Protocol for texture sequences, like animations, movies, etc.

Ensure to respect the texture coordinates provided by TextureFrame.getTexture().getImageTexCoords().

The user's shader shall be fitted for this implementation. Assuming we use a base shader code w/o headers using ShaderCode. (Code copied from unit test / demo TexCubeES2)

   static final String[] es2_prelude = { "#version 100\n", "precision mediump float;\n" };
   static final String gl2_prelude = "#version 110\n";
   static final String shaderBasename = "texsequence_xxx";  // the base shader code w/o headers
   static final String myTextureLookupName = "myTexture2D"; // the desired texture lookup function

   private void initShader(GL2ES2 gl, TextureSequence texSeq) {
       // Create & Compile the shader objects
       ShaderCode rsVp = ShaderCode.create(gl, GL2ES2.GL_VERTEX_SHADER, TexCubeES2.class,
                                           "shader", "shader/bin", shaderBasename, true);
       ShaderCode rsFp = ShaderCode.create(gl, GL2ES2.GL_FRAGMENT_SHADER, TexCubeES2.class,
                                           "shader", "shader/bin", shaderBasename, true);

       // Prelude shader code w/ GLSL profile specifics [ 1. pre-proc, 2. other ]
       int rsFpPos;
       if(gl.isGLES2()) {
           // insert ES2 version string in beginning
           rsVp.insertShaderSource(0, 0, es2_prelude[0]);
           rsFpPos = rsFp.insertShaderSource(0, 0, es2_prelude[0]);
       } else {
           // insert GL2 version string in beginning
           rsVp.insertShaderSource(0, 0, gl2_prelude);
           rsFpPos = rsFp.insertShaderSource(0, 0, gl2_prelude);
       }
       // insert required extensions as determined by TextureSequence implementation.
       rsFpPos = rsFp.insertShaderSource(0, rsFpPos, texSeq.getRequiredExtensionsShaderStub());
       if(gl.isGLES2()) {
           // insert ES2 default precision declaration
           rsFpPos = rsFp.insertShaderSource(0, rsFpPos, es2_prelude[1]);
       }
       // negotiate the texture lookup function name
       final String texLookupFuncName = texSeq.getTextureLookupFunctionName(myTextureLookupName);

       // in case a fixed lookup function is being chosen, replace the name in our code
       rsFp.replaceInShaderSource(myTextureLookupName, texLookupFuncName);

       // Cache the TextureSequence shader details in StringBuilder:
       final StringBuilder sFpIns = new StringBuilder();

       // .. declaration of the texture sampler using the implementation specific type
       sFpIns.append("uniform ").append(texSeq.getTextureSampler2DType()).append(" mgl_ActiveTexture;\n");

       // .. the actual texture lookup function, maybe null in case a built-in function is being used
       sFpIns.append(texSeq.getTextureLookupFragmentShaderImpl());

       // Now insert the TextureShader details in our shader after the given tag:
       rsFp.insertShaderSource(0, "TEXTURE-SEQUENCE-CODE-BEGIN", 0, sFpIns);

       // Create & Link the shader program
       ShaderProgram sp = new ShaderProgram();
       sp.add(rsVp);
       sp.add(rsFp);
       if(!sp.link(gl, System.err)) {
           throw new GLException("Couldn't link program: "+sp);
       }
       ...

The above procedure might look complicated, however, it allows most flexibility and workarounds to also deal with GLSL bugs.

#extension GL_OES_EGL_image_external : enable

  vec4 funcName(in getTextureSampler2DType() image, in vec2 texCoord) {
     vec4 texColor = do_something_with(image, texCoord);
     return texColor;
  }

#extension GL_OES_EGL_image_external : enable

  vec4 funcName(in getTextureSampler2DType() image, in vec2 texCoord) {
     vec4 texColor = do_something_with(image, texCoord);
     return texColor;
  }