Call getNearestSamples() in Framebuffer::setAttachment()

The app jp.garud.ssimulator uses the same sample count of '2' for both
glRenderbufferStorageMultisampleEXT() and
glFramebufferTexture2DMultisampleEXT(). However, when
glRenderbufferStorageMultisampleEXT() is called,
Renderbuffer::setStorageMultisample() calls
TextureCaps::getNearestSamples() which rounds up the sample count from
'2' to '4'.   Later, when the app tries to draw with the framebuffer,
an error is generated by ANGLE:

Framebuffer is incomplete: Attachments have different sample counts.

The fix is to also call TextureCaps::getNearestSamples() in
Framebuffer::setAttachment() to make sure the sample count passed
into glFramebufferTexture2DMultisampleEXT() is also rounded up to
match the renderbuffer.

Bug: angleproject:6183
Test: MultisampledRenderToTextureTest.FramebufferCompletenessSmallSampleCount
Change-Id: I58be9986077257f4767f2e528c2f87e496d9d774
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3036254
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>

src/libANGLE/Framebuffer.cpp

@@ -1793,8 +1793,19 @@ void Framebuffer::setAttachment(const Context *context,
                                 GLsizei numViews,
                                 GLuint baseViewIndex,
                                 bool isMultiview,
-                                GLsizei samples)
+                                GLsizei samplesIn)
 {
+    GLsizei samples = samplesIn;
+    // Match the sample count to the attachment's sample count.
+    if (resource)
+    {
+        const InternalFormat *info = resource->getAttachmentFormat(binding, textureIndex).info;
+        ASSERT(info);
+        GLenum internalformat         = info->internalFormat;
+        const TextureCaps &formatCaps = context->getTextureCaps().get(internalformat);
+        samples                       = formatCaps.getNearestSamples(samples);
+    }
+
     // Context may be null in unit tests.
     if (!context || !context->isWebGL1())
     {

src/libANGLE/Framebuffer.h

@@ -450,7 +450,7 @@ class Framebuffer final : public angle::ObserverInterface,
                        GLsizei numViews,
                        GLuint baseViewIndex,
                        bool isMultiview,
-                       GLsizei samples);
+                       GLsizei samplesIn);
     void commitWebGL1DepthStencilIfConsistent(const Context *context,
                                               GLsizei numViews,
                                               GLuint baseViewIndex,

src/libANGLE/Renderbuffer.cpp

@@ -133,7 +133,7 @@ angle::Result Renderbuffer::setStorage(const Context *context,
 }
 
 angle::Result Renderbuffer::setStorageMultisample(const Context *context,
-                                                  GLsizei samples,
+                                                  GLsizei samplesIn,
                                                   GLenum internalformat,
                                                   GLsizei width,
                                                   GLsizei height,
@@ -141,9 +141,9 @@ angle::Result Renderbuffer::setStorageMultisample(const Context *context,
 {
     ANGLE_TRY(orphanImages(context));
 
-    // Potentially adjust "samples" to a supported value
+    // Potentially adjust "samplesIn" to a supported value
     const TextureCaps &formatCaps = context->getTextureCaps().get(internalformat);
-    samples                       = formatCaps.getNearestSamples(samples);
+    GLsizei samples               = formatCaps.getNearestSamples(samplesIn);
 
     ANGLE_TRY(mImplementation->setStorageMultisample(context, samples, internalformat, width,
                                                      height, mode));

src/libANGLE/Renderbuffer.h

@@ -83,7 +83,7 @@ class Renderbuffer final : public RefCountObject<RenderbufferID>,
                              GLsizei width,
                              GLsizei height);
     angle::Result setStorageMultisample(const Context *context,
-                                        GLsizei samples,
+                                        GLsizei samplesIn,
                                         GLenum internalformat,
                                         GLsizei width,
                                         GLsizei height,

src/libANGLE/Texture.cpp

@@ -1590,7 +1590,7 @@ angle::Result Texture::setImageExternal(Context *context,
 
 angle::Result Texture::setStorageMultisample(Context *context,
                                              TextureType type,
-                                             GLsizei samples,
+                                             GLsizei samplesIn,
                                              GLint internalFormat,
                                              const Extents &size,
                                              bool fixedSampleLocations)
@@ -1603,7 +1603,7 @@ angle::Result Texture::setStorageMultisample(Context *context,
 
     // Potentially adjust "samples" to a supported value
     const TextureCaps &formatCaps = context->getTextureCaps().get(internalFormat);
-    samples                       = formatCaps.getNearestSamples(samples);
+    GLsizei samples               = formatCaps.getNearestSamples(samplesIn);
 
     mState.mImmutableFormat = true;
     mState.mImmutableLevels = static_cast<GLuint>(1);

src/libANGLE/Texture.h

@@ -465,7 +465,7 @@ class Texture final : public RefCountObject<TextureID>,
 
     angle::Result setStorageMultisample(Context *context,
                                         TextureType type,
-                                        GLsizei samples,
+                                        GLsizei samplesIn,
                                         GLint internalformat,
                                         const Extents &size,
                                         bool fixedSampleLocations);

src/tests/gl_tests/MultisampledRenderToTextureTest.cpp

@@ -484,6 +484,49 @@ TEST_P(MultisampledRenderToTextureTest, FramebufferCompleteness)
     }
 }
 
+// Checking for framebuffer completeness using extension methods.
+TEST_P(MultisampledRenderToTextureTest, FramebufferCompletenessSmallSampleCount)
+{
+    ANGLE_SKIP_TEST_IF(!EnsureGLExtensionEnabled("GL_EXT_multisampled_render_to_texture"));
+
+    // Test failure introduced by Apple's changes (anglebug.com/5505)
+    ANGLE_SKIP_TEST_IF(IsMetal() && IsAMD());
+
+    // A sample count of '2' can be rounded up to '4' on some systems (e.g., ARM+Android).
+    GLsizei samples = 2;
+
+    // Checking that Renderbuffer and texture2d having different number of samples results
+    // in a FRAMEBUFFER_INCOMPLETE_MULTISAMPLE
+    GLTexture texture;
+    glBindTexture(GL_TEXTURE_2D, texture);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 64, 64, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    ASSERT_GL_NO_ERROR();
+
+    // Texture attachment for color attachment 0.  Framebuffer should be complete.
+    GLFramebuffer FBO;
+    glBindFramebuffer(GL_FRAMEBUFFER, FBO);
+    glFramebufferTexture2DMultisampleEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
+                                         texture, 0, samples);
+    EXPECT_GL_FRAMEBUFFER_COMPLETE(GL_FRAMEBUFFER);
+
+    // Depth/stencil renderbuffer, potentially with a different sample count.
+    GLRenderbuffer dsRenderbuffer;
+    glBindRenderbuffer(GL_RENDERBUFFER, dsRenderbuffer);
+    glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER, samples, GL_DEPTH_COMPONENT16, 64, 64);
+    ASSERT_GL_NO_ERROR();
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, dsRenderbuffer);
+    EXPECT_GL_FRAMEBUFFER_COMPLETE(GL_FRAMEBUFFER);
+
+    // Color renderbuffer for color attachment 0.
+    GLRenderbuffer colorRenderbuffer;
+    glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
+    glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER, samples, GL_RGBA4, 64, 64);
+    ASSERT_GL_NO_ERROR();
+    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,
+                              colorRenderbuffer);
+    EXPECT_GL_FRAMEBUFFER_COMPLETE(GL_FRAMEBUFFER);
+}
+
 void MultisampledRenderToTextureTest::createAndAttachColorAttachment(
     bool useRenderbuffer,
     GLsizei size,