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Diffstat (limited to 'third_party/rust/khronos_api/api_webgl/extensions/WEBGL_draw_buffers/extension.xml')
| -rw-r--r-- | third_party/rust/khronos_api/api_webgl/extensions/WEBGL_draw_buffers/extension.xml | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/third_party/rust/khronos_api/api_webgl/extensions/WEBGL_draw_buffers/extension.xml b/third_party/rust/khronos_api/api_webgl/extensions/WEBGL_draw_buffers/extension.xml new file mode 100644 index 0000000000..106ebce4fb --- /dev/null +++ b/third_party/rust/khronos_api/api_webgl/extensions/WEBGL_draw_buffers/extension.xml @@ -0,0 +1,185 @@ +<?xml version="1.0"?> + +<ratified href="WEBGL_draw_buffers/"> + <name>WEBGL_draw_buffers</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>18</number> + <depends> + <api version="1.0"/> + <core version="2.0"> + <glsl version="300 es"/> + </core> + </depends> + <overview> + <mirrors href="https://www.khronos.org/registry/gles/extensions/EXT/EXT_draw_buffers.txt" name="EXT_draw_buffers"> + <addendum> + The implementation must support a minimum of 4 color attachments. + </addendum> + <addendum> + The value of the <code>MAX_COLOR_ATTACHMENTS_WEBGL</code> parameter must be greater than or + equal to that of the <code>MAX_DRAW_BUFFERS_WEBGL</code> parameter. + </addendum> + <addendum> + If: + <ul> + <li> A framebuffer's color attachments are all textures allocated with format <code>RGBA</code> + and type <code>UNSIGNED_BYTE</code>, and </li> + <li> The framebuffer has either: + <ul> + <li> No depth or stencil attachment </li> + <li> A valid <code>DEPTH</code> or <code>DEPTH_STENCIL</code> attachment </li> + </ul></li> + </ul> + Then a call to <code>checkFramebufferStatus</code> against this framebuffer must not return + <code>FRAMEBUFFER_UNSUPPORTED</code>. (In other words, the implementation must support the + use of <code>RGBA/UNSIGNED_BYTE</code> textures as color attachments, plus either a + <code>DEPTH</code> or <code>DEPTH_STENCIL</code> attachment.) + </addendum> + <addendum> + Attaching <code>n</code> consecutive color attachments starting at COLOR_ATTACHMENT0_WEBGL, + where <code>n</code> is between 1 and <code>MAX_DRAW_BUFFERS_WEBGL</code>, must not return + <code>FRAMEBUFFER_UNSUPPORTED</code> from a call to <code>checkFramebufferStatus</code>. In + other words, if <code>MAX_DRAW_BUFFERS_WEBGL</code> is 4, then the implementation is + required to support the following combinations of color attachments: + + <ul> + <li> <code>COLOR_ATTACHMENT0_WEBGL = RGBA/UNSIGNED_BYTE</code></li> + <li> <code>COLOR_ATTACHMENT0_WEBGL = RGBA/UNSIGNED_BYTE</code><br/> + <code>COLOR_ATTACHMENT1_WEBGL = RGBA/UNSIGNED_BYTE</code><br/></li> + <li> <code>COLOR_ATTACHMENT0_WEBGL = RGBA/UNSIGNED_BYTE</code><br/> + <code>COLOR_ATTACHMENT1_WEBGL = RGBA/UNSIGNED_BYTE</code><br/> + <code>COLOR_ATTACHMENT2_WEBGL = RGBA/UNSIGNED_BYTE</code><br/></li> + <li> <code>COLOR_ATTACHMENT0_WEBGL = RGBA/UNSIGNED_BYTE</code><br/> + <code>COLOR_ATTACHMENT1_WEBGL = RGBA/UNSIGNED_BYTE</code><br/> + <code>COLOR_ATTACHMENT2_WEBGL = RGBA/UNSIGNED_BYTE</code><br/> + <code>COLOR_ATTACHMENT3_WEBGL = RGBA/UNSIGNED_BYTE</code><br/></li> + </ul> + </addendum> + <addendum> + Although the extension name is prefixed with WEBGL the extension must be enabled with the + <code>#extension GL_EXT_draw_buffers</code> directive, as shown in the sample code, to use + the extension in a shader. + + Likewise the shading language preprocessor <code>#define GL_EXT_draw_buffers</code>, will be defined to 1 if the extension is supported. + </addendum> + <addendum> + The value of <code>gl_MaxDrawBuffers</code> must match <code>MAX_DRAW_BUFFERS_WEBGL</code> from the API if the extension is enabled in a WebGL context; otherwise, the value must be 1. Whether or not the extension is enabled with the <code>#extension GL_EXT_draw_buffers</code> directive in a shader does not affect the value of <code>gl_MaxDrawBuffers</code>. The value of <code>gl_MaxDrawBuffers</code> is a constant in the shader, and is guaranteed to be frozen at program link time. It is implementation-dependent whether it is frozen at shader compile time. (A consequence is that if a program is linked, and later the WEBGL_draw_buffers extension is enabled, the value of <code>gl_MaxDrawBuffers</code> seen by that program will still be 1.) + </addendum> + <addendum> + If the WEBGL_draw_buffers extension is enabled, but the fragment shader does not contain the <code>#extension GL_EXT_draw_buffers</code> directive to enable it, then writes to <code>gl_FragColor</code> are only written to <code>COLOR_ATTACHMENT0_WEBGL</code>, and not broadcast to all color attachments. In this scenario, other color attachments are guaranteed to remain untouched. + </addendum> + <addendum> + If a fragment shader writes to neither <code>gl_FragColor</code> nor <code>gl_FragData</code>, the values of + the fragment colors following shader execution are untouched. + + If a fragment shader contains the <code>#extension GL_EXT_draw_buffers</code> directive, all + <code>gl_FragData</code> variables (from <code>gl_FragData[0]</code> to <code>gl_FragData[MAX_DRAW_BUFFERS_WEBGL - 1]</code>) + default to zero if no values are written to them during a shader execution. + </addendum> + <addendum> + If an image is attached to more than one color attachment point in a framebuffer, <code>checkFramebufferStatus</code> + returns <code>FRAMEBUFFER_UNSUPPORTED</code>. An image can be an individual mip level, or a face of cube map. + </addendum> + </mirrors> + <features> + <feature> + Adds support for multiple color buffers and color outputs from fragment shaders. + </feature> + </features> + </overview> + <idl xml:space="preserve"> +[NoInterfaceObject] +interface WEBGL_draw_buffers { + const GLenum COLOR_ATTACHMENT0_WEBGL = 0x8CE0; + const GLenum COLOR_ATTACHMENT1_WEBGL = 0x8CE1; + const GLenum COLOR_ATTACHMENT2_WEBGL = 0x8CE2; + const GLenum COLOR_ATTACHMENT3_WEBGL = 0x8CE3; + const GLenum COLOR_ATTACHMENT4_WEBGL = 0x8CE4; + const GLenum COLOR_ATTACHMENT5_WEBGL = 0x8CE5; + const GLenum COLOR_ATTACHMENT6_WEBGL = 0x8CE6; + const GLenum COLOR_ATTACHMENT7_WEBGL = 0x8CE7; + const GLenum COLOR_ATTACHMENT8_WEBGL = 0x8CE8; + const GLenum COLOR_ATTACHMENT9_WEBGL = 0x8CE9; + const GLenum COLOR_ATTACHMENT10_WEBGL = 0x8CEA; + const GLenum COLOR_ATTACHMENT11_WEBGL = 0x8CEB; + const GLenum COLOR_ATTACHMENT12_WEBGL = 0x8CEC; + const GLenum COLOR_ATTACHMENT13_WEBGL = 0x8CED; + const GLenum COLOR_ATTACHMENT14_WEBGL = 0x8CEE; + const GLenum COLOR_ATTACHMENT15_WEBGL = 0x8CEF; + + const GLenum DRAW_BUFFER0_WEBGL = 0x8825; + const GLenum DRAW_BUFFER1_WEBGL = 0x8826; + const GLenum DRAW_BUFFER2_WEBGL = 0x8827; + const GLenum DRAW_BUFFER3_WEBGL = 0x8828; + const GLenum DRAW_BUFFER4_WEBGL = 0x8829; + const GLenum DRAW_BUFFER5_WEBGL = 0x882A; + const GLenum DRAW_BUFFER6_WEBGL = 0x882B; + const GLenum DRAW_BUFFER7_WEBGL = 0x882C; + const GLenum DRAW_BUFFER8_WEBGL = 0x882D; + const GLenum DRAW_BUFFER9_WEBGL = 0x882E; + const GLenum DRAW_BUFFER10_WEBGL = 0x882F; + const GLenum DRAW_BUFFER11_WEBGL = 0x8830; + const GLenum DRAW_BUFFER12_WEBGL = 0x8831; + const GLenum DRAW_BUFFER13_WEBGL = 0x8832; + const GLenum DRAW_BUFFER14_WEBGL = 0x8833; + const GLenum DRAW_BUFFER15_WEBGL = 0x8834; + + const GLenum MAX_COLOR_ATTACHMENTS_WEBGL = 0x8CDF; + const GLenum MAX_DRAW_BUFFERS_WEBGL = 0x8824; + + void drawBuffersWEBGL(sequence<GLenum> buffers); +}; + </idl> + <samplecode xml:space="preserve"> + <pre> + #extension GL_EXT_draw_buffers : require + precision mediump float; + void main() { + gl_FragData[0] = vec4(1.0, 0.0, 0.0, 1.0); + gl_FragData[1] = vec4(0.0, 1.0, 0.0, 1.0); + gl_FragData[2] = vec4(0.0, 0.0, 1.0, 1.0); + gl_FragData[3] = vec4(1.0, 1.0, 1.0, 1.0); + } + </pre> + </samplecode> + <history> + <revision date="2012/10/16"> + <change>Initial revision.</change> + </revision> + <revision date="2012/11/05"> + <change>Corrected typo in drawBuffersWEBGL. Changed referenced spec version to 1.0 to fix broken link.</change> + </revision> + <revision date="2013/02/02"> + <change>Renamed to EXT_draw_buffers per plan of OpenGL ES working group. Moved to draft status. Assigned number.</change> + </revision> + <revision date="2013/03/05"> + <change>Renamed to WEBGL_draw_buffers per discussion on public_webgl list. Added guarantees to make it easier for developers to use the extension.</change> + </revision> + <revision date="2013/06/07"> + <change>Clarified naming of shader directives.</change> + </revision> + <revision date="2014/07/15"> + <change>Added NoInterfaceObject extended attribute.</change> + </revision> + <revision date="2014/08/08"> + <change>Ratified by Khronos Board of Promoters.</change> + </revision> + <revision date="2016/06/28"> + <change>Revised behavior of gl_MaxDrawBuffers and gl_FragColor broadcasting, to avoid significant performance impact for WebGL 1.0 implementations running on top of the desktop OpenGL API.</change> + </revision> + <revision date="2016/07/08"> + <change>Removed undefined behaviors.</change> + </revision> + <revision date="2016/07/11"> + <change>Revised user-defined variable behavior to default to zero.</change> + </revision> + <revision date="2016/07/23"> + <change>Revised behavior of the same image is attached to more than one color attachment point.</change> + </revision> + </history> +</ratified> |