GL: Misc GL refactoring.

* Remove GlUtil.Program String[] constructor to unify and just use the
  String constructor.
* Add getAttributeArrayLocationAndEnable() to simplify things a tiny bit.
* Increase usage of constant values.

PiperOrigin-RevId: 407570340

libraries/common/src/main/java/androidx/media3/common/util/GlUtil.java

@@ -26,7 +26,6 @@ import android.opengl.EGLDisplay;
 import android.opengl.EGLSurface;
 import android.opengl.GLES11Ext;
 import android.opengl.GLES20;
-import android.text.TextUtils;
 import androidx.annotation.DoNotInline;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
@@ -88,18 +87,6 @@ public final class GlUtil {
       this(loadAsset(context, vertexShaderFilePath), loadAsset(context, fragmentShaderFilePath));
     }
 
-    /**
-     * Compiles a GL shader program from vertex and fragment shader GLSL GLES20 code.
-     *
-     * @param vertexShaderGlsl The vertex shader program as arrays of strings. Strings are joined by
-     *     adding a new line character in between each of them.
-     * @param fragmentShaderGlsl The fragment shader program as arrays of strings. Strings are
-     *     joined by adding a new line character in between each of them.
-     */
-    public Program(String[] vertexShaderGlsl, String[] fragmentShaderGlsl) {
-      this(TextUtils.join("\n", vertexShaderGlsl), TextUtils.join("\n", fragmentShaderGlsl));
-    }
-
     /** Uses the program. */
     public void use() {
       // Link and check for errors.
@@ -120,8 +107,19 @@ public final class GlUtil {
       GLES20.glDeleteProgram(programId);
     }
 
+    /**
+     * Returns the location of an {@link Attribute}, which has been enabled as a vertex attribute
+     * array.
+     */
+    public int getAttributeArrayLocationAndEnable(String attributeName) {
+      int location = getAttributeLocation(attributeName);
+      GLES20.glEnableVertexAttribArray(location);
+      checkGlError();
+      return location;
+    }
+
     /** Returns the location of an {@link Attribute}. */
-    public int getAttribLocation(String attributeName) {
+    private int getAttributeLocation(String attributeName) {
       return GLES20.glGetAttribLocation(programId, attributeName);
     }
 
@@ -135,7 +133,7 @@ public final class GlUtil {
       int[] attributeCount = new int[1];
       GLES20.glGetProgramiv(programId, GLES20.GL_ACTIVE_ATTRIBUTES, attributeCount, 0);
       if (attributeCount[0] != 2) {
-        throw new IllegalStateException("Expected two attributes.");
+        throw new IllegalStateException("Expected two attributes but found " + attributeCount[0]);
       }
 
       Attribute[] attributes = new Attribute[attributeCount[0]];
@@ -170,7 +168,7 @@ public final class GlUtil {
       GLES20.glGetActiveAttrib(
           programId, index, length[0], ignore, 0, size, 0, type, 0, nameBytes, 0);
       String name = new String(nameBytes, 0, strlen(nameBytes));
-      int location = getAttribLocation(name);
+      int location = getAttributeLocation(name);
 
       return new Attribute(name, index, location);
     }

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/video/VideoDecoderGLSurfaceView.java

@@ -169,8 +169,7 @@ public final class VideoDecoderGLSurfaceView extends GLSurfaceView
     public void onSurfaceCreated(GL10 unused, EGLConfig config) {
       program = new GlUtil.Program(VERTEX_SHADER, FRAGMENT_SHADER);
       program.use();
-      int posLocation = program.getAttribLocation("in_pos");
+      int posLocation = program.getAttributeArrayLocationAndEnable("in_pos");
-      GLES20.glEnableVertexAttribArray(posLocation);
       GLES20.glVertexAttribPointer(
           posLocation,
           2,
@@ -178,13 +177,9 @@ public final class VideoDecoderGLSurfaceView extends GLSurfaceView
           /* normalized= */ false,
           /* stride= */ 0,
           TEXTURE_VERTICES);
-      texLocations[0] = program.getAttribLocation("in_tc_y");
+      texLocations[0] = program.getAttributeArrayLocationAndEnable("in_tc_y");
-      GLES20.glEnableVertexAttribArray(texLocations[0]);
+      texLocations[1] = program.getAttributeArrayLocationAndEnable("in_tc_u");
-      texLocations[1] = program.getAttribLocation("in_tc_u");
+      texLocations[2] = program.getAttributeArrayLocationAndEnable("in_tc_v");
-      GLES20.glEnableVertexAttribArray(texLocations[1]);
-      texLocations[2] = program.getAttribLocation("in_tc_v");
-      GLES20.glEnableVertexAttribArray(texLocations[2]);
-      GlUtil.checkGlError();
       colorMatrixLocation = program.getUniformLocation("mColorConversion");
       GlUtil.checkGlError();
       setupTextures();
@@ -257,9 +252,9 @@ public final class VideoDecoderGLSurfaceView extends GLSurfaceView
 
       int[] widths = new int[3];
       widths[0] = outputBuffer.width;
-      // TODO: Handle streams where chroma channels are not stored at half width and height
+      // TODO(b/142097774): Handle streams where chroma channels are not stored at half width and
-      // compared to luma channel. See [Internal: b/142097774].
+      // height compared to the luma channel. U and V planes are being stored at half width compared
-      // U and V planes are being stored at half width compared to Y.
+      // to Y.
       widths[1] = widths[2] = (widths[0] + 1) / 2;
       for (int i = 0; i < 3; i++) {
         // Set cropping of stride if either width or stride has changed.

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/video/spherical/ProjectionRenderer.java

@@ -46,33 +46,27 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   }
 
   // Basic vertex & fragment shaders to render a mesh with 3D position & 2D texture data.
-  private static final String[] VERTEX_SHADER_CODE =
+  private static final String VERTEX_SHADER =
-      new String[] {
+      "uniform mat4 uMvpMatrix;\n"
-        "uniform mat4 uMvpMatrix;",
+          + "uniform mat3 uTexMatrix;\n"
-        "uniform mat3 uTexMatrix;",
+          + "attribute vec4 aPosition;\n"
-        "attribute vec4 aPosition;",
+          + "attribute vec2 aTexCoords;\n"
-        "attribute vec2 aTexCoords;",
+          + "varying vec2 vTexCoords;\n"
-        "varying vec2 vTexCoords;",
+          + "// Standard transformation.\n"
-
+          + "void main() {\n"
-        // Standard transformation.
+          + "  gl_Position = uMvpMatrix * aPosition;\n"
-        "void main() {",
+          + "  vTexCoords = (uTexMatrix * vec3(aTexCoords, 1)).xy;\n"
-        "  gl_Position = uMvpMatrix * aPosition;",
+          + "}\n";
-        "  vTexCoords = (uTexMatrix * vec3(aTexCoords, 1)).xy;",
+  private static final String FRAGMENT_SHADER =
-        "}"
+      "// This is required since the texture data is GL_TEXTURE_EXTERNAL_OES.\n"
-      };
+          + "#extension GL_OES_EGL_image_external : require\n"
-  private static final String[] FRAGMENT_SHADER_CODE =
+          + "precision mediump float;\n"
-      new String[] {
+          + "// Standard texture rendering shader.\n"
-        // This is required since the texture data is GL_TEXTURE_EXTERNAL_OES.
+          + "uniform samplerExternalOES uTexture;\n"
-        "#extension GL_OES_EGL_image_external : require",
+          + "varying vec2 vTexCoords;\n"
-        "precision mediump float;",
+          + "void main() {\n"
-
+          + "  gl_FragColor = texture2D(uTexture, vTexCoords);\n"
-        // Standard texture rendering shader.
+          + "}\n";
-        "uniform samplerExternalOES uTexture;",
-        "varying vec2 vTexCoords;",
-        "void main() {",
-        "  gl_FragColor = texture2D(uTexture, vTexCoords);",
-        "}"
-      };
 
   // Texture transform matrices.
   private static final float[] TEX_MATRIX_WHOLE = {
@@ -121,11 +115,11 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
   /** Initializes of the GL components. */
   /* package */ void init() {
-    program = new GlUtil.Program(VERTEX_SHADER_CODE, FRAGMENT_SHADER_CODE);
+    program = new GlUtil.Program(VERTEX_SHADER, FRAGMENT_SHADER);
     mvpMatrixHandle = program.getUniformLocation("uMvpMatrix");
     uTexMatrixHandle = program.getUniformLocation("uTexMatrix");
-    positionHandle = program.getAttribLocation("aPosition");
+    positionHandle = program.getAttributeArrayLocationAndEnable("aPosition");
-    texCoordsHandle = program.getAttribLocation("aTexCoords");
+    texCoordsHandle = program.getAttributeArrayLocationAndEnable("aTexCoords");
     textureHandle = program.getUniformLocation("uTexture");
   }
 
@@ -148,10 +142,6 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     checkNotNull(program).use();
     checkGlError();
 
-    GLES20.glEnableVertexAttribArray(positionHandle);
-    GLES20.glEnableVertexAttribArray(texCoordsHandle);
-    checkGlError();
-
     float[] texMatrix;
     if (stereoMode == C.STEREO_MODE_TOP_BOTTOM) {
       texMatrix = rightEye ? TEX_MATRIX_BOTTOM : TEX_MATRIX_TOP;
@@ -162,6 +152,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     }
     GLES20.glUniformMatrix3fv(uTexMatrixHandle, 1, false, texMatrix, 0);
 
+    // TODO(b/205002913): Update to use GlUtil.Uniform.bind().
     GLES20.glUniformMatrix4fv(mvpMatrixHandle, 1, false, mvpMatrix, 0);
     GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
     GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);

libraries/transformer/src/main/java/androidx/media3/transformer/TransformerTranscodingVideoRenderer.java

@@ -56,6 +56,13 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
 
   private static final String TAG = "TransformerTranscodingVideoRenderer";
 
+  // Predefined shader values.
+  private static final String VERTEX_SHADER_FILE_PATH = "shaders/blit_vertex_shader.glsl";
+  private static final String FRAGMENT_SHADER_FILE_PATH =
+      "shaders/copy_external_fragment_shader.glsl";
+  private static final int EXPECTED_NUMBER_OF_ATTRIBUTES = 2;
+  private static final int EXPECTED_NUMBER_OF_UNIFORMS = 2;
+
   private final Context context;
 
   private final DecoderInputBuffer decoderInputBuffer;
@@ -231,18 +238,16 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
     decoderTextureId = GlUtil.createExternalTexture();
     GlUtil.Program copyProgram;
     try {
-      copyProgram =
+      copyProgram = new GlUtil.Program(context, VERTEX_SHADER_FILE_PATH, FRAGMENT_SHADER_FILE_PATH);
-          new GlUtil.Program(
-              context,
-              /* vertexShaderFilePath= */ "shaders/blit_vertex_shader.glsl",
-              /* fragmentShaderFilePath= */ "shaders/copy_external_fragment_shader.glsl");
     } catch (IOException e) {
       throw new IllegalStateException(e);
     }
 
     copyProgram.use();
     GlUtil.Attribute[] copyAttributes = copyProgram.getAttributes();
-    checkState(copyAttributes.length == 2, "Expected program to have two vertex attributes.");
+    checkState(
+        copyAttributes.length == EXPECTED_NUMBER_OF_ATTRIBUTES,
+        "Expected program to have " + EXPECTED_NUMBER_OF_ATTRIBUTES + " vertex attributes.");
     for (GlUtil.Attribute copyAttribute : copyAttributes) {
       if (copyAttribute.name.equals("a_position")) {
         copyAttribute.setBuffer(
@@ -268,7 +273,9 @@ import org.checkerframework.checker.nullness.qual.RequiresNonNull;
       copyAttribute.bind();
     }
     GlUtil.Uniform[] copyUniforms = copyProgram.getUniforms();
-    checkState(copyUniforms.length == 2, "Expected program to have two uniforms.");
+    checkState(
+        copyUniforms.length == EXPECTED_NUMBER_OF_UNIFORMS,
+        "Expected program to have " + EXPECTED_NUMBER_OF_UNIFORMS + " uniforms.");
     for (GlUtil.Uniform copyUniform : copyUniforms) {
       if (copyUniform.name.equals("tex_sampler")) {
         copyUniform.setSamplerTexId(decoderTextureId, 0);