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//VTK::System::Dec
/*=========================================================================
Program: Visualization Toolkit
Module: vtkPointGaussianVS.glsl
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
// this shader implements imposters in OpenGL for Spheres
attribute vec4 vertexMC;
attribute vec2 offsetMC;
// optional normal declaration
//VTK::Normal::Dec
// Texture coordinates
//VTK::TCoord::Dec
// material property values
//VTK::Color::Dec
// clipping plane vars
//VTK::Clip::Dec
// camera and actor matrix values
//VTK::Camera::Dec
varying vec2 offsetVCVSOutput;
uniform int cameraParallel;
uniform float triangleScale;
void main()
{
//VTK::Color::Impl
//VTK::Normal::Impl
//VTK::TCoord::Impl
//VTK::Clip::Impl
// compute the projected vertex position
vec4 vertexVC = MCVCMatrix * vertexMC;
// the offsets sent down are positioned
// at 2.0*radius*triangleScale from the center of the
// gaussian. This has to be consistent
// with the offsets we build into the VBO
float radius = 0.5*sqrt(dot(offsetMC,offsetMC))/triangleScale;
// make the triangle face the camera
if (cameraParallel == 0)
{
vec3 dir = normalize(-vertexVC.xyz);
vec3 base2 = normalize(cross(dir,vec3(1.0,0.0,0.0)));
vec3 base1 = cross(base2,dir);
vertexVC.xyz = vertexVC.xyz + offsetMC.x*base1 + offsetMC.y*base2;
}
else
{
// add in the offset
vertexVC.xy = vertexVC.xy + offsetMC;
}
offsetVCVSOutput = offsetMC/radius;
gl_Position = VCDCMatrix * vertexVC;
}
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