# Android: Sampling from movie texture does not work
**URL:** https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345
**Category:** Developing Cinder
**Created:** [October 23, 2016, 8:34pm UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345 "2016-10-23T20:34:52Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@eight\_io](https://discourse.libcinder.org/u/eight_io)
#### Post date: [October 23, 2016, 8:34pm UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/1 "2016-10-23T20:34:52Z")
I am converting iOS app to Android. iOS version has a working displacement map texture rendering, in which the displacement map is a movie texture. On Android, however, sampling from a movie texture returns zeros.
Below I removed the displacement part and simply am drawing the movie texture using a primitive shader
```auto
cinder::android::video::MovieGlRef mMovie;
gl::TextureRef mDisplaceTexture;
...
//setup
mMovie = cinder::android::video::MovieGl::create( moviePath );
mMovie->play();
...
//update
mDisplaceTexture = mMovie->getTexture();
...
//draw
gl::ScopedColor col(Color::white());
gl::ScopedModelMatrix modelScope;
gl::ScopedTextureBind a (mDisplaceTexture, 0);
gl::ScopedGlslProg shaderScp1( glsl );
glsl->uniform("mDisplaceTexture", 0);
gl::drawSolidRect( Rectf(vec2(0),getWindowSize() ) );
```
The vert shader:
```auto
#version 100
uniform mat4 ciModelViewProjection;
attribute vec4 ciPosition;
attribute vec2 ciTexCoord0;
attribute vec4 ciColor;
varying vec2 Vertex;
void main( void )
{
Vertex.xy = ciTexCoord0;
gl_Position = ciModelViewProjection * ciPosition;
}
```
The fragment shader:
```auto
#version 100
//uniform sampler2D mCamTexture;
uniform sampler2D mDisplaceTexture;
varying highp vec2 Vertex;
void main( void )
{
// highp float displace = dot(texture2D(mDisplaceTexture,vec2(Vertex.x, 1.0 - Vertex.y)).rgb, vec3(0.3, 0.6, 0.1))*0.5;
//gl_FragColor = texture2D(mCamTexture, Vertex + vec2(displace));
gl_FragColor = texture2D(mDisplaceTexture, Vertex);
}
```
This draws a black screen. No GlError thrown. The camera feed, asset pictures are displayed fine with this approach.
Playing displace texture as follows works too:
```auto
gl::color(Color::white());
gl::draw( mDisplaceTexture, Rectf(vec2(0),getWindowSize() ) );
```
What shall I look into?
Thanks.
–8
---
### Author:  [@paul.houx](https://discourse.libcinder.org/u/paul.houx)
#### Post date: [October 23, 2016, 9:15pm UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/2 "2016-10-23T21:15:00Z")
Try using `sampler2DRect` instead. This is required on Windows and OS X, so perhaps also on Android. Movies often use a `GL_TEXTURE_RECTANGLE` target that uses absolute texture coordinates instead of normalized ones.
---
### Author:  [@eight\_io](https://discourse.libcinder.org/u/eight_io)
#### Post date: [October 23, 2016, 9:22pm UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/3 "2016-10-23T21:22:31Z")
Thanks Paul.
sampler2DRect breaks the shader with
```auto
10-23 17:18:29.667 12346-12391/ru.scriptum.augmentedtheatre A/cinder: |fatal | void cinder::app::AppBase::executeLaunch()[193] Uncaught exception, type: cinder::gl::GlslProgCompileExc, what: FRAGMENT: Fragment shader compilation failed.
ERROR: 0:3: 'sampler2DRect' : Reserved word.
ERROR: 0:3: 'sampler2DRect' : Syntax error: syntax error
ERROR: 2 compilation errors. No code generated.
1: #version 100
2: uniform sampler2DRect mCamTexture;
3: uniform sampler2DRect mDisplaceTexture;
4: varying highp vec2 Vertex;
5: void main( void )
6: {
7: highp float displace = dot(texture2DRect(mDisplaceTexture,Vertex.yx).rgb, vec3(0.3, 0.6, 0.1))*0.5;
8: gl_FragColor = texture2DRect(mCamTexture, Vertex + vec2(displace));
9: }
10:
```
–8
---
### Author:  [@gabor\_papp](https://discourse.libcinder.org/u/gabor_papp)
#### Post date: [October 23, 2016, 10:04pm UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/4 "2016-10-23T22:04:31Z")
I have no experience with this, but here it shows that the texture target is `GL_TEXTURE_EXTERNAL_OES`, so I would try `uniform samplerExternalOES mCamTexture` instead.
[https://github.com/cinder/Cinder/blob/android\_linux/src/cinder/android/video/VideoPlayer.cpp#L70](https://github.com/cinder/Cinder/blob/android_linux/src/cinder/android/video/VideoPlayer.cpp#L70)
---
### Author:  [@paul.houx](https://discourse.libcinder.org/u/paul.houx)
#### Post date: [October 23, 2016, 10:45pm UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/5 "2016-10-23T22:45:43Z")
If that is the case, you may have to enable the [extension](https://www.khronos.org/registry/gles/extensions/OES/OES_EGL_image_external.txt):
`#extension GL_OES_EGL_image_external`
---
### Author:  [@eight\_io](https://discourse.libcinder.org/u/eight_io)
#### Post date: [October 24, 2016, 12:05am UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/6 "2016-10-24T00:05:27Z")
@gabor_papp and @paul.houx : Thanks, guys, but still no luck:
```auto
10-23 19:45:28.895 28622-28982/ru.scriptum.augmentedtheatre W/Adreno-ES20: : GL_INVALID_ENUM
10-23 19:45:28.895 28622-28982/ru.scriptum.augmentedtheatre A/libc: Fatal signal 6 (SIGABRT), code -6 in tid 28982 (Thread-2390)
```
Shader:
```auto
#version 100
#extension GL_OES_EGL_image_external : enable
//uniform sampler2D mCamTexture;
uniform samplerExternalOES mDisplaceTexture;
varying highp vec2 Vertex;
void main( void )
{
highp float displace = dot(texture2D(mDisplaceTexture,vec2(Vertex.x, 1.0 - Vertex.y)).rgb, vec3(0.3, 0.6, 0.1))*0.5;
//gl_FragColor = texture2D(mCamTexture, Vertex + vec2(displace));
gl_FragColor = texture2D(mDisplaceTexture, Vertex);
}
```
–8
---
### Author:  [@paul.houx](https://discourse.libcinder.org/u/paul.houx)
#### Post date: [October 24, 2016, 1:25am UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/7 "2016-10-24T01:25:49Z")
Are you rendering to an `Fbo` that has this texture bound as a target?
---
### Author:  [@eight\_io](https://discourse.libcinder.org/u/eight_io)
#### Post date: [October 24, 2016, 1:38am UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/8 "2016-10-24T01:38:50Z")
No:
> [@eight\_io](#):
>
> mDisplaceTexture = mMovie-\>getTexture();
> …
> //draw
> gl::ScopedColor col(Color::white());
> gl::ScopedModelMatrix modelScope;
> gl::ScopedTextureBind a (mDisplaceTexture, 0);
>
> ```
> gl::ScopedGlslProg shaderScp1( glsl );
> glsl->uniform("mDisplaceTexture", 0);
> gl::drawSolidRect( Rectf(vec2(0),getWindowSize() ) );
>
> ```
Also, just checked the GL\_OES\_EGL\_image\_external extension is available.
–8
---
### Author:  [@eight\_io](https://discourse.libcinder.org/u/eight_io)
#### Post date: [October 24, 2016, 4:35am UTC](https://discourse.libcinder.org/t/android-sampling-from-movie-texture-does-not-work/345/9 "2016-10-24T04:35:36Z")
@paul.houx, @gabor_papp Actually, I am taking it back. While banging on this problem, I was trying to convert a texture into a surface into a texture, and that is what was causing this SIGABRT. I removed that craziness, and now everything works.
So, GL\_OES\_EGL\_image\_external all the way to the bank.
Thanks a lot.
–8