/usr/share/imagevis3d/shaders/GLRaycaster-ISO-CV-FS.glsl is in imagevis3d 3.1.0-6.
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For more information, please see: http://software.sci.utah.edu
The MIT License
Copyright (c) 2008 Scientific Computing and Imaging Institute,
University of Utah.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/
/**
\file GLRaycaster-ISO-CV-FS.glsl
\author Jens Krueger
SCI Institute
University of Utah
\version 1.0
\date October 2008
*/
uniform sampler2D texRayExitPos; ///< the backface (or ray exit point) texture in eyecoords
uniform sampler2D texLastHit; ///< the texcoords hit + ray param from the first pass
uniform sampler2D texLastHitPos; ///< the worldspace pos + tile ID from the first pass
uniform vec3 vVoxelStepsize; ///< Stepsize (in texcoord) to get to the next voxel
uniform float fRayStepsize; ///< stepsize along the ray
uniform float fIsoval; ///< the isovalue
uniform vec2 vScreensize; ///< the size of the screen in pixels
uniform vec2 vProjParam; ///< X = far / (far - near) / Y = (far * near / (near - far))
uniform int iTileID; ///< ID of the current tile
uniform vec3 vDomainScale;
varying vec3 vEyePos;
vec4 sampleVolume(vec3 coords);
vec3 ComputeNormal(vec3 vHitPosTex, vec3 StepSize,
vec3 DomainScale);
vec3 RefineIsosurface(in vec3 vRayDir,
inout vec3 vCurrentPos,
in float fIsoval);
void main(void)
{
// compute the coordinates to look up the previous pass
vec2 vFragCoords = vec2(gl_FragCoord.x / vScreensize.x , gl_FragCoord.y / vScreensize.y);
// compute the ray parameters
vec3 vRayEntry = texture2D(texRayExitPos, vFragCoords).xyz;
vec3 vRayExit = vEyePos;
vec3 vRayEntryTex = (gl_TextureMatrix[0] * vec4(vRayEntry,1.0)).xyz;
vec3 vRayExitTex = (gl_TextureMatrix[0] * vec4(vRayExit,1.0)).xyz;
// if in the first iso pass we found a hit in the same tile as we are processing now
// we can start from the last position
float fLastTileID = texture2D(texLastHitPos, vFragCoords).w;
if (float(iTileID) == fLastTileID) {
// update entry point to last stop
float fLastHitParam = texture2D(texLastHit, vFragCoords).w;
vRayEntry = vRayEntry * (1.0-fLastHitParam) + vRayEntry * fLastHitParam;
vRayEntryTex = vRayEntryTex * (1.0-fLastHitParam) + vRayExitTex * fLastHitParam;
}
float fRayLength = length(vRayExit - vRayEntry);
float fRayLengthTex = length(vRayExitTex - vRayEntryTex);
// compute the maximum number of steps before the domain is left
int iStepCount = int(fRayLength/fRayStepsize)+1;
vec3 vRayIncTex = (vRayExitTex-vRayEntryTex)/(fRayLength/fRayStepsize);
// do the actual raycasting
vec4 vHitPosTex = vec4(0.0,0.0,0.0,0.0);
vec3 vCurrentPosTex = vRayEntryTex;
for (int i = 0;i<iStepCount;i++) {
float fVolumVal = sampleVolume(vCurrentPosTex).x;
if (fVolumVal >= fIsoval) {
vHitPosTex = vec4(vCurrentPosTex.x, vCurrentPosTex.y, vCurrentPosTex.z, 1);
break;
}
vCurrentPosTex += vRayIncTex;
}
// store surface hit if one is found
if (vHitPosTex.a != 0.0)
vHitPosTex.xyz = RefineIsosurface(vRayIncTex, vHitPosTex.xyz, fIsoval);
else
discard;
// interpolate eye space position
float fInterpolParam = length(vHitPosTex.xyz-vRayEntryTex)/fRayLengthTex;
vec3 vHitPos = vRayEntry * (1.0-fInterpolParam) + vRayExit * fInterpolParam;
gl_FragData[0] = vec4(vHitPos.xyz,fInterpolParam);
// store non-linear depth
gl_FragDepth = vProjParam.x + (vProjParam.y / -vEyePos.z); // as the surface maybe transparent set depth to the ray exit pos, so we get at least the bbox correct
// store normal
vec3 vNormal = ComputeNormal(vHitPosTex.xyz, vVoxelStepsize,
vDomainScale);
gl_FragData[1] = vec4(vNormal,float(iTileID));
}
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