GL Shader Program

Detailed Description

Class: kodi::gui::gl::CShaderProgram

Class to manage an OpenGL shader program
With this class the used GL shader code can be defined on the GPU and its variables can be managed between CPU and GPU.

It has the header #include <kodi/gui/gl/Shader.h> be included to enjoy it.

---

Example:

#include <kodi/gui/gl/Shader.h>
...
 
class ATTRIBUTE_HIDDEN CExample
  : ...,
    public kodi::gui::gl::CShaderProgram
{
public:
  CExample() = default;
 
  bool Start();
  void Render();
 
  // override functions for kodi::gui::gl::CShaderProgram
  void OnCompiledAndLinked() override;
  bool OnEnabled() override;
 
private:
  ...
  GLint m_aPosition = -1;
  GLint m_aColor = -1;
};
 
bool CExample::Start()
{
  // Define shaders and load
  std::string fraqShader = kodi::GetAddonPath("resources/shaders/" GL_TYPE_STRING "/glsl.frag");
  std::string vertShader = kodi::GetAddonPath("resources/shaders/" GL_TYPE_STRING "/glsl.vert");
  if (!LoadShaderFiles(vertShader, fraqShader) || !CompileAndLink())
    return false;
 
  ...
  return true;
}
 
...
 
void CExample::Render()
{
  ...
 
  EnableShader();
  ...
  DO WORK
  ...
  DisableShader();
}
 
void CExample::OnCompiledAndLinked()
{
  ...
  DO YOUR WORK HERE FOR WHAT IS ONE TIME REQUIRED DURING COMPILE OF SHADER, E.G.:
 
  m_aPosition = glGetAttribLocation(ProgramHandle(), "a_position");
  m_aColor = glGetAttribLocation(ProgramHandle(), "a_color");
}
 
bool OnEnabled() override
{
  ...
  DO YOUR WORK HERE FOR WHAT REQUIRED DURING ENABLE OF SHADER
  ...
  return true;
}
 
ADDONCREATOR(CExample);

Modules
	Child Functions
	Class: kodi::gui::gl::CShaderProgram child functions

Function Documentation

CShaderProgram() [1/2]

CShaderProgram ( )

default

Construct a new shader.

Load must be done later with LoadShaderFiles.

CShaderProgram() [2/2]

CShaderProgram ( const std::string &  vert, const std::string &  frag  )

inline

Construct a new shader and load defined shader files.

Parameters

[in]	vert	Path to used GL vertext shader
[in]	frag	Path to used GL fragment shader

~CShaderProgram()

virtual ~CShaderProgram ( )

inlinevirtual

Destructor.

LoadShaderFiles()

bool LoadShaderFiles ( const std::string &  vert, const std::string &  frag  )

inline

To load manually the needed shader files.

Parameters

[in]	vert	Path to used GL vertext shader
[in]	frag	Path to used GL fragment shader

Note

The use of the files is optional, but it must either be passed over here or via CompileAndLink, or both of the source code.

CompileAndLink()

bool CompileAndLink ( const std::string &  vertexExtraBegin = "", const std::string &  vertexExtraEnd = "", const std::string &  fragmentExtraBegin = "", const std::string &  fragmentExtraEnd = ""  )

inline

To compile and link the shader to the GL interface.

Optionally, additional source code can be transferred here, or it can be used independently without any files

Parameters

[in]	vertexExtraBegin	[opt] To additionally add vextex source code to the beginning of the loaded file source code
[in]	vertexExtraEnd	[opt] To additionally add vextex source code to the end of the loaded file source code
[in]	fragmentExtraBegin	[opt] To additionally add fragment source code to the beginning of the loaded file source code
[in]	fragmentExtraEnd	[opt] To additionally add fragment source code to the end of the loaded file source code

Returns

true if compile was successed

Note

In the case of a compile error, it will be written once into the Kodi log and in addition to the console output to quickly detect the errors when writing the damage.

EnableShader()

bool EnableShader ( )

inline

To activate the shader and use it on the GPU.

Returns

true if enable was successfull done

Note

During this call, the OnEnabled stored in the child is also called

DisableShader()

void DisableShader ( )

inline

To deactivate the shader use on the GPU.

ShaderOK()

ATTRIBUTE_FORCEINLINE bool ShaderOK ( ) const

inline

Used to check if shader has been loaded before.

Returns

true if enable was successfull done

Note

The CompileAndLink call sets these values

VertexShader()

ATTRIBUTE_FORCEINLINE CVertexShader& VertexShader ( )

inline

To get the vertex shader class used by Kodi at the addon.

Returns

pointer to vertex shader class

PixelShader()

ATTRIBUTE_FORCEINLINE CPixelShader& PixelShader ( )

inline

To get the fragment shader class used by Kodi at the addon.

Returns

pointer to fragment shader class

ProgramHandle()

ATTRIBUTE_FORCEINLINE GLuint ProgramHandle ( )

inline

Used to get the definition created in the OpenGL itself.

Returns

GLuint of GL shader program handler