1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
/*=========================================================================
Program: Visualization Toolkit
Module: vtkGPUVolumeRayCastMapper_MIPCroppingFS.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.
=========================================================================*/
// Implementation of some functions used by the Maximum Intensity Projection
// (MIP) method when cropping is on.
#version 110
// GLSL Spec 1.10 rev 59 30-April-2004 defines gl_FragData[] but implementation
// older than the spec only has it as an extension
// (nVidia Linux driver 100.14.13, OpenGL version 2.1.1,
// on Quadro FX 3500/PCI/SSE2)
#extension GL_ARB_draw_buffers : enable
// max scalar buffer as an input
uniform sampler2D scalarBufferTexture;
// 2D Texture fragment coordinates [0,1] from fragment coordinates
// the scalar frame buffer texture has the size of the plain buffer but
// we use a fraction of it. The texture coordinates is less than 1 if
// the reduction factor is less than 1.
vec2 fragTexCoord;
float initialMaxValue()
{
return texture2D(scalarBufferTexture,fragTexCoord).r;
}
void writeColorAndMaxScalar(vec4 sample,
vec4 opacity,
float maxValue)
{
// color framebuffer
gl_FragData[0].r =sample.r * opacity.a;
gl_FragData[0].g =sample.g * opacity.a;
gl_FragData[0].b =sample.b * opacity.a;
gl_FragData[0].a=opacity.a;
// max scalar framebuffer
gl_FragData[1].r=maxValue;
gl_FragData[1].g=0.0;
gl_FragData[1].b=0.0;
gl_FragData[1].a=0.0;
}
|
