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/*
* File: BasicGaborShader.vert.txt
* Shader for drawing of basic parameterized gabor patches.
*
* This is the vertex shader. It takes the attributes (parameters)
* provided by the Screen('DrawTexture(s)') command, performs some
* basic calculations on it - the calculations that only need to be
* done once per gabor patch and that can be reliably carried out
* at sufficient numeric precision in a vertex shader - then it passes
* results of computations and other attributes as 'varying' parameters
* to the fragment shader.
*
* (c) 2007 by Mario Kleiner, licensed under MIT license.
*
*/
/* Constants that we need 2*pi and square-root of 2*pi: */
const float twopi = 2.0 * 3.141592654;
const float sqrtof2pi = 2.5066282746;
/* Conversion factor from degrees to radians: */
const float deg2rad = 3.141592654 / 180.0;
/* Texel position of center of gabor patch: Constant, set from Matlab */
/* once when the shader is created: */
uniform vec2 Center;
/* If disableNorm is set to 1.0, then the normalization term below is */
/* not applied to the gabors final values. Default is 0.0, ie. apply it. */
uniform float disableNorm;
/* Constant from setup code: Premultiply to contrast value: */
uniform float contrastPreMultiplicator;
/* Attributes passed from Screen(): See the ProceduralShadingAPI.m file for infos: */
attribute vec4 sizeAngleFilterMode;
attribute vec4 modulateColor;
attribute vec4 auxParameters0;
/* Information passed to the fragment shader: Attributes and precalculated per patch constants: */
varying float Angle;
varying vec4 baseColor;
varying float Phase;
varying float FreqTwoPi;
varying float Expmultiplier;
void main()
{
/* Apply standard geometric transformations to patch: */
gl_Position = ftransform();
/* Don't pass real texture coordinates, but ones corrected for hardware offsets (-0.5,0.5) */
/* and so that the center of the gabor patch has coordinate (0,0): */
gl_TexCoord[0] = gl_MultiTexCoord0 - vec4(Center, 0.0, 0.0) + vec4(-0.5, 0.5, 0.0, 0.0);
/* Contrast value is stored in auxParameters0[3]: */
float Contrast = auxParameters0[3];
/* Convert Angle and Phase from degrees to radians: */
Angle = deg2rad * sizeAngleFilterMode.z;
Phase = deg2rad * auxParameters0[0];
/* Precalc a couple of per-patch constant parameters: */
FreqTwoPi = auxParameters0[1] * twopi;
float SpaceConstant = auxParameters0[2];
Expmultiplier = -0.5 / (SpaceConstant * SpaceConstant);
/* Conditionally apply non-standard normalization term iff disableNorm == 0.0 */
float mc = disableNorm + (1.0 - disableNorm) * (1.0 / (sqrtof2pi * SpaceConstant));
/* Premultiply the wanted Contrast to the color: */
baseColor = modulateColor * mc * Contrast * contrastPreMultiplicator;
}
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