Proposal: EXT_blend_func_extended (#3553)

extensions/proposals/EXT_blend_func_extended/extension.xml

@@ -0,0 +1,148 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<proposal href="proposals/EXT_blend_func_extended/">
+  <name>EXT_blend_func_extended</name>
+
+  <contact> <a href="https://www.khronos.org/webgl/public-mailing-list/">WebGL
+  working group</a> (public_webgl 'at' khronos.org) </contact>
+
+  <contributors>
+    <contributor>Members of the WebGL working group</contributor>
+  </contributors>
+
+  <number>NN</number>
+
+  <depends>
+    <api version="1.0"/>
+  </depends>
+
+  <overview>
+    <mirrors href="https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_blend_func_extended.txt"
+             name="EXT_blend_func_extended">
+      <addendum>
+        None of the new functions are supported.
+      </addendum>
+      <addendum>
+        Automatic location assignment of fragment outputs is not supported.
+      </addendum>
+      <addendum>
+        <p>
+          <code>INVALID_OPERATION</code> is generated by attempting to draw
+          when any of the new blend factors are used for an active draw buffer,
+          which has blending enabled, and the fragment shader does not
+        </p>
+        <ul>
+          <li>
+            <strong>ESSL 1.00:</strong> statically write to <code>gl_SecondaryFragColorEXT</code>
+            or to the appropriate element of the <code>gl_SecondaryFragDataEXT[]</code> array.
+          </li>
+          <li>
+            <strong>ESSL 3.00:</strong> statically bind a compatible fragment output as the
+            secondary blending source for the corresponding draw buffer.
+          </li>
+        </ul>
+      </addendum>
+    </mirrors>
+    <features>
+      <glsl extname="GL_EXT_blend_func_extended">
+        <stage type="fragment"/>
+        <constant name="gl_MaxDualSourceDrawBuffersEXT" type="int" />
+        <feature>
+          <strong>ESSL 1.00:</strong> <code>gl_SecondaryFragColorEXT</code> and
+          <code>gl_SecondaryFragDataEXT[]</code> are built-in outputs.
+        </feature>
+        <feature>
+          <strong>ESSL 3.00:</strong> An <code>index</code> layout qualifier may be
+          used to bind fragment shader outputs as secondary blend sources.
+        </feature>
+      </glsl>
+    </features>
+  </overview>
+
+  <idl xml:space="preserve">
+[Exposed=(Window,Worker), LegacyNoInterfaceObject]
+interface EXT_blend_func_extended {
+    const GLenum SRC1_COLOR_EXT                   = 0x88F9;
+    const GLenum SRC1_ALPHA_EXT                   = 0x8589;
+    const GLenum ONE_MINUS_SRC1_COLOR_EXT         = 0x88FA;
+    const GLenum ONE_MINUS_SRC1_ALPHA_EXT         = 0x88FB;
+    const GLenum MAX_DUAL_SOURCE_DRAW_BUFFERS_EXT = 0x88FC;
+};
+  </idl>
+
+  <newtok>
+    <function name="blendFunc" type="undefined">
+      <param name="src" type="GLenum"/>
+      <param name="dst" type="GLenum"/>
+      <p>
+        New enums <code>SRC1_COLOR_EXT</code>, <code>SRC1_ALPHA_EXT</code>,
+        <code>ONE_MINUS_SRC1_COLOR_EXT</code>, and <code>ONE_MINUS_SRC1_ALPHA_EXT</code> are accepted
+        as the <code>src</code> and <code>dst</code> parameters.
+      </p>
+      <p>
+        <strong>WebGL 1.0:</strong> An existing enum <code>SRC_ALPHA_SATURATE</code> is accepted
+        as the <code>dst</code> parameter.
+      </p>
+    </function>
+
+    <function name="blendFuncSeparate" type="undefined">
+      <param name="srcRGB" type="GLenum"/>
+      <param name="dstRGB" type="GLenum"/>
+      <param name="srcAlpha" type="GLenum"/>
+      <param name="dstAlpha" type="GLenum"/>
+      <p>
+        New enums <code>SRC1_COLOR_EXT</code>, <code>SRC1_ALPHA_EXT</code>,
+        <code>ONE_MINUS_SRC1_COLOR_EXT</code>, and <code>ONE_MINUS_SRC1_ALPHA_EXT</code>
+        are accepted as the <code>srcRGB</code>, <code>dstRGB</code>, <code>srcAlpha</code>,
+        and <code>dstAlpha</code> parameters.
+      </p>
+      <p>
+        <strong>WebGL 1.0:</strong> An existing enum <code>SRC_ALPHA_SATURATE</code> is accepted
+        as the <code>dstRGB</code> and <code>dstAlpha</code> parameters.
+      </p>
+    </function>
+
+    <function name="blendFunciOES" type="undefined">
+      <param name="buf" type="GLuint"/>
+      <param name="src" type="GLenum"/>
+      <param name="dst" type="GLenum"/>
+      When <a href="../../OES_draw_buffers_indexed/">OES_draw_buffers_indexed</a> is enabled,
+      new enums <code>SRC1_COLOR_EXT</code>,
+      <code>SRC1_ALPHA_EXT</code>, <code>ONE_MINUS_SRC1_COLOR_EXT</code>, and
+      <code>ONE_MINUS_SRC1_ALPHA_EXT</code> are accepted as the <code>src</code> and <code>dst</code>
+      parameters.
+    </function>
+
+    <function name="blendFuncSeparateiOES" type="undefined">
+      <param name="buf" type="GLuint"/>
+      <param name="srcRGB" type="GLenum"/>
+      <param name="dstRGB" type="GLenum"/>
+      <param name="srcAlpha" type="GLenum"/>
+      <param name="dstAlpha" type="GLenum"/>
+      When <a href="../../OES_draw_buffers_indexed/">OES_draw_buffers_indexed</a> is enabled,
+      new enums <code>SRC1_COLOR_EXT</code>,
+      <code>SRC1_ALPHA_EXT</code>, <code>ONE_MINUS_SRC1_COLOR_EXT</code>, and
+      <code>ONE_MINUS_SRC1_ALPHA_EXT</code> are accepted as the <code>srcRGB</code>,
+      <code>dstRGB</code>, <code>srcAlpha</code>, and <code>dstAlpha</code> parameters.
+    </function>
+
+    <function name="getParameter" type="any">
+      <param name="pname" type="GLenum"/>
+      <p>
+        New <code>MAX_DUAL_SOURCE_DRAW_BUFFERS_EXT</code> enum is accepted as the <code>pname</code> parameter.
+      </p>
+      <p>
+        The return type of this method depends on the parameter queried:
+      </p>
+      <table class="foo">
+        <tr><th>pname</th><th>returned type</th></tr>
+        <tr><td>MAX_DUAL_SOURCE_DRAW_BUFFERS_EXT</td><td>GLint</td></tr>
+      </table>
+    </function>
+  </newtok>
+
+  <history>
+    <revision date="2023/06/01">
+      <change>Initial Draft.</change>
+    </revision>
+  </history>
+</proposal>