   skinning effect
  I am currently trying to perform a skinning effect with shader and I have a problem.Here is my shader:/*****************************************************************************/attribute vec3 vertices_coord;attribute vec4 vertices_color;attribute vec2 weight;//weight of each bonesattribute float numbones;//number of  bones treatedattribute vec2 indice;//indices for the matrixvarying vec4 color;void main(void){float i;mat4 bone[2];bone[0] = gl_ModelViewMatrix;bone[1] = mat4(1.0, 0.0, 0.0, 0.0,   0.0, 1.0, 0.0, 0.0,   0.0, 0.0, 1.0, 0.0,   0.0, 0.0, 0.0, 1.0);vec4 position = vec4(0.0, 0.0, 0.0, 0.0);vec2 weights = weight;vec2 index = indice;for( i=0.0; i< numbones; i+=1.0){position = position + weights.x*(bone[int(index.x)]*vec4(vertices_coord, 1.0));index = index.yx;weights = weights.yx;}gl_Position = position;color = vertices_color;}/*****************************************************************************/My problem comes from the position calculation.Indeed I cannot do bone[int(index.x)], it does not work, and I could not access the proper matrix...So I have a solution, I do a if in my loop on the index.x value, but I would like to know why I cannot access the proper matrix via this methods.   