Re: Dynamic change of glshader element (Dušan Poizl)

[Christian Winkler]

Thanks!

What is "shader" in your example?
How can i access taht in native code?
Im am setting up the element like this:

GstElement *distortion;
distortion = gst_element_factory_make ("glshader","glshader");

Kind regards
Christian





change it to uniform variable. "uniform vec2 leftCenter;"

then you should be able to change it with gst_gl_shader_set_uniform_2f(shader, "leftCenter", x, y);

Dňa 15.11.2014 o 11:10 Christian Winkler napísal(a):
>
> Dear Members,
>
>  
>
> i am trying to change a glshader element at runtime in a native 
> Gstreamer application.
>
>  
>
> The idea is to convert a rtsp Stream to an side-by-side view for a 
> android google cardboard VR device.
>
> I want to implement headtracking as well and therefore want to change 
> the opengl fragment dynamically based on head position.
>
>  
>
> The code below works for a static .frag file.
>
>  
>
> QUESTION: How can i change for example
>
> _const_vec2 leftCenter = vec2(0.25, 0.4);
>
> _const_vec2 rightCenter = vec2(0.75, 0.4);
>
> DYNAMICALLY during runtime in the native code?
>
>  
>
> There used tob o something like gstglfiltershader, but i can not find 
> a similar functionality in the current 1.4.x releases.
>
>  
>
> Thanks!!!!
>
> Kind regards
>
> Christian
>
>  
>
>  
>
> The current Pipeline is set up as follows (JNI Code for an Android App).
>
> This
>
>  
>
>  
>
>                 ….
>
>                 // rtspsrc location=rtsp://192.168.137.240:8554/test
> latency=0 drop-on-latency=true ! application/x-rtp, payload=96 !
> rtph264depay ! decodebin ! glimagesink  sync=false
>
>                 data->source = gst_element_factory_make 
> ("rtspsrc","rtspsrc");
>
>                 g_object_set(G_OBJECT
> (data->source),"location",pipelineParameterFromJava,"latency",0,"drop-
> on-latency",true,NULL);
>
>  
>
>                 data->pipeline = gst_pipeline_new ("fpv-pipeline");
>
>                
> data->filter=gst_element_factory_make("capsfilter","filter");
>
>                 data->depayloader  = gst_element_factory_make 
> ("rtph264depay","rtph264depay");
>
>                 data->decoder  = gst_element_factory_make 
> ("decodebin","decodebin");
>
>                 data->distortion = gst_element_factory_make 
> ("glshader","glshader");
>
>                 data->video_sink = gst_element_factory_make 
> ("glimagesink","glimagesink");
>
>  
>
>                 filtercaps = gst_caps_new_simple 
> ("application/x-rtp","payload", G_TYPE_INT, 96,NULL);
>
>                 g_object_set (G_OBJECT (data->filter), "caps", 
> filtercaps, NULL);
>
>                 g_object_set (G_OBJECT (data->distortion), "location", 
> "/data/data/com.lonestar.groundpi/files/distortion.frag", NULL);
>
>                 gst_caps_unref (filtercaps);
>
>                 g_object_set(G_OBJECT
> (data->video_sink),"sync",false,NULL);
>
>  
>
>                 if (!data->pipeline || !data->source || !data->filter
> || !data->depayloader || !data->decoder || !data->video_sink ||
> !data->distortion) {
>
>                   g_printerr ("One element could not be created.
> Exiting.\n");
>
>                   return -1;
>
>                 }
>
>  
>
>                 gst_bin_add_many (GST_BIN (data->pipeline),
> data->source, data->filter, data->depayloader, data->decoder, 
> data->video_sink, data->distortion, NULL);
>
>                 gst_element_link_many (data->filter,
> data->depayloader, data->decoder, NULL);
>
>                 gst_element_link_many (data->distortion,
> data->video_sink, NULL);
>
>                 g_signal_connect (data->source, "pad-added", 
> G_CALLBACK (cb_new_pad), data->filter);
>
>                 g_signal_connect (data->decoder, "pad-added", 
> G_CALLBACK (cb_new_pad), data->distortion);
>
> ….
>
>  
>
>  
>
>  
>
>  
>
> Distortion.frag:
>
>  
>
> #extension GL_ARB_texture_rectangle : enable
>
> precision _mediump_ float;
>
> varying vec2 v_texcoord;
>
> uniform sampler2D _tex_;
>
> _const_vec4 _kappa_ = vec4(2.75,1.7,0.5,0.5);
>
> _const_float screen_width = 1920.0;
>
> _const_float screen_height = 1080.0;
>
> _const_float scaleFactor = 0.62;
>
> _const_vec2 leftCenter = vec2(0.25, 0.4);
>
> _const_vec2 rightCenter = vec2(0.75, 0.4);
>
> _const_float separation = -0.025;
>
> _const__bool_ stereo_input = false;
>
>  
>
> // Scales input texture coordinates for distortion.
>
> vec2 hmdWarp(vec2 LensCenter, vec2 texCoord, vec2 Scale, vec2 ScaleIn) 
> {
>
> vec2 _theta_ = (texCoord - LensCenter) * ScaleIn;
>
> float rSq = theta.x * theta.x + theta.y * theta.y;
>
> vec2 _rvector_ = _theta_ * (kappa.x + kappa.y * rSq + kappa.z * rSq * 
> rSq + kappa.w * rSq * rSq * rSq);
>
> vec2 _tc_ = LensCenter + Scale * _rvector_;
>
> return _tc_;
>
> }
>
> _bool_validate(vec2 _tc_, _int_ eye) {
>
> if ( stereo_input ) {
>
> //keep within bounds of texture
>
> if ((eye == 1 && (tc.x < 0.0 || tc.x > 0.5)) ||
>
> (eye == 0 && (tc.x < 0.5 || tc.x > 1.0)) ||
>
> tc.y < 0.0 || tc.y > 1.0) {
>
> return false;
>
> }
>
> } else {
>
> if ( tc.x < 0.0 || tc.x > 1.0 ||
>
> tc.y < 0.0 || tc.y > 1.0 ) {
>
> return false;
>
> }
>
> }
>
> return true;
>
> }
>
> void main() {
>
> float as = float(screen_width / 2.0) / float(screen_height);
>
> vec2 Scale = vec2(0.25, as);
>
> vec2 ScaleIn = vec2(2.0 * scaleFactor, 1.0 / as * scaleFactor);
>
> vec2 texCoord = v_texcoord;
>
> vec2 _tc_ = vec2(0);
>
> vec4 color = vec4(0);
>
> if ( texCoord.x < 0.5 ) {
>
> texCoord.x += separation;
>
> texCoord = hmdWarp(leftCenter, texCoord, Scale, ScaleIn );
>
> if ( !stereo_input ) {
>
> texCoord.x *= 2.0;
>
> }
>
> color = texture2D(_tex_, texCoord);
>
> if ( !validate(texCoord, 0) ) {
>
> color = vec4(0);
>
> }
>
> } else {
>
> texCoord.x -= separation;
>
> texCoord = hmdWarp(rightCenter, texCoord, Scale, ScaleIn);
>
> if ( !stereo_input ) {
>
> texCoord.x = (texCoord.x - 0.5) * 2.0;
>
> }
>
> color = texture2D(_tex_, texCoord);
>
> if ( !validate(texCoord, 1) ) {
>
> color = vec4(0);
>
> }
>
> }
>
> gl_FragColor = color;
>
> }
>
>  
>
>  
>
>  
>
>  
>
>
>
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

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