GLTutorial1

'From Pharo3.0 of 18 March 2013 [Latest update: #30204] on 28 June 2013 at 3:08:01 pm'!
GLViewportMorph subclass: #GLTutorial1
    instanceVariableNames: 'gl theProgram positionBufferObject vertexPositions vertexShader fragmentShader vao'
    classVariableNames: ''
    poolDictionaries: ''
    category: 'GLTutorial'!
!GLTutorial1 commentStamp: '<historical>' prior: 0!
First tutorial showing basic functionality of NBOpengl

In this tutorial we show how to draw a triangle . The tutorial follows the tutorial here -> http://www.arcsynthesis.org/gltut/Basics/Tut01%20Dissecting%20Display.html
!


!GLTutorial1 methodsFor: 'as yet unclassified' stamp: 'kilon 6/28/2013 14:56'!
checkShaderError: aShader
    "check shader for any opengl compiler errors"
    "|statusAdress|
    statusAdress := NativeBoost allocate:  NBOpenGLTypes GLint.
    gl getShaderiv_shader: shader pname: GL_INFO_LOG_LENGTH params: statusAdress .
    statusAdress  = GL_FALSE ifTrue: [  ]"

| len status statusPtr lenPtr logPtr  statusPtrValue glValue gltrue|
    len := GL_INFO_LOG_LENGTH.
    status:= GL_COMPILE_STATUS.
    statusPtr := NativeBoost allocate: (NBExternalType sizeOf: 'int').
    "statusPtr nbUInt64AtOffset: 0 put: 0."
    gltrue  := GL_TRUE.
    self halt.
    gl getShaderiv_shader: aShader pname: status params: statusPtr.
    statusPtrValue := statusPtr value.
    glValue := GL_FALSE.
    self halt.
    (statusPtrValue = GL_FALSE) ifTrue: [
        lenPtr := NativeBoost allocate: (NBExternalType sizeOf: 'GLint').
        gl getShaderiv_shader: aShader pname: len  params: lenPtr.

        logPtr := NativeBoost allocate: (NBExternalType sizeOf: 'char') * (lenPtr+1).
        gl getShaderInfoLog_shader: aShader bufSize:lenPtr length: 0 infoLog: logPtr.

        Transcript show: logPtr.

        statusPtr free.
        lenPtr free.
        logPtr free.
    ]  ifFalse: [Transcript show: 'Compile OK'; cr].





    ! !

!GLTutorial1 methodsFor: 'as yet unclassified' stamp: 'kilon 6/23/2013 17:40'!
glVersion
"returns the version of Opengl used by NBOpenGL"
    ^ (gl getString: GL_VERSION) readString .! !

!GLTutorial1 methodsFor: 'as yet unclassified' stamp: 'kilon 6/26/2013 11:56'!
glerror
    "comment stating purpose of message"

    ^ gl getError ! !


!GLTutorial1 methodsFor: 'Program' stamp: 'kilon 6/23/2013 17:41'!
createProgram: shaderList
    "links shaders to the program"

    | program |
    program := gl createProgram .

    shaderList do: [ :each| gl attachShader_program: program shader: each  ].
    gl linkProgram:  program.

    shaderList do: [:each| gl detachShader_program: program shader: each ].

    ^ program


    ! !


!GLTutorial1 methodsFor: 'shaders' stamp: 'kilon 6/27/2013 21:57'!
createShader: shaderType string: shaderString

    " create shader using its source and compile it , return shader"

    | sources sizeOfPointer externalArrayOfPointers sourcesOnHeap shader |

    shader := gl createShader: shaderType .

    sources := shaderString .

    sizeOfPointer := NBExternalType sizeOf: 'void*'.

    "allocate buffer for array of pointers"
    externalArrayOfPointers := NativeBoost allocate: sizeOfPointer * sources size.

    "allocate strings and copy them to external heap"
    sourcesOnHeap := sources collect: [:each | NBExternalAddress fromString: each ].

    "copy string pointers to external array"
    sourcesOnHeap withIndexDo: [:ptr :i |
       "using nbUInt32AtOffset because we know pointer is 4 bytes :) "
            externalArrayOfPointers nbUInt32AtOffset: (i-1)*4 put: ptr value
    ].

    gl shaderSource_shader: shader count:  sources size  string:
    externalArrayOfPointers
     length: (NBExternalAddress null) .



    gl compileShader: shader.

    self checkShaderError: shader.

    "but after, don't forget to free the memory:"
    sourcesOnHeap do: [:each | each free].
    externalArrayOfPointers free.

    ^ shader! !

!GLTutorial1 methodsFor: 'shaders' stamp: 'kilon 6/27/2013 21:36'!
fragmentShader
    "fragment shader source"
^#('#version 110\n'
    'out vec4 outputColor;\n'
    'void main()\n'
    '{ \n'
    '  outputColor = vec4(1.0f, 1.0f ,1.0f , 1.0f);\n'
    '}\n')! !

!GLTutorial1 methodsFor: 'shaders' stamp: 'kilon 6/28/2013 14:03'!
vertexShader
    "vertex shader source code"
^# ('#version 110\n'
    'layout(location = 0) in vec4 position;\n'
    'void main()\n'
    '{\n'
      'gl_Position = position and blah blah blah\n'
    '}\n')! !


!GLTutorial1 methodsFor: 'instance variables' stamp: 'kilon 6/23/2013 17:44'!
display
"returns opengl context"
    ^ display! !

!GLTutorial1 methodsFor: 'instance variables' stamp: 'kilon 6/9/2013 17:09'!
gl
    ^display gl! !

!GLTutorial1 methodsFor: 'instance variables' stamp: 'kilon 6/23/2013 17:42'!
vao
    "vertex array"

    ^ 0! !

!GLTutorial1 methodsFor: 'instance variables' stamp: 'kilon 6/23/2013 17:42'!
vertexPositions
"the positions of vertices to be passed to opengl"

    ^ #( 0.75  0.75 0.0 1.0 0.75  -0.75 0.0 1.0 -0.75 -0.75 0.0 1.0 )! !


!GLTutorial1 methodsFor: 'initialisation' stamp: 'scorpion81 6/27/2013 18:32'!
initialiseVertexBuffer
"initialise Buffers"

    "| externalInt |"
    |externalInt vpos vptrsize |

    positionBufferObject := (NBExternalType sizeOf: 'float') * 12.
    vptrsize := positionBufferObject.
    externalInt := NativeBoost allocate: (NBExternalType sizeOf: 'int').
    externalInt nbInt32AtOffset: 0 put: positionBufferObject .

    gl genBuffers_n:  1 buffers: externalInt .
    gl bindBuffer_target: GL_ARRAY_BUFFER buffer: positionBufferObject .

    vpos := NativeBoost allocate: vptrsize.
    vertexPositions withIndexDo: [:ptr :i |
       "using nbUInt32AtOffset because we know pointer is 4 bytes :) "
            vpos nbFloat32AtOffset: (i-1)*(NBExternalType sizeOf: 'float') put: ptr value
    ].


    gl bufferData_target: GL_ARRAY_BUFFER size: positionBufferObject data: vpos usage: GL_STATIC_DRAW.
    gl bindBuffer_target: GL_ARRAY_BUFFER buffer:  0.

    externalInt free.
    vpos free.

! !

!GLTutorial1 methodsFor: 'initialisation' stamp: 'scorpion81 6/27/2013 18:11'!
initialize

    super initialize.

    gl := self gl.
    vertexShader := self vertexShader .
    fragmentShader := self fragmentShader .
    vao := self vao.
    vertexPositions := self vertexPositions .

    self initializeProgram .
    self initialiseVertexBuffer.

    "gl genVertexArrays_n: 1 arrays: vao.
    gl bindVertexArray: vao."



    ! !

!GLTutorial1 methodsFor: 'initialisation' stamp: 'kilon 6/27/2013 21:42'!
initializeProgram
    "create each shader and program"

    | shaderList strVertexShader strFragmentShader |

    strVertexShader  := self createShader: GL_VERTEX_SHADER string:  ( self vertexShader ).
    strFragmentShader  := self createShader:  GL_FRAGMENT_SHADER string: (self fragmentShader).
    shaderList := {strVertexShader. strFragmentShader}.
    theProgram := self createProgram:  shaderList .
    shaderList do: [ :each | gl deleteShader: each  ].
! !


!GLTutorial1 methodsFor: 'display' stamp: 'kilon 6/27/2013 21:30'!
render
"handles the rendering of the context"

    | externalInt |

    gl clearColor_red: 0.0 green: 0.7  blue: 1.0  alpha: 1.0  .
    gl clear: GL_COLOR_BUFFER_BIT.
    gl enable: GL_MULTISAMPLE_ARB.

    gl useProgram: theProgram .

    gl bindBuffer_target: GL_ARRAY_BUFFER buffer:  positionBufferObject .
    gl enableVertexAttribArray: 0.

    "externalInt := NativeBoost allocate: (NBExternalType sizeOf: 'int')."
    "externalInt nbInt32AtOffset: 0 put: 0."
    externalInt := (NBExternalAddress null).

    gl vertexAttribPointer_index: 0 size: 4  type:  GL_FLOAT normalized: GL_FALSE stride: 0  pointer: 0.

    "externalInt free."

    gl drawArrays_mode: GL_TRIANGLES first: 0  count: 3.

    gl disableVertexAttribArray:  0.
    gl useProgram: 0.! !