Change Validation For Indexed Draw Without ELEMENT_ARRAY_BUFFER

extensions/ANGLE_client_arrays.txt

@@ -70,9 +70,9 @@ Additions to the OpenGL ES Specification
 
     Add to the end of section 2.9.2 "Array Indices in Buffer Objects":
 
-    Rendering commands that draw more than 0 primitives using index data when
-    no buffer is bound to the ELEMENT_ARRAY_BUFFER binding point when
-    CLIENT_ARRAYS_ANGLE is TRUE generate an INVALID_OPERATION error.
+    Rendering commands that draw using index data when no buffer is bound to
+    the ELEMENT_ARRAY_BUFFER binding point when CLIENT_ARRAYS_ANGLE is TRUE
+    generate an INVALID_OPERATION error.
 
 New State
 
@@ -95,6 +95,9 @@ Issues
 
 Revision History
 
-    Rev.    Date         Author     Changes
-    ----  -------------  ---------  ----------------------------------------
-      1   Feb 13, 2016   geofflang  Initial version
+    Rev.    Date         Author                 Changes
+    ----  -------------  ---------              ----------------------------------------
+      2   Jun 12, 2018   Brandon Jones (Intel)  Remove primitives > 0 requirement to error
+                                                when doing an indexed draw with no bound
+                                                ELEMENT_ARRAY_BUFFER
+      1   Feb 13, 2016   geofflang              Initial version

src/libANGLE/validationES.cpp

@@ -3055,11 +3055,11 @@ bool ValidateDrawElementsCommon(Context *context,
     if (context->getExtensions().webglCompatibility ||
         !context->getGLState().areClientArraysEnabled())
     {
-        if (!elementArrayBuffer && count > 0)
+        if (!elementArrayBuffer)
         {
             // [WebGL 1.0] Section 6.2 No Client Side Arrays
-            // If drawElements is called with a count greater than zero, and no WebGLBuffer is bound
-            // to the ELEMENT_ARRAY_BUFFER binding point, an INVALID_OPERATION error is generated.
+            // If an indexed draw command (drawElements) is called and no WebGLBuffer is bound to
+            // the ELEMENT_ARRAY_BUFFER binding point, an INVALID_OPERATION error is generated.
             ANGLE_VALIDATION_ERR(context, InvalidOperation(), MustHaveElementArrayBinding);
             return false;
         }

src/tests/gl_tests/WebGLCompatibilityTest.cpp

@@ -1470,6 +1470,26 @@ TEST_P(WebGLCompatibilityTest, DrawArraysBufferOutOfBoundsNonInstanced)
     EXPECT_GL_ERROR(GL_INVALID_OPERATION);
 }
 
+// Test for drawing with a null index buffer
+TEST_P(WebGLCompatibilityTest, NullIndexBuffer)
+{
+    const std::string &vert =
+        "attribute float a_pos;\n"
+        "void main()\n"
+        "{\n"
+        "    gl_Position = vec4(a_pos, a_pos, a_pos, 1.0);\n"
+        "}\n";
+
+    ANGLE_GL_PROGRAM(program, vert, essl1_shaders::fs::Red());
+    glUseProgram(program.get());
+
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
+    glEnableVertexAttribArray(0);
+
+    glDrawElements(GL_TRIANGLES, 0, GL_UNSIGNED_BYTE, 0);
+    EXPECT_GL_ERROR(GL_INVALID_OPERATION);
+}
+
 // Test the checks for OOB reads in the vertex buffers, instanced version
 TEST_P(WebGL2CompatibilityTest, DrawArraysBufferOutOfBoundsInstanced)
 {