Load float array with 3D texture?

Question

i have a float array with intensity value, i need load this array as 3d texture in opengl, and in the fragment shader read this as red color (float sample= texture(cord,volumeText).r). the size of array is 256*256*256, and the intensity value are between 0.0 to 256.0.

this is a sample of intensity values:

   75.839354473071637,     
   64.083049468866022,    
   65.253933716444365,     
   79.992431196592577,     
   84.411485976957096,     
   0.0000000000000000,     
   82.020319431382831,     
   76.808403454586994,     
   79.974774618246158,     
   0.0000000000000000,     
   91.127273013466336,     
   84.009956557448433,     
   90.221356094672814,     
   87.567422484025627,     
   71.940263118478072,     
   0.0000000000000000,     
   0.0000000000000000,     
   74.487058398181944,
   ..................,
   ..................

Answer 1

To load a texture like this you can use the input format GL_RED and type GL_FLOAT. A proper sized internal format for is GL_R16F. See glTexImage3D:

glTexImage3D(GL_TEXTURE_3D, 0, GL_R16F, 256, 256, 256, 0, GL_RED, GL_FLOAT, dataPtr)

The internal format GL_R16F is a floating point format. This means when you read the red color channel (.r) from the texture in the fragment shader, then the values are still in range [0.0, 256.0].