// Created on: 2013-10-10
// Created by: Denis BOGOLEPOV
// Copyright (c) 2013-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

//! @file Declarations.glsl
//! This files includes definition of common uniform variables in OCCT GLSL programs

//! @def THE_MAX_LIGHTS
//! Specifies the length of array of lights, which is 8 by default. Defined by Shader Manager.
// #define THE_MAX_LIGHTS 8

//! @def THE_MAX_CLIP_PLANES
//! Specifies the length of array of clipping planes, which is 8 by default. Defined by Shader Manager.
// #define THE_MAX_CLIP_PLANES 8

//! @def THE_NB_FRAG_OUTPUTS
//! Specifies the length of array of Fragment Shader outputs, which is 1 by default. Defined by Shader Manager.
// #define THE_NB_FRAG_OUTPUTS 1

// compatibility macros
#if (__VERSION__ >= 130)
  #define THE_ATTRIBUTE  in
  #define THE_SHADER_IN  in
  #define THE_SHADER_OUT out
  #define THE_OUT        out
  #define occTexture1D   texture
  #define occTexture2D   texture
  #define occTexture3D   texture
#else
  #define THE_ATTRIBUTE  attribute
  #define THE_SHADER_IN  varying
  #define THE_SHADER_OUT varying
  #define THE_OUT
  #define occTexture1D   texture1D
  #define occTexture2D   texture2D
  #define occTexture3D   texture3D
#endif

#ifdef GL_ES
  #define THE_PREC_ENUM lowp // enumerations should fit into lowp range
#else
  #define THE_PREC_ENUM
#endif

// Vertex attributes
#ifdef VERTEX_SHADER
  THE_ATTRIBUTE vec4 occVertex;
  THE_ATTRIBUTE vec3 occNormal;
  THE_ATTRIBUTE vec4 occTexCoord;
  THE_ATTRIBUTE vec4 occVertColor;
#elif defined(FRAGMENT_SHADER)
  #if (__VERSION__ >= 130)
    #ifdef OCC_ENABLE_draw_buffers
      out vec4 occFragColorArray[THE_NB_FRAG_OUTPUTS];
      #define occFragColorArrayAlias occFragColorArray
      #define occFragColor0 occFragColorArray[0]
    #else
      out vec4 occFragColor0;
    #endif
  #else
    #ifdef OCC_ENABLE_draw_buffers
      #define occFragColorArrayAlias gl_FragData
      #define occFragColor0 gl_FragData[0]
    #else
      #define occFragColor0 gl_FragColor
    #endif
  #endif

  #if (THE_NB_FRAG_OUTPUTS >= 2)
    #define occFragColor1 occFragColorArrayAlias[1]
  #else
    vec4 occFragColor1;
  #endif
  #if (THE_NB_FRAG_OUTPUTS >= 3)
    #define occFragColor2 occFragColorArrayAlias[2]
  #else
    vec4 occFragColor2;
  #endif
  #if (THE_NB_FRAG_OUTPUTS >= 4)
    #define occFragColor3 occFragColorArrayAlias[3]
  #else
    vec4 occFragColor3;
  #endif

  // Built-in outputs notation
  #define occFragColor    occFragColor0
  #define occFragCoverage occFragColor1

  //! Define the main Fragment Shader output - color value.
  void occSetFragColor (in vec4 theColor);
#endif

// Matrix state
uniform mat4 occWorldViewMatrix;  //!< World-view  matrix
uniform mat4 occProjectionMatrix; //!< Projection  matrix
uniform mat4 occModelWorldMatrix; //!< Model-world matrix

uniform mat4 occWorldViewMatrixInverse;    //!< Inverse of the world-view  matrix
uniform mat4 occProjectionMatrixInverse;   //!< Inverse of the projection  matrix
uniform mat4 occModelWorldMatrixInverse;   //!< Inverse of the model-world matrix

uniform mat4 occWorldViewMatrixTranspose;  //!< Transpose of the world-view  matrix
uniform mat4 occProjectionMatrixTranspose; //!< Transpose of the projection  matrix
uniform mat4 occModelWorldMatrixTranspose; //!< Transpose of the model-world matrix

uniform mat4 occWorldViewMatrixInverseTranspose;  //!< Transpose of the inverse of the world-view  matrix
uniform mat4 occProjectionMatrixInverseTranspose; //!< Transpose of the inverse of the projection  matrix
uniform mat4 occModelWorldMatrixInverseTranspose; //!< Transpose of the inverse of the model-world matrix

// light type enumeration
const int OccLightType_Direct = 1; //!< directional     light source
const int OccLightType_Point  = 2; //!< isotropic point light source
const int OccLightType_Spot   = 3; //!< spot            light source

// Light sources
uniform               vec4 occLightAmbient;      //!< Cumulative ambient color
#if defined(THE_MAX_LIGHTS) && (THE_MAX_LIGHTS > 0)
uniform THE_PREC_ENUM int  occLightSourcesCount; //!< Total number of light sources
int   occLight_Type              (in int theId); //!< Type of light source
int   occLight_IsHeadlight       (in int theId); //!< Is light a headlight?
vec4  occLight_Diffuse           (in int theId); //!< Diffuse intensity for specified light source
vec4  occLight_Specular          (in int theId); //!< Specular intensity (currently - equals to diffuse intencity)
vec4  occLight_Position          (in int theId); //!< Position of specified light source
vec4  occLight_SpotDirection     (in int theId); //!< Direction of specified spot light source
float occLight_ConstAttenuation  (in int theId); //!< Const attenuation factor of positional light source
float occLight_LinearAttenuation (in int theId); //!< Linear attenuation factor of positional light source
float occLight_SpotCutOff        (in int theId); //!< Maximum spread angle of the spot light (in radians)
float occLight_SpotExponent      (in int theId); //!< Attenuation of the spot light intensity (from 0 to 1)
#endif

// Front material properties accessors
vec4  occFrontMaterial_Emission(void);     //!< Emission color
vec4  occFrontMaterial_Ambient(void);      //!< Ambient  reflection
vec4  occFrontMaterial_Diffuse(void);      //!< Diffuse  reflection
vec4  occFrontMaterial_Specular(void);     //!< Specular reflection
float occFrontMaterial_Shininess(void);    //!< Specular exponent
float occFrontMaterial_Transparency(void); //!< Transparency coefficient

// Back material properties accessors
vec4  occBackMaterial_Emission(void);      //!< Emission color
vec4  occBackMaterial_Ambient(void);       //!< Ambient  reflection
vec4  occBackMaterial_Diffuse(void);       //!< Diffuse  reflection
vec4  occBackMaterial_Specular(void);      //!< Specular reflection
float occBackMaterial_Shininess(void);     //!< Specular exponent
float occBackMaterial_Transparency(void);  //!< Transparency coefficient

#define occActiveSampler    occSampler0                //!< alias for backward compatibility
#define occSamplerBaseColor occSampler0                //!< alias to a base color texture
uniform               sampler2D occSampler0;           //!< current active sampler;
                                                       //!  occSampler1, occSampler2,... should be defined in GLSL program body for multitexturing
uniform               vec4      occColor;              //!< color value (in case of disabled lighting)
uniform THE_PREC_ENUM int       occDistinguishingMode; //!< Are front and back faces distinguished?
uniform THE_PREC_ENUM int       occTextureEnable;      //!< Is texture enabled?
uniform               vec4      occTexTrsf2d[2];       //!< 2D texture transformation parameters
uniform               float     occPointSize;          //!< point size

//! Parameters of blended order-independent transparency rendering algorithm
uniform               int       occOitOutput;      //!< Enable bit for writing output color buffers for OIT (occFragColor, occFragCoverage)
uniform               float     occOitDepthFactor; //!< Influence of the depth component to the coverage of the accumulated fragment
uniform               float     occAlphaCutoff;    //!< alpha test cutoff value

//! Parameters of clipping planes
#if defined(THE_MAX_CLIP_PLANES) && (THE_MAX_CLIP_PLANES > 0)
uniform               vec4 occClipPlaneEquations[THE_MAX_CLIP_PLANES];
uniform THE_PREC_ENUM int  occClipPlaneCount;   //!< Total number of clip planes
#endif
