[MacRuby-devel] Passing a string buffer to a C function
Laurent Sansonetti
lsansonetti at apple.com
Wed May 5 13:39:56 PDT 2010
Hi Mike,
Thanks for the report. I think this is because GLchar* is typed in the runtime as a C-style string. The compiler should allow Pointer objects for this runtime type. Currently, it only allows nil, symbols and strings.
Could you file a bug? We will track this...
Thanks,
Laurent
On May 5, 2010, at 10:43 AM, Mike Taylor wrote:
>
> Hi all,
>
> I'm trying to do some GLSL shaders with MacRuby. However, I'm a bit stumped as to how to call glGetShaderInfoLog if the shader compilation fails. The C function's prototype is:
>
> void glGetShaderInfoLog(GLuint shader, GLsizei maxLength, GLsizei * length, GLchar * infoLog);
>
> I couldn't find any docs on how Pointer.new_with_type, so I tried a few things, such as:
>
> log_info = Pointer.new_with_type('c', 4096)
> length = Pointer.new_with_type('i')
>
> glGetShaderInfoLog(@shader_id, 4096, length, log_info)
>
> However, I get the error:
>
> TypeError: can't convert Pointer into String
>
> It seems that the bridge wants log_info to be a String object. But, using a String causes a bus error. I'm expecting that the bridge isn't expecting the string to be mutated.
>
> Any suggestions would be appreciated!
>
> /\/\ike
>
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> MacRuby-devel at lists.macosforge.org
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