Support GL_ETC1_RGB8_OES in the OpenGL renderer.

src/libANGLE/Caps.cpp

@@ -166,6 +166,7 @@ std::vector<std::string> Extensions::getStrings() const
     InsertExtensionString("GL_EXT_texture_compression_dxt1",     textureCompressionDXT1,    &extensionStrings);
     InsertExtensionString("GL_ANGLE_texture_compression_dxt3",   textureCompressionDXT3,    &extensionStrings);
     InsertExtensionString("GL_ANGLE_texture_compression_dxt5",   textureCompressionDXT5,    &extensionStrings);
+    InsertExtensionString("GL_OES_compressed_ETC1_RGB8_texture", compressedETC1RGB8Texture, &extensionStrings);
     InsertExtensionString("GL_EXT_sRGB",                         sRGB,                      &extensionStrings);
     InsertExtensionString("GL_ANGLE_depth_texture",              depthTextures,             &extensionStrings);
     InsertExtensionString("GL_EXT_texture_storage",              textureStorage,            &extensionStrings);
@@ -184,7 +185,7 @@ std::vector<std::string> Extensions::getStrings() const
     InsertExtensionString("GL_OES_standard_derivatives",         standardDerivatives,       &extensionStrings);
     InsertExtensionString("GL_EXT_shader_texture_lod",           shaderTextureLOD,          &extensionStrings);
     InsertExtensionString("GL_NV_shader_framebuffer_fetch",      NVshaderFramebufferFetch,  &extensionStrings);
-    InsertExtensionString("GL_ARM_shader_framebuffer_fetch",   ARMshaderFramebufferFetch,&extensionStrings);
+    InsertExtensionString("GL_ARM_shader_framebuffer_fetch",     ARMshaderFramebufferFetch, &extensionStrings);
     InsertExtensionString("GL_EXT_shader_framebuffer_fetch",     shaderFramebufferFetch,    &extensionStrings);
     InsertExtensionString("GL_EXT_frag_depth",                   fragDepth,                 &extensionStrings);
     InsertExtensionString("GL_ANGLE_texture_usage",              textureUsage,              &extensionStrings);
@@ -353,6 +354,15 @@ static bool DetermineDXT5TextureSupport(const TextureCapsMap &textureCaps)
     return GetFormatSupport(textureCaps, requiredFormats, true, true, false);
 }
 
+// Check for GL_ETC1_RGB8_OES
+static bool DetermineETC1RGB8TextureSupport(const TextureCapsMap &textureCaps)
+{
+    std::vector<GLenum> requiredFormats;
+    requiredFormats.push_back(GL_ETC1_RGB8_OES);
+
+    return GetFormatSupport(textureCaps, requiredFormats, true, true, false);
+}
+
 // Check for GL_ANGLE_texture_compression_dxt5
 static bool DetermineSRGBTextureSupport(const TextureCapsMap &textureCaps)
 {
@@ -406,6 +416,7 @@ void Extensions::setTextureExtensionSupport(const TextureCapsMap &textureCaps)
     textureCompressionDXT1 = DetermineDXT1TextureSupport(textureCaps);
     textureCompressionDXT3 = DetermineDXT3TextureSupport(textureCaps);
     textureCompressionDXT5 = DetermineDXT5TextureSupport(textureCaps);
+    compressedETC1RGB8Texture = DetermineETC1RGB8TextureSupport(textureCaps);
     sRGB = DetermineSRGBTextureSupport(textureCaps);
     depthTextures = DetermineDepthTextureSupport(textureCaps);
     colorBufferFloat = DetermineColorBufferFloatSupport(textureCaps);

src/libANGLE/Caps.h

@@ -80,6 +80,7 @@ struct Extensions
     // GL_OES_texture_float, GL_OES_texture_float_linear
     // GL_EXT_texture_rg
     // GL_EXT_texture_compression_dxt1, GL_ANGLE_texture_compression_dxt3, GL_ANGLE_texture_compression_dxt5
+    // GL_OES_compressed_ETC1_RGB8_texture
     // GL_EXT_sRGB
     // GL_ANGLE_depth_texture
     // GL_EXT_color_buffer_float
@@ -138,6 +139,10 @@ struct Extensions
     bool textureCompressionDXT3;
     bool textureCompressionDXT5;
 
+    // GL_OES_compressed_ETC1_RGB8_texture
+    // Implies that TextureCaps for GL_ETC1_RGB8_OES exist
+    bool compressedETC1RGB8Texture;
+
     // GL_EXT_sRGB
     // Implies that TextureCaps for GL_SRGB8_ALPHA8 and GL_SRGB8 exist
     // TODO: Don't advertise this extension in ES3

src/libANGLE/formatutils.cpp

@@ -469,6 +469,9 @@ static InternalFormatInfoMap BuildInternalFormatInfoMap()
     // From GL_ANGLE_texture_compression_dxt5
     map.insert(InternalFormatInfoPair(GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE, CompressedFormat(4, 4, 128, 4, GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE, GL_UNSIGNED_BYTE, false, RequireExt<&Extensions::textureCompressionDXT5>,    NeverSupported, AlwaysSupported)));
 
+    // From GL_OES_compressed_ETC1_RGB8_texture
+    map.insert(InternalFormatInfoPair(GL_ETC1_RGB8_OES,                   CompressedFormat(4, 4,  64, 3, GL_ETC1_RGB8_OES,                   GL_UNSIGNED_BYTE, false, RequireExt<&Extensions::compressedETC1RGB8Texture>, NeverSupported, AlwaysSupported)));
+
     // For STENCIL_INDEX8 we chose a normalized component type for the following reasons:
     // - Multisampled buffer are disallowed for non-normalized integer component types and we want to support it for STENCIL_INDEX8
     // - All other stencil formats (all depth-stencil) are either float or normalized

src/libANGLE/renderer/gl/formatutilsgl.cpp

@@ -246,6 +246,10 @@ static InternalFormatInfoMap BuildInternalFormatInfoMap()
 
     // From GL_ANGLE_texture_compression_dxt5
     InsertFormatMapping(&map, GL_COMPRESSED_RGBA_S3TC_DXT5_ANGLE, ExtsOnly("GL_EXT_texture_compression_s3tc"),     Always(), Never(), ExtsOnly("GL_ANGLE_texture_compression_dxt5"), Always(), Never());
+
+    // From GL_ETC1_RGB8_OES
+    InsertFormatMapping(&map, GL_ETC1_RGB8_OES,                   VersionOrExts(4, 3, "GL_ARB_ES3_compatibility"), Always(), Never(), VersionOrExts(3, 0, "GL_ETC1_RGB8_OES"), Always(), Never());
+
     // clang-format on
 
     return map;
@@ -382,6 +386,35 @@ static GLenum GetNativeFormat(const FunctionsGL *functions,
     return result;
 }
 
+static GLenum GetNativeCompressedFormat(const FunctionsGL *functions,
+                                        const WorkaroundsGL &workarounds,
+                                        GLenum format)
+{
+    GLenum result = format;
+
+    if (functions->standard == STANDARD_GL_DESKTOP)
+    {
+        if (format == GL_ETC1_RGB8_OES)
+        {
+            // GL_ETC1_RGB8_OES is not available in any desktop GL extension but the compression
+            // format is forwards compatible so just use the ETC2 format.
+            result = GL_COMPRESSED_RGB8_ETC2;
+        }
+    }
+
+    if (functions->isAtLeastGLES(gl::Version(3, 0)))
+    {
+        if (format == GL_ETC1_RGB8_OES)
+        {
+            // Pass GL_COMPRESSED_RGB8_ETC2 as the target format in ES3 and higher because it
+            // becomes a core format.
+            result = GL_COMPRESSED_RGB8_ETC2;
+        }
+    }
+
+    return result;
+}
+
 static GLenum GetNativeType(const FunctionsGL *functions,
                             const WorkaroundsGL &workarounds,
                             GLenum type)
@@ -439,7 +472,7 @@ CompressedTexImageFormat GetCompressedTexImageFormat(const FunctionsGL *function
                                                      GLenum internalFormat)
 {
     CompressedTexImageFormat result;
-    result.internalFormat = internalFormat;
+    result.internalFormat = GetNativeCompressedFormat(functions, workarounds, internalFormat);
     return result;
 }
 
@@ -448,7 +481,7 @@ CompressedTexSubImageFormat GetCompressedSubTexImageFormat(const FunctionsGL *fu
                                                            GLenum format)
 {
     CompressedTexSubImageFormat result;
-    result.format = format;
+    result.format = GetNativeCompressedFormat(functions, workarounds, format);
     return result;
 }