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copied!<p>I got a typical 'vector4' class with an operator float* to autocast it for gl*4fv as well as []. There's also 'const' version for optimizations for the compiler as well as const refrences, and this works fine:</p> <pre><code>typedef struct vec4 { ... // ----------------------------------------------------------------- // // Cast operator, for [] inline operator float* () { return (float*)this; } // Const cast operator, for const [] inline operator const float* () const { return (const float*)this; } // ----------------------------------------------------------------- // ... // Vertex / Vector struct { float x, y, z, w; }; // Color struct { float r, g, b, a; }; } vec4; </code></pre> <p>My problem is when I now coded a 'matrix4' class, with operator vec4* which supports extracting rows from the matrix, and also have the 'side-effect' of having matrix[][] operator which is nice.</p> <pre><code>typedef struct mat4 { ... // ----------------------------------------------------------------- // // Cast operator, for [] inline operator vec4* () { return (vec4*)this; } // Const cast operator, for const [] inline operator const vec4* () const { return (const vec4*)this; } // ----------------------------------------------------------------- // private: float f[16]; } mat4; </code></pre> <p>My question is, why doesn't the compiler detect the ability to convert a mat4 to float*? I would suspect that the heritage of mat4 -> vec4 -> float* is reasonable, but it doesn't seem so. It came to my mind that the compiler might see it as mat4 -> vec4* -> float* which is not defined, but that assumption was invalid, since defining the operator</p> <pre><code>inline operator const vec4 () const { return (vec4)*this; } </code></pre> <p>does not work, and calling glMultMatrixf(mat4(...)); (for example) produces the same error message as without the operator.</p> <p>defining operator float* in mat4 is of course impossible, since that will eliminate the ability to use [][] (ambigious operators)</p> <p>Any solutions for this? or do I have to manually cast to vec4 everytime I want to autocast to float*? Auto-casting is a really nice feature and it interpolates the code with OpenGL neatly.</p>

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