On 1 July 2013 20:40, kilon <[email protected]> wrote: > Thanks Igor , yes I was aware of String Cr because I have done some googling > around and it did find information on the subject. Apparently it failed > because I had an error in my source. > > So for our next challenge is learning how to fetch data that a pointer > points to. > > in this case I have an array that contains my vertex positions , called > vertexPositions > > 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 ) > > so far so good > > so I create a pointer for that array > > vptrsize := (NBExternalType sizeOf: 'float')* self vertexPositions size. > > and then take that pointer and insert in each position the individual values > from vertexPositions > > vertexPositions withIndexDo: [:each :i | > "using nbUInt32AtOffset because we know pointer is 4 bytes :) " > vpos nbFloat32AtOffset: (i-1)*(NBExternalType sizeOf: 'float') > put: > each value. > Transcript show: ' I am putting to vpos in index: '; show: i-1; show:' > value: '; show: each value; cr. > ]. > > so far so good. >
just one small advice: do not use #sizeOf: sparingly.. it parsing the type and doing full type resolution when you do that. you can remember the size of the type you need at boot/startup time, there is no chance it can change within same session :) but of course for demonstration purposes and readability it good. > now the tricky part is that I have a function that expects that Array , not > the smalltalk version but the C version we just created > > gl bufferData_target: GL_ARRAY_BUFFER size: vptrsize data: ....... usage: > GL_STATIC_DRAW. > > where you see the dots is where I should pass the data, in this case the C > array > > I could do a vpo nbFloat32AtOffset: but that will return me only the > individual value at the specific point (index) of the array, while I want to > pass the entire array. > > So how I do that ? > > I explored NBExternalAdress and I cant find something that would return an > array. Am I missing something obvious here ? > just pass NBExternalAdress instance as argument and you done. > NBExternalAdress value , returns the number of the address and not that data > contained in that address. > > I also see a NBExternalArray but I am not sure if it is what I should be > using . > arrayClass := NBExternalArray ofType: 'float'. array := arrayClass new: 5. "or externalNew:5 , if you want to allocate it in external memory" array at: 1 put: 10.1 "use just like normal Array" to pass it to function use: self soemFunction: array address. > Igor Stasenko wrote >> On 30 June 2013 21:11, kilon < > >> [email protected] > >> > wrote: >>> I am not going to post my code here cause it has become too big , you can >>> find it here >>> >>> http://www.smalltalkhub.com/#!/~kilon/GLTutorial >>> <http://www.smalltalkhub.com/#!/~kilon/GLTutorial> >>> >>> I tried adding newlines with String cr to my shaders strings, but >>> apparently >>> opengl is not convinced. It looks like smalltalk cr is not converted to C >>> "\n" newlines. So how I do that ? >>> >> >> simply replace all occurences of >> Character cr >> with >> Character lf >> (or crlf, if it wants that) >> >>> -- >>> View this message in context: >>> http://forum.world.st/Understanding-NBOpenGL-tp4686514p4696465.html >>> Sent from the Pharo Smalltalk Developers mailing list archive at >>> Nabble.com. >>> >> >> >> >> -- >> Best regards, >> Igor Stasenko. > > > > > > -- > View this message in context: > http://forum.world.st/Understanding-NBOpenGL-tp4686514p4696666.html > Sent from the Pharo Smalltalk Developers mailing list archive at Nabble.com. > -- Best regards, Igor Stasenko.
