////////////////////////////////////////////////////////////
//
// SFML - Simple and Fast Multimedia Library
// Copyright (C) 2007-2009 Laurent Gomila (laurent.gom@gmail.com)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
////////////////////////////////////////////////////////////

#ifndef SFML_SHADER_H
#define SFML_SHADER_H

////////////////////////////////////////////////////////////
// Headers
////////////////////////////////////////////////////////////
#include <SFML/Graphics/Export.h>
#include <SFML/Graphics/Color.h>
#include <SFML/Graphics/Types.h>
#include <SFML/System/InputStream.h>


////////////////////////////////////////////////////////////
/// \brief Load both the vertex and fragment shaders from files
///
/// This function can load both the vertex and the fragment
/// shaders, or only one of them: pass NULL if you don't want to load
/// either the vertex shader or the fragment shader.
/// The sources must be text files containing valid shaders
/// in GLSL language. GLSL is a C-like language dedicated to
/// OpenGL shaders; you'll probably need to read a good documentation
/// for it before writing your own shaders.
///
/// \param vertexShaderFilename   Path of the vertex shader file to load, or NULL to skip this shader
/// \param fragmentShaderFilename Path of the fragment shader file to load, or NULL to skip this shader
///
/// \return A new sfShader object, or NULL if it failed
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API sfShader* sfShader_CreateFromFile(const char* vertexShaderFilename, const char* fragmentShaderFilename);

////////////////////////////////////////////////////////////
/// \brief Load both the vertex and fragment shaders from source codes in memory
///
/// This function can load both the vertex and the fragment
/// shaders, or only one of them: pass NULL if you don't want to load
/// either the vertex shader or the fragment shader.
/// The sources must be valid shaders in GLSL language. GLSL is
/// a C-like language dedicated to OpenGL shaders; you'll
/// probably need to read a good documentation for it before
/// writing your own shaders.
///
/// \param vertexShader   String containing the source code of the vertex shader, or NULL to skip this shader
/// \param fragmentShader String containing the source code of the fragment shader, or NULL to skip this shader
///
/// \return A new sfShader object, or NULL if it failed
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API sfShader* sfShader_CreateFromMemory(const char* vertexShader, const char* fragmentShader);

////////////////////////////////////////////////////////////
/// \brief Load both the vertex and fragment shaders from custom streams
///
/// This function can load both the vertex and the fragment
/// shaders, or only one of them: pass NULL if you don't want to load
/// either the vertex shader or the fragment shader.
/// The source codes must be valid shaders in GLSL language.
/// GLSL is a C-like language dedicated to OpenGL shaders;
/// you'll probably need to read a good documentation for
/// it before writing your own shaders.
///
/// \param vertexShaderStream   Source stream to read the vertex shader from, or NULL to skip this shader
/// \param fragmentShaderStream Source stream to read the fragment shader from, or NULL to skip this shader
///
/// \return A new sfShader object, or NULL if it failed
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API sfShader* sfShader_CreateFromStream(sfInputStream* vertexShaderStream, sfInputStream* fragmentShaderStream);

////////////////////////////////////////////////////////////
/// \brief Destroy an existing shader
///
/// \param shader Shader to delete
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_Destroy(sfShader* shader);

////////////////////////////////////////////////////////////
/// \brief Change a float parameter of a shader
///
/// \a name is the name of the variable to change in the shader.
/// The corresponding parameter in the shader must be a float
/// (float GLSL type).
///
/// Example:
/// \code
/// uniform float myparam; // this is the variable in the shader
/// \endcode
/// \code
/// sfShader_SetFloatParameter(shader, "myparam", 5.2f);
/// \endcode
///
/// \param shader Shader object
/// \param name   Name of the parameter in the shader
/// \param x      Value to assign
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_SetFloatParameter(sfShader* shader, const char* name, float x);

////////////////////////////////////////////////////////////
/// \brief Change a 2-components vector parameter of a shader
///
/// \a name is the name of the variable to change in the shader.
/// The corresponding parameter in the shader must be a 2x1 vector
/// (vec2 GLSL type).
///
/// Example:
/// \code
/// uniform vec2 myparam; // this is the variable in the shader
/// \endcode
/// \code
/// sfShader_SetFloat2Parameter(shader, "myparam", 5.2f, 6.0f);
/// \endcode
///
/// \param shader Shader object
/// \param name   Name of the parameter in the shader
/// \param x      First component of the value to assign
/// \param y      Second component of the value to assign
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_SetFloat2Parameter(sfShader* shader, const char* name, float x, float y);

////////////////////////////////////////////////////////////
/// \brief Change a 3-components vector parameter of a shader
///
/// \a name is the name of the variable to change in the shader.
/// The corresponding parameter in the shader must be a 3x1 vector
/// (vec3 GLSL type).
///
/// Example:
/// \code
/// uniform vec3 myparam; // this is the variable in the shader
/// \endcode
/// \code
/// sfShader_SetFloat3Parameter(shader, "myparam", 5.2f, 6.0f, -8.1f);
/// \endcode
///
/// \param shader Shader object
/// \param name   Name of the parameter in the shader
/// \param x      First component of the value to assign
/// \param y      Second component of the value to assign
/// \param z      Third component of the value to assign
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_SetFloat3Parameter(sfShader* shader, const char* name, float x, float y, float z);

////////////////////////////////////////////////////////////
/// \brief Change a 4-components vector parameter of a shader
///
/// \a name is the name of the variable to change in the shader.
/// The corresponding parameter in the shader must be a 4x1 vector
/// (vec4 GLSL type).
///
/// Example:
/// \code
/// uniform vec4 myparam; // this is the variable in the shader
/// \endcode
/// \code
/// sfShader_SetFloat4Parameter(shader, "myparam", 5.2f, 6.0f, -8.1f, 0.4f);
/// \endcode
///
/// \param shader Shader object
/// \param name   Name of the parameter in the shader
/// \param x      First component of the value to assign
/// \param y      Second component of the value to assign
/// \param z      Third component of the value to assign
/// \param w      Fourth component of the value to assign
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_SetFloat4Parameter(sfShader* shader, const char* name, float x, float y, float z, float w);

////////////////////////////////////////////////////////////
/// \brief Change a color parameter of a shader
///
/// \a name is the name of the variable to change in the shader.
/// The corresponding parameter in the shader must be a 4x1 vector
/// (vec4 GLSL type).
///
/// It is important to note that the components of the color are
/// normalized before being passed to the shader. Therefore,
/// they are converted from range [0 .. 255] to range [0 .. 1].
/// For example, a sf::Color(255, 125, 0, 255) will be transformed
/// to a vec4(1.0, 0.5, 0.0, 1.0) in the shader.
///
/// Example:
/// \code
/// uniform vec4 color; // this is the variable in the shader
/// \endcode
/// \code
/// sfShader_SetColorParameter(shader, "color", sfColor_FromRGB(255, 128, 0));
/// \endcode
///
/// \param shader Shader object
/// \param name   Name of the parameter in the shader
/// \param color  Color to assign
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_SetColorParameter(sfShader* shader, const char* name, sfColor color);

////////////////////////////////////////////////////////////
/// \brief Change a matrix parameter of a shader
///
/// \a name is the name of the variable to change in the shader.
/// The corresponding parameter in the shader must be a 4x4 matrix
/// (mat4 GLSL type).
///
/// Example:
/// \code
/// uniform mat4 matrix; // this is the variable in the shader
/// \endcode
/// \code
/// @todo
/// sfShader_SetTransformParameter(shader, "matrix", transform);
/// \endcode
///
/// \param shader    Shader object
/// \param name      Name of the parameter in the shader
/// \param transform Transform to assign
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_SetTransformParameter(sfShader* shader, const char* name, const sfTransform* transform);

////////////////////////////////////////////////////////////
/// \brief Change a texture parameter of a shader
///
/// \a name is the name of the variable to change in the shader.
/// The corresponding parameter in the shader must be a 2D texture
/// (sampler2D GLSL type).
///
/// Example:
/// \code
/// uniform sampler2D the_texture; // this is the variable in the shader
/// \endcode
/// \code
/// sf::Texture texture;
/// ...
/// sfShader_SetTextureParameter(shader, "the_texture", texture);
/// \endcode
/// It is important to note that \a texture must remain alive as long
/// as the shader uses it, no copy is made internally.
///
/// To use the texture of the object being draw, which cannot be
/// known in advance, you can use the special function
/// sfShader_SetCurrentTextureParameter:
/// \code
/// sfShader_SetCurrentTextureParameter(shader, "the_texture").
/// \endcode
///
/// \param shader  Shader object
/// \param name    Name of the texture in the shader
/// \param texture Texture to assign
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_SetTextureParameter(sfShader* shader, const char* name, const sfTexture* texture);

////////////////////////////////////////////////////////////
/// \brief Change a texture parameter of a shader
///
/// This function maps a shader texture variable to the
/// texture of the object being drawn, which cannot be
/// known in advance.
/// The corresponding parameter in the shader must be a 2D texture
/// (sampler2D GLSL type).
///
/// Example:
/// \code
/// uniform sampler2D current; // this is the variable in the shader
/// \endcode
/// \code
/// sfShader_SetCurrentTextureParameter(shader, "current");
/// \endcode
///
/// \param shader Shader object
/// \param name   Name of the texture in the shader
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_SetCurrentTextureParameter(sfShader* shader, const char* name);

////////////////////////////////////////////////////////////
/// \brief Bind a shader for rendering (activate it)
///
/// This function is normally for internal use only, unless
/// you want to use the shader with a custom OpenGL rendering
/// instead of a SFML drawable.
/// \code
/// sfWindow_SetActive(window, sfTrue);
/// sfShader_Bind(shader);
/// ... render OpenGL geometry ...
/// sfShader_Unbind(shader);
/// \endcode
///
/// \param shader Shader to bind
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_Bind(const sfShader* shader);

////////////////////////////////////////////////////////////
/// \brief Unbind a shader (deactivate it)
///
/// This function is normally for internal use only, unless
/// you want to use the shader with a custom OpenGL rendering
/// instead of a SFML drawable.
///
/// \param shader Shader to unbind
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API void sfShader_Unbind(const sfShader* shader);

////////////////////////////////////////////////////////////
/// \brief Tell whether or not the system supports shaders
///
/// This function should always be called before using
/// the shader features. If it returns false, then
/// any attempt to use sfShader will fail.
///
/// \return sfTrue if the system can use shaders, sfFalse otherwise
///
////////////////////////////////////////////////////////////
CSFML_GRAPHICS_API sfBool sfShader_IsAvailable(void);


#endif // SFML_SHADER_H