WebGL: Validate the read and write buffers for BlitFramebuffer are unique.

src/libANGLE/validationES.cpp

@@ -2648,6 +2648,15 @@ bool ValidateBlitFramebufferParameters(ValidationContext *context,
                         context->handleError(Error(GL_INVALID_OPERATION));
                         return false;
                     }
+
+                    if (context->getExtensions().webglCompatibility &&
+                        *readColorBuffer == *attachment)
+                    {
+                        context->handleError(
+                            Error(GL_INVALID_OPERATION,
+                                  "Read and write color attachments cannot be the same image."));
+                        return false;
+                    }
                 }
             }
 
@@ -2696,6 +2705,14 @@ bool ValidateBlitFramebufferParameters(ValidationContext *context,
                     context->handleError(Error(GL_INVALID_OPERATION));
                     return false;
                 }
+
+                if (context->getExtensions().webglCompatibility && *readBuffer == *drawBuffer)
+                {
+                    context->handleError(Error(
+                        GL_INVALID_OPERATION,
+                        "Read and write depth stencil attachments cannot be the same image."));
+                    return false;
+                }
             }
             // WebGL 2.0 BlitFramebuffer when blitting from a missing attachment
             else if (drawBuffer)

src/tests/gl_tests/WebGLCompatibilityTest.cpp

@@ -1550,6 +1550,73 @@ TEST_P(WebGL2CompatibilityTest, ClearBufferTypeCompatibity)
     EXPECT_GL_NO_ERROR();
 }
 
+// Verify that errors are generate when trying to blit from an image to itself
+TEST_P(WebGL2CompatibilityTest, BlitFramebufferSameImage)
+{
+    GLTexture textures[2];
+    glBindTexture(GL_TEXTURE_2D, textures[0]);
+    glTexStorage2D(GL_TEXTURE_2D, 3, GL_RGBA8, 4, 4);
+    glBindTexture(GL_TEXTURE_2D, textures[1]);
+    glTexStorage2D(GL_TEXTURE_2D, 3, GL_RGBA8, 4, 4);
+
+    GLRenderbuffer renderbuffers[2];
+    glBindRenderbuffer(GL_RENDERBUFFER, renderbuffers[0]);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 4, 4);
+    glBindRenderbuffer(GL_RENDERBUFFER, renderbuffers[1]);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 4, 4);
+
+    GLFramebuffer framebuffers[2];
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffers[0]);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, framebuffers[1]);
+
+    ASSERT_GL_NO_ERROR();
+
+    // Same texture
+    glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textures[0],
+                           0);
+    glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textures[0],
+                           0);
+    ASSERT_GL_NO_ERROR();
+    glBlitFramebuffer(0, 0, 4, 4, 0, 0, 4, 4, GL_COLOR_BUFFER_BIT, GL_NEAREST);
+    ASSERT_GL_ERROR(GL_INVALID_OPERATION);
+
+    // Same textures but different renderbuffers
+    glFramebufferRenderbuffer(GL_READ_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
+                              renderbuffers[0]);
+    glFramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
+                              renderbuffers[1]);
+    ASSERT_GL_NO_ERROR();
+    glBlitFramebuffer(0, 0, 4, 4, 0, 0, 4, 4, GL_DEPTH_BUFFER_BIT, GL_NEAREST);
+    ASSERT_GL_NO_ERROR();
+    glBlitFramebuffer(0, 0, 4, 4, 0, 0, 4, 4, GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT,
+                      GL_NEAREST);
+    ASSERT_GL_NO_ERROR();
+    glBlitFramebuffer(0, 0, 4, 4, 0, 0, 4, 4,
+                      GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT,
+                      GL_NEAREST);
+    ASSERT_GL_ERROR(GL_INVALID_OPERATION);
+
+    // Same renderbuffers but different textures
+    glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textures[0],
+                           0);
+    glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textures[1],
+                           0);
+    glFramebufferRenderbuffer(GL_READ_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
+                              renderbuffers[0]);
+    glFramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
+                              renderbuffers[0]);
+    ASSERT_GL_NO_ERROR();
+    glBlitFramebuffer(0, 0, 4, 4, 0, 0, 4, 4, GL_COLOR_BUFFER_BIT, GL_NEAREST);
+    ASSERT_GL_NO_ERROR();
+    glBlitFramebuffer(0, 0, 4, 4, 0, 0, 4, 4, GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT,
+                      GL_NEAREST);
+    ASSERT_GL_ERROR(GL_INVALID_OPERATION);
+    glBlitFramebuffer(0, 0, 4, 4, 0, 0, 4, 4,
+                      GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT,
+                      GL_NEAREST);
+    ASSERT_GL_ERROR(GL_INVALID_OPERATION);
+}
+
 // Use this to select which configurations (e.g. which renderer, which GLES major version) these
 // tests should be run against.
 ANGLE_INSTANTIATE_TEST(WebGLCompatibilityTest,