Le 03/10/2013 11:23, Patrice Colet a écrit : > Hello, > > I'm trying to find out how to get a backbuffer for attached shader found in > the web (http://glsl.heroku.com/e#8849.0), it seem I couldn't get alpha > channel in gemframebuffer's recursion, any idea? > > Colet Patrice > > > > _______________________________________________ > Pd-list@iem.at mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list Hello Patrice,
I just added a line at the begining and an other one at the end of fractalFeedback.frag to change the alpha for the feedback. I also change the texunit ID backbuffer to 0 in the patch. You can change alpha feedback with the number box i added in the patch. Hope it helps. ++ Jack
feedback.pd
Description: application/puredata
uniform float time, alpha_back;
uniform vec2 mouse;
uniform vec2 resolution;
uniform sampler2D backbuffer;
#define PI2 6.2831853070
// definition for a scale, rotate, and color transform
// color transform is multiply (darken) only
struct Transform {
vec4 color;
vec2 center;
float scale;
float rotation;
};
vec2 applyTransform(const Transform t, vec2 v) {
v -= t.center;
float c = cos(t.rotation);
float s = sin(t.rotation);
return (vec2(
(v.x*c - v.y*s),
(v.y*c + v.x*s)) * t.scale + t.center);
}
#define SCALE 5.0
// model will be scaled such that the rectangle (-SCALE/2, -SCALE/2), (SCALE/2,
SCALE/2)
// will be centered and fit the window with square aspect ratio.
float scale = SCALE / min(resolution.y,resolution.x);
vec2 mapModelToTexture(const vec2 v) {
return (v/(resolution*scale) + 0.5);
}
vec2 mapTextureToModel(const vec2 v) {
return (v - 0.5 * resolution) * scale;
}
// apply transform, return backbuffer sample
vec4 getBackbufferTransform(const Transform t, vec2 v) {
return t.color *
texture2D(backbuffer,
mapModelToTexture(applyTransform(t, v)));
}
vec4 whiten(const vec4 color, float f) {
return (1.-f)*color + vec4(f);
}
void main( void ) {
// transform fragment coords to model coords
vec2 v = mapTextureToModel(gl_FragCoord.xy);
// draw orbs
const float innerRadius = 0.01;
float outerRadius = .24 + .03 * (sin(17.*time) + sin(11.*time));
vec2 p1 = (vec2(sin(time), cos(time)));
vec2 p2 = (vec2(sin(time*1.1), cos(time*1.1)));
vec2 p3 = (vec2(sin(time*1.3), cos(time*1.3)));
float d1 = length(v -p1);
float d2 = length(v -p2);
float d3 = length(v -p3);
const float aa = 0.95;
const float bb = 0.65;
const float cc = 0.05;
const vec4 color1 = vec4(aa, bb, cc, 2.0);
const vec4 color2 = vec4(cc, bb, aa, 2.0);
const vec4 color3 = vec4(aa, cc, bb, 2.0);
vec4 drawing = vec4(0.,0.,0.,0.);
drawing += smoothstep(outerRadius, innerRadius, d1) * color1;
drawing += smoothstep(outerRadius, innerRadius, d2) * color2;
drawing += smoothstep(outerRadius, innerRadius, d3) * color3;
// draw ring/disc
float rr = length(v);
drawing += vec4(1.)
* smoothstep(1.1, 1., rr)
* smoothstep(0.9, 0.5+0.5*sin(0.1*time), rr);
// apply feedback transforms to backbuffer
// define transform structs
float r = time*.27;
Transform t1 = Transform(
whiten(vec4(aa, bb, cc, 1.0), 0.7),
vec2(-.7, 0.),
1.5,
-r*3.);
Transform t2 = Transform(
whiten(vec4(cc, bb, aa, 1.0), 0.7),
vec2(0.7, 0.),
1.5,
r*2.);
// composite feedback with drawing
vec4 fc = max( getBackbufferTransform(t1, v),
getBackbufferTransform(t2, v));
gl_FragColor = (1.-drawing[3])*fc -vec4(.01) + drawing[3]*drawing;
gl_FragColor.a = alpha_back;
}
// Cyrille Henry 2007
void main()
{
gl_TexCoord[0] = gl_MultiTexCoord0;
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}
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