[MacRuby-devel] Passing a string buffer to a C function

[Mike Taylor]

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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