * Since: 2.0
 * Stability: Unstable
 */
gboolean
cogl_depth_state_get_test_enabled (CoglDepthState *state);

/**
 * cogl_depth_state_set_write_enabled:
 * @state: A #CoglDepthState struct
 * @enable: The enable state you want
 *
 * Enables or disables depth buffer writing according to the value of
 * @enable. Normally when depth testing is enabled and the comparison
 * between a fragment's depth value and the corresponding depth buffer
 * value passes then the fragment's depth is written to the depth
 * buffer unless writing is disabled here.
 *
 * By default depth writing is enabled
 *
 * NB: this won't directly affect the state of the GPU. You have
 * to then set the state on a #CoglPipeline using
 * cogl_pipeline_set_depth_state()
 *
 * Since: 2.0
 * Stability: Unstable
 */
void
cogl_depth_state_set_write_enabled (CoglDepthState *state,
                                    gboolean enable);

/**
 * cogl_depth_state_get_write_enabled:
 * @state: A #CoglDepthState struct
 *
 * Gets the depth writing enable state as set by the corresponding
 * cogl_pipeline_set_depth_writing_enabled.
 *
 * Returns: The current depth writing enable state
 * Since: 2.0
 * Stability: Unstable
 */
gboolean
cogl_depth_state_get_write_enabled (CoglDepthState *state);

/**
 * cogl_depth_state_set_test_function:
 * @state: A #CoglDepthState struct
 * @function: The #CoglDepthTestFunction to set
 *
 * Sets the #CoglDepthTestFunction used to compare the depth value of
 * an incoming fragment against the corresponding value in the current
 * depth buffer.
 *
 * By default the depth test function is %COGL_DEPTH_TEST_FUNCTION_LESS
 *
 * NB: this won't directly affect the state of the GPU. You have
 * to then set the state on a #CoglPipeline using
 * cogl_pipeline_set_depth_state()
 *
 * Since: 2.0
 * Stability: Unstable
 */
void
cogl_depth_state_set_test_function (CoglDepthState *state,
                                    CoglDepthTestFunction function);

/**
 * cogl_depth_state_get_test_function:
 * @state: A #CoglDepthState struct
 *
 * Gets the current depth test enable state as previously set via
 * cogl_pipeline_set_depth_test_enabled().
 *
 * Returns: The current depth test enable state.
 * Since: 2.0
 * Stability: Unstable
 */
CoglDepthTestFunction
cogl_depth_state_get_test_function (CoglDepthState *state);

/**
 * cogl_depth_state_set_range:
 * @state: A #CoglDepthState object
 * @near_val: The near component of the desired depth range which will be
 * clamped to the range [0, 1]
 * @far_val: The far component of the desired depth range which will be
 * clamped to the range [0, 1]
 *
 * Sets the range to map depth values in normalized device coordinates
 * to before writing out to a depth buffer.
 *
 * After your geometry has be transformed, clipped and had perspective
 * division applied placing it in normalized device
 * coordinates all depth values between the near and far z clipping
 * planes are in the range -1 to 1. Before writing any depth value to
 * the depth buffer though the value is mapped into the range [0, 1].
 *
 * With this function you can change the range which depth values are
 * mapped too although the range must still lye within the range [0,
 * 1].
 *
 * If your driver does not support this feature (for example you are
 * using GLES 1 drivers) then if you don't use the default range
 * values you will get an error reported when calling
 * cogl_pipeline_set_depth_state (). You can check ahead of time for
 * the %COGL_FEATURE_DEPTH_RANGE feature with
 * cogl_features_available() to know if this function will succeed.
 *
 * By default normalized device coordinate depth values are mapped to
 * the full range of depth buffer values, [0, 1].
 *
 * NB: this won't directly affect the state of the GPU. You have
 * to then set the state on a #CoglPipeline using
 * cogl_pipeline_set_depth_state().
 *
 * Since: 2.0
 * Stability: Unstable
 */
void
cogl_depth_state_set_range (CoglDepthState *state,
                            float near_val,
                            float far_val);

/**
 * cogl_depth_state_get_range:
 * @state: A #CoglDepthState object
 * @near_val: A pointer to store the near component of the depth range
 * @far_val: A pointer to store the far component of the depth range
 *
 * Gets the current range to which normalized depth values are mapped
 * before writing to the depth buffer. This corresponds to the range
 * set with cogl_pipeline_set_depth_range().
 *
 * Since: 2.0
 * Stability: Unstable
 */
void
cogl_depth_state_get_range (CoglDepthState *state,
                            float *near_val,
                            float *far_val);

G_END_DECLS

#endif /* __COGL_DEPTH_STATE_H__ */
