static void compute_light_positions ( GLcontext * ctx ) [static]

Update state derived from light position, spot direction. Called upon: _NEW_MODELVIEW _NEW_LIGHT _TNL_NEW_NEED_EYE_COORDS

Update on (_NEW_MODELVIEW | _NEW_LIGHT) when lighting is enabled. Also update on lighting space changes.

Definition at line 1092 of file light.c.

Referenced by _mesa_update_tnl_spaces().

{
   struct gl_light *light;
   static const GLfloat eye_z[3] = { 0, 0, 1 };

   if (!ctx->Light.Enabled)
      return;

   if (ctx->_NeedEyeCoords) {
      COPY_3V( ctx->_EyeZDir, eye_z );
   }
   else {
      TRANSFORM_NORMAL( ctx->_EyeZDir, eye_z, ctx->ModelviewMatrixStack.Top->m );
   }

   foreach (light, &ctx->Light.EnabledList) {

      if (ctx->_NeedEyeCoords) {
         /* _Position is in eye coordinate space */
     COPY_4FV( light->_Position, light->EyePosition );
      }
      else {
         /* _Position is in object coordinate space */
     TRANSFORM_POINT( light->_Position, ctx->ModelviewMatrixStack.Top->inv,
              light->EyePosition );
      }

      if (!(light->_Flags & LIGHT_POSITIONAL)) {
     /* VP (VP) = Normalize( Position ) */
     COPY_3V( light->_VP_inf_norm, light->_Position );
     NORMALIZE_3FV( light->_VP_inf_norm );

     if (!ctx->Light.Model.LocalViewer) {
        /* _h_inf_norm = Normalize( V_to_P + <0,0,1> ) */
        ADD_3V( light->_h_inf_norm, light->_VP_inf_norm, ctx->_EyeZDir);
        NORMALIZE_3FV( light->_h_inf_norm );
     }
     light->_VP_inf_spot_attenuation = 1.0;
      }
      else {
         /* positional light w/ homogeneous coordinate, divide by W */
         GLfloat wInv = (GLfloat)1.0 / light->_Position[3];
         light->_Position[0] *= wInv;
         light->_Position[1] *= wInv;
         light->_Position[2] *= wInv;
      }

      if (light->_Flags & LIGHT_SPOT) {
     if (ctx->_NeedEyeCoords) {
        COPY_3V( light->_NormDirection, light->EyeDirection );
     }
         else {
        TRANSFORM_NORMAL( light->_NormDirection,
                  light->EyeDirection,
                  ctx->ModelviewMatrixStack.Top->m);
     }

     NORMALIZE_3FV( light->_NormDirection );

     if (!(light->_Flags & LIGHT_POSITIONAL)) {
        GLfloat PV_dot_dir = - DOT3(light->_VP_inf_norm,
                    light->_NormDirection);

        if (PV_dot_dir > light->_CosCutoff) {
           double x = PV_dot_dir * (EXP_TABLE_SIZE-1);
           int k = (int) x;
           light->_VP_inf_spot_attenuation =
          (GLfloat) (light->_SpotExpTable[k][0] +
           (x-k)*light->_SpotExpTable[k][1]);
        }
        else {
           light->_VP_inf_spot_attenuation = 0;
            }
     }
      }
   }
}

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