pyGLV.GL.Shader

Shader classes

The Shader Compoment class is the dedicated to a specific type of data container in the pyECSS Component class that of assembling, using and destroying OpenGL API shader programs

Based on the Composite and Iterator design patterns:

• https://refactoring.guru/design-patterns/composite

• https://github.com/faif/python-patterns/blob/master/patterns/structural/composite.py

• https://refactoring.guru/design-patterns/iterator

• https://github.com/faif/python-patterns/blob/master/patterns/behavioral/iterator.py

class pyGLV.GL.Shader.Shader(name=None, type=None, id=None, vertex_source=None, fragment_source=None)

A concrete OpenGL-GLSL Shader container Component class

update()

method to be subclassed for debuging purposes only, in case we need some behavioral or logic computation within te Component. This violates the ECS architecture and should be avoided.

accept(system: pyECSS.System.System)

Accepts a class object to operate on the Component, based on the Visitor pattern.

Parameters

system ([System]) – [a System object]

init()

shader extra initialisation from raw strings or source file names

class pyGLV.GL.Shader.ShaderGLDecorator(comp, name=None, type=None, id=None)

A decorator of the Shader Compoment to decorate it with custom standard pass-through shader attributes

Parameters

ComponentDecorator ([type]) – [description]

init()

abstract method to be subclassed for extra initialisation

update()

method to be subclassed for debuging purposes only, in case we need some behavioral or logic computation within te Component. This violates the ECS architecture and should be avoided.

accept(system: pyECSS.System.System)

Accepts a class object to operate on the Component, based on the Visitor pattern.

Parameters

system ([System]) – [a System object]

class pyGLV.GL.Shader.InitGLShaderSystem(name=None, type=None, id=None, priority=0)

Initialise outside of the rendering loop RenderMesh, Shader, VertexArray, ShaderGLDecorator classes

init()

method to be subclassed for behavioral or logic computation when visits Components of an EntityNode.

update()

apply2RenderMesh(renderMesh: pyECSS.Component.RenderMesh)

method to be subclassed for behavioral or logic computation when visits Components.

apply2VertexArray(vertexArray: pyGLV.GL.VertexArray.VertexArray)

method to be subclassed for behavioral or logic computation when visits Components.

apply2Shader(shader: pyGLV.GL.Shader.Shader)

method to be subclassed for behavioral or logic computation when visits Components.

apply2ShaderGLDecorator(shaderGLDecorator: pyGLV.GL.Shader.ShaderGLDecorator)

method to be subclassed for behavioral or logic computation when visits Components.

class pyGLV.GL.Shader.RenderGLShaderSystem(name=None, type=None, id=None, priority=0)

A RenderSystem specifically for GL vertex and fragment Shaders and associated VertexArray components attached to a specific Entity

init()

method to be subclassed for behavioral or logic computation when visits Components of an EntityNode.

apply2VertexArray(vertexArray: pyGLV.GL.VertexArray.VertexArray)

Main GPU rendering is initiated when a vertexArray node is encountered and if a Shader/Shaderdecorator and RenderMesh components are present

method to be subclassed for behavioral or logic computation when visits RenderMesh Components of the parent EntityNode. Separate SystemDecorator is needed for each case, e.g. for rendering with GL vertex and fragment Shaders: RenderShaderSystem

Actuall RenderShaderSystem rendering is initiated in this update call, according to following pseudocode:

render(vertexArray: Optional[pyGLV.GL.VertexArray.VertexArray] = None, compRenderMesh: Optional[pyECSS.Component.RenderMesh] = None, compShader=None)

• Shader-based main draw():

  • retrive ShaderDecorator glid

  • useShaderProgram(ShaderDecorator.glid)

  • call ShaderDecorator::update to pass on uniform shader parameters to GPU

  • renderMeshVertexArray.execute(gl.GL_TRIANGLES)

  • userShaderProgram(0) #clean GL state