// VERTEX SHADER BODY
        code += "void main(void)\n";
        code += "{\n";
        // SKINNING
        if (options.skin) {
            code += "    mat4 modelMatrix = vertex_boneWeights.x * getBoneMatrix(vertex_boneIndices.x) +\n";
            code += "                       vertex_boneWeights.y * getBoneMatrix(vertex_boneIndices.y) +\n";
            code += "                       vertex_boneWeights.z * getBoneMatrix(vertex_boneIndices.z) +\n";
            code += "                       vertex_boneWeights.w * getBoneMatrix(vertex_boneIndices.w);\n";
            if (lighting) {
                code += "    mat3 normalMatrix = mat3(modelMatrix[0].xyz, modelMatrix[1].xyz, modelMatrix[2].xyz);\n";
            }
        } else {
            code += "    mat4 modelMatrix = matrix_model;\n";
            if (lighting) {
                code += "    mat3 normalMatrix = matrix_normal;\n";
            }
        }
        code += "\n";

        // TRANSFORM
        code += "    vec4 positionW = modelMatrix * vec4(vertex_position, 1.0);\n";
        code += "    gl_Position = matrix_viewProjection * positionW;\n\n";
        if (lighting) {
            code += "    vec3 normalW = normalMatrix * vertex_normal;\n";
            code += "    normalW = normalize(normalW);\n";
            if (options.normalMap && useTangents) {
                code += "    vec3 tangentW = normalMatrix * vertex_tangent.xyz;\n";
                code += "    tangentW  = normalize(tangentW);\n";
            }
        }
        code += "\n";

        // LIGHTING
        if (lighting) {
            if (options.normalMap && useTangents) {
                // Calculate the tangent space basis vectors
                code += "    vec3 binormalW = cross(normalW, tangentW) * vertex_tangent.w;\n";
                code += "    mat3 tbnMatrix = mat3(tangentW.x, binormalW.x, normalW.x,\n";
                code += "                          tangentW.y, binormalW.y, normalW.y,\n";
                code += "                          tangentW.z, binormalW.z, normalW.z);\n";
                code += "    vViewDirW = tbnMatrix * (view_position - positionW.xyz);\n";

                for (i = 0; i < totalLights; i++) {
                    if (i < totalDirs) {
                        code += "    vLight" + i + "DirW = -(tbnMatrix * light" + i + "_direction);\n";
                    }
                    if (i >= totalDirs) {
                        code += "    vLight" + i + "DirW = tbnMatrix * (light" + i + "_position - positionW.xyz);\n";
                    }
                    if (i >= totalDirs + totalPnts) {
                        code += "    vLight" + i + "SpotDirW = tbnMatrix * light" + i + "_spotDirection;\n";
                    }
                }
            } else {
                code += "    vNormalW = normalW;\n";
                code += "    vViewDirW = view_position - positionW.xyz;\n";

                for (i = 0; i < totalLights; i++) {
                    if (i < totalDirs) {
                        code += "    vLight" + i + "DirW = -light" + i + "_direction;\n";
                    }
                    if (i >= totalDirs) {
                        code += "    vLight" + i + "DirW = light" + i + "_position - positionW.xyz;\n";
                    }
                    if (i >= totalDirs + totalPnts) {
                        code += "    vLight" + i + "SpotDirW = light" + i + "_spotDirection;\n";
                    }
                }
            }