   How to do logic operations to a integer texture in a fragment shader ?
  I need to do some logic operation to a render target which is a integer format texture.The process is to enable gl LogicOp, set the logic operation way to 'OR', and in fragment shader the output will do the logic operation with the corresponding value in the integer texture. So after the rendering, the integer texture will accumulate the results of every fragments covering this pixel.My question is, the output of fragment shader, gl_FragColor is a vec4, which is 4 float value.When I pack a integer value in the shader, like 0x0000100, how to make the integer value as the output value. Assign it to gl_FragColor will convert it to float format I think.I know in cg, one can define the return value's type like int4, but how to do this thing in glsl?thanks for your help.   