Igor got you will try to avoid using #sizeOf: , even for a readability I can replace it with a simple method returning the same thing depending in platform. Now because I am confused lets clarify how the whole things works because I see many errors in my code and clearly I don't understand how Nativeboost works. Note I am a C noob , so excuse me if I say anything stupid here. As far as functions call are concerned I see 3 possible scenariors a ) function(int var). Here the C function expects a simple variable of some type (int in this case) according to what you told me to make such variable I will do var := Nativeboost allocate:( NBExternalType typeof:'int') if I want to pass a value in that variable then I will do var nbInt32AtOffset: 0 put: 6 will call that function with Object function: var b) function(int* var) how I create the variable (pointer) ? how I put value in the variable (pointer) ? c) function( &var) Now I assume I will create a var variable same way as (a) var := Nativeboost allocate:( NBExternalType typeof:'int') but how I pass the address of var to the function ? I read the pdf of nativeboost but It did not clarify those things or simply I did not understand. Thanks on the instructions about NBExternalArray. So the reason of using this object is for convenience ? Igor Stasenko wrote
On 1 July 2013 20:40, kilon <
thekilon@.co
> 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 <
thekilon@.co
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)
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-- Best regards, Igor Stasenko.
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-- Best regards, Igor Stasenko.
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