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Initial submit of WEBGL_multisampled_render_to_texture proposal
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‎extensions/proposals/WEBGL_multisampled_render_to_texture/extension.xml‎

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<?xml version="1.0"?>
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<extension href="WEBGL_multisampled_render_to_texture/">
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<name>WEBGL_multisampled_render_to_texture</name>
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<contact>
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<a href="https://www.khronos.org/webgl/public-mailing-list/">WebGL working group</a> (public_webgl 'at' khronos.org)
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</contact>
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<contributors>
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<contributor>Rik Cabanier, Facebook</contributor>
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</contributors>
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<number>??</number>
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<depends>
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<api version="1.0"/>
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</depends>
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<overview>
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<mirrors href="https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_multisampled_render_to_texture2.txt" name="EXT_multisampled_render_to_texture2">
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</mirrors>
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<features>
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<feature>
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Adds support for rendering multisampled to a color renderable texture, without requiring an explicit resolve of multisample data.
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</feature>
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</features>
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</overview>
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<idl xml:space="preserve">
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[Exposed=(Window,Worker), LegacyNoInterfaceObject]
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interface WEBGL_multisampled_render_to_texture {
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const GLenum RENDERBUFFER_SAMPLES_EXT = 0x8CAB;
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const GLenum FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT = 0x8D56;
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const GLenum MAX_SAMPLES_EXT = 0x8D57;
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const GLenum FRAMEBUFFER_ATTACHMENT_TEXTURE_SAMPLES_EXT = 0x8D6C;
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undefined renderbufferStorageMultisampleEXT(
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GLenum target, GLsizei samples,
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GLenum internalformat,
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GLsizei width, GLsizei height);
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undefined framebufferTexture2DMultisampleEXT(
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GLenum target, GLenum attachment,
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GLenum textarget, WebGLTexture? texture,
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GLint level, GLsizei samples);
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};
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</idl>
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<newfun>
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<function name="renderbufferStorageMultisampleEXT" type="undefined">
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<param name="target" type="GLenum"/>
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<param name="samples" type="GLsizei"/>
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<param name="internalformat" type="GLenum"/>
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<param name="width" type="GLsizei"/>
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<param name="height" type="GLsizei"/>
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</function>
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</newfun>
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<newfun>
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<function name="framebufferTexture2DMultisampleEXT" type="undefined">
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<param name="target" type="GLenum"/>
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<param name="attachment" type="GLenum"/>
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<param name="textarget" type="GLenum"/>
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<param name="texture" type="GLuint"/>
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<param name="level" type="GLint"/>
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<param name="samples" type="GLsizei"/>
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</function>
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</newfun>
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<newtok>
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<function name="GetRenderbufferParameter" type="any">
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<param name="target" type="GLenum"/>
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<param name="pname" type="GLenum"/>
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Calling with the <code>pname</code> set to <code>RENDERBUFFER_SAMPLES_EXT</code> returns the number of samples.
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<br/>
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<!--
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If <code>renderbufferStorageMultisampleEXT</code> is called with <code>samples</code> is zero, then <code>RENDERBUFFER_SAMPLES_EXT</code> is set to zero.
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Otherwise <code>samples</code> represents a request for a desired minimum number
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of samples. Since different implementations may support different
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sample counts for multisampled rendering, the actual number of samples
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allocated for the renderbuffer image is implementation-dependent.
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However, the resulting value for <code>RENDERBUFFER_SAMPLES_EXT</code> is
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guaranteed to be greater than or equal to samples and no more than the
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next larger sample count supported by the implementation.
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<br/>
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-->
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The return type depends on the parameter queried:
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<table width="30%">
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<tr><th>pname</th><th>returned type</th></tr>
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<tr><td>RENDERBUFFER_SAMPLES_EXT</td><td>GLint</td></tr>
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</table>
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</function>
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<function name="checkFramebufferStatus" type="GLenum">
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<param name="target" type="GLenum"/>
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</function>
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<function name="getParameter" type="any">
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<param name="pname" type="GLenum"/>
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Calling with the <code>pname</code> set to <code>MAX_SAMPLES_EXT</code> returns the maximum number of samples.
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<br/>
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The return type depends on the parameter queried:
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<table width="30%">
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<tr><th>pname</th><th>returned type</th></tr>
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<tr><td>MAX_SAMPLES_EXT</td><td>GLint</td></tr>
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</table>
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</function>
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<function name="getFramebufferAttachmentParameter" type="any">
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<param name="target" type="GLenum"/>
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<param name="attachment" type="GLenum"/>
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<param name="pname" type="GLenum"/>
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Calling with the <code>pname</code> set to <code>FRAMEBUFFER_ATTACHMENT_TEXTURE_SAMPLES_EXT</code> returns the number of samples in the multisampled texture.
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<br/>
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The return type depends on the parameter queried:
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<table width="30%">
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<tr><th>pname</th><th>returned type</th></tr>
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<tr><td>MAX_SAMPLES_EXT</td><td>GLint</td></tr>
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</table>
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</function>
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</newtok>
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<errors>
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<error>
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The error <code>OUT_OF_MEMORY</code> is generated when <code>RenderbufferStorageMultisampleEXT</code> cannot create storage of the specified size.
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</error>
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<error>
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If <code>RenderbufferStorageMultisampleEXT</code> is called with a value of <code>samples</code> that is greater than <code>MAX_SAMPLES_EXT</code>, then the error <code>INVALID_VALUE</code> is generated.
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</error>
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<error>
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The error <code>INVALID_ENUM</code> is generated if<code> FramebufferTexture2DMultisampleEXT</code> is called with a target that is not <code>FRAMEBUFFER</code>, <code>DRAW_FRAMEBUFFER</code>, or <code>READ_FRAMEBUFFER</code>.
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</error>
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<error>
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The error <code>INVALID_ENUM</code> is generated if <code>FramebufferTexture2DMultisampleEXT</code> is called with an <code>attachment</code> that is not <code>COLOR_ATTACHMENT0</code>.
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</error>
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<error>
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The error <code>INVALID_ENUM</code> is generated if <code>FramebufferTexture2DMultisampleEXT</code> is called with a textarget that is not <code>TEXTURE_2D</code>, <code>TEXTURE_CUBE_MAP_POSITIVE_X</code>, <code>TEXTURE_CUBE_MAP_POSITIVE_Y</code>, <code>TEXTURE_CUBE_MAP_POSITIVE_Z</code>, <code>TEXTURE_CUBE_MAP_NEGATIVE_X</code>, <code>TEXTURE_CUBE_MAP_NEGATIVE_Y</code>, or <code>TEXTURE_CUBE_MAP_NEGATIVE_Z</code>.
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</error>
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<error>
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The error <code>INVALID_OPERATION</code> is generated if <code>FramebufferTexture2DMultisampleEXT</code> is called with samples greater than the maximum number of samples supported for target and its internalformat.
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</error>
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</errors>
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<samplecode xml:space="preserve">
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<pre>
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var gl = document.createElement('canvas').getContext('webgl2');
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var ext = gl.getExtension('WEBGL_multisampled_render_to_texture');
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var samples = gl.getParameter(ext.MAX_SAMPLES_EXT);
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var fb = gl.createFramebuffer();
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gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, fb);
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// Create color texture and storage.
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var colorTex = gl.createTexture();
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gl.bindTexture(gl.TEXTURE_2D, colorTex);
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gl.texStorage2D(gl.TEXTURE_2D, 1, gl.RGBA8, 512, 512);
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ext.framebufferTexture2DMultisampleEXT(gl.DRAW_FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, colorTex, 0, samples);
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// Create depth texture and storage.
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var depthStencilTex = gl.createTexture();
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gl.bindTexture(gl.TEXTURE_2D, depthStencilTex);
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ext.renderbufferStorageMultisampleEXT(gl.RENDER_BUFFER, samples, gl.DEPTH32F_STENCIL8, 512, 512);
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ext.framebufferTexture2DMultisampleEXT(gl.DRAW_FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.TEXTURE_2D, depthStencilTex, 0, samples);
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gl.drawElements(...); // Draw will be done with multisampling and flushed to the non-multisample texture.
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</pre>
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</samplecode>
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<history>
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<revision date="2021/10/09">
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<change>Initial revision.</change>
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</revision>
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</history>
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</extension>

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