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Merge "Add SurfaceTexture docs for getTransformMatrix." into honeycomb

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Jamie Gennis
2011-01-31 14:11:26 -08:00
committed by Android (Google) Code Review
parent 8df2c42413 5f8b6653e0
commit b799314e64
1 changed files with 11 additions and 0 deletions
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graphics/java/android/graphics/SurfaceTexture.java
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@@ -32,6 +32,17 @@ import android.os.Message;
* updated to contain the most recent image from the image stream. This may cause some frames of * updated to contain the most recent image from the image stream. This may cause some frames of
* the stream to be skipped. * the stream to be skipped.
* *
* <p>When sampling from the texture one should first transform the texture coordinates using the
* matrix queried via {@link #getTransformMatrix}. The transform matrix may change each time {@link
* #updateTexImage} is called, so it should be re-queried each time the texture image is updated.
* This matrix transforms traditional 2D OpenGL ES texture coordinate column vectors of the form (s,
* t, 0, 1) where s and t are on the inclusive interval [0, 1] to the proper sampling location in
* the streamed texture. This transform compensates for any properties of the image stream source
* that cause it to appear different from a traditional OpenGL ES texture. For example, sampling
* from the bottom left corner of the image can be accomplished by transforming the column vector
* (0, 0, 0, 1) using the queried matrix, while sampling from the top right corner of the image can
* be done by transforming (1, 1, 0, 1).
*
* <p>The texture object uses the GL_TEXTURE_EXTERNAL_OES texture target, which is defined by the * <p>The texture object uses the GL_TEXTURE_EXTERNAL_OES texture target, which is defined by the
* OES_EGL_image_external OpenGL ES extension. This limits how the texture may be used. * OES_EGL_image_external OpenGL ES extension. This limits how the texture may be used.
* *