MedicalVisualization

OpenGL Shader Documentation

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OpenGL supports shader programs through the following extensions:

The default vertex shader according to the above specification is: 

!!ARBvp1.0
OPTION ARB_position_invariant; 
MOV result.color,vertex.color; 
END

The default fragment shader according to the above specification is: 

!!ARBfp1.0
MOV result.color,fragment.color; 
END

The vertex shader supports the following assembler instructions: 

      Instruction    Inputs  Output   Description
      -----------    ------  ------   --------------------------------
      ABS            v       v        absolute value
      ADD            v,v     v        add
      ARL            s       a        address register load
      DP3            v,v     ssss     3-component dot product
      DP4            v,v     ssss     4-component dot product
      DPH            v,v     ssss     homogeneous dot product
      DST            v,v     v        distance vector
      EX2            s       ssss     exponential base 2
      EXP            s       v        exponential base 2 (approximate)
      FLR            v       v        floor
      FRC            v       v        fraction
      LG2            s       ssss     logarithm base 2
      LIT            v       v        compute light coefficients
      LOG            s       v        logarithm base 2 (approximate)
      MAD            v,v,v   v        multiply and add
      MAX            v,v     v        maximum
      MIN            v,v     v        minimum
      MOV            v       v        move
      MUL            v,v     v        multiply
      POW            s,s     ssss     exponentiate
      RCP            s       ssss     reciprocal
      RSQ            s       ssss     reciprocal square root
      SGE            v,v     v        set on greater than or equal
      SLT            v,v     v        set on less than
      SUB            v,v     v        subtract
      SWZ            v       v        extended swizzle
      XPD            v,v     v        cross product

The fragment shader supports the following assembler instructions: 

      Instruction    Inputs  Output   Description
      -----------    ------  ------   --------------------------------
      ABS            v       v        absolute value
      ADD            v,v     v        add
      CMP            v,v,v   v        compare
      COS            s       ssss     cosine with reduction to [-PI,PI]
      DP3            v,v     ssss     3-component dot product
      DP4            v,v     ssss     4-component dot product
      DPH            v,v     ssss     homogeneous dot product
      DST            v,v     v        distance vector
      EX2            s       ssss     exponential base 2
      FLR            v       v        floor
      FRC            v       v        fraction
      KIL            v       v        kill fragment
      LG2            s       ssss     logarithm base 2
      LIT            v       v        compute light coefficients
      LRP            v,v,v   v        linear interpolation
      MAD            v,v,v   v        multiply and add
      MAX            v,v     v        maximum
      MIN            v,v     v        minimum
      MOV            v       v        move
      MUL            v,v     v        multiply
      POW            s,s     ssss     exponentiate
      RCP            s       ssss     reciprocal
      RSQ            s       ssss     reciprocal square root
      SCS            s       ss--     sine/cosine without reduction
      SGE            v,v     v        set on greater than or equal
      SIN            s       ssss     sine with reduction to [-PI,PI]
      SLT            v,v     v        set on less than
      SUB            v,v     v        subtract
      SWZ            v       v        extended swizzle
      TEX            v,u,t   v        texture sample
      TXB            v,u,t   v        texture sample with bias
      TXP            v,u,t   v        texture sample with projection
      XPD            v,v     v        cross product

Assembler example: 

      TEMP a,b,c;
      ADD  c,a,b;

The above assembler statement adds the operands a and b (which are both 4 component vector registers) and stores the result in the destination register c. This involves 4 componentwise additions for all 4 components of the respective vector registers.

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