GLVIEWPORTINDEXED(3G)

📦
version 1.1 · 7 versions
, in centos-stream 9

💅 GLVIEWPORTINDEXED 💅 (3G, obviously)

okay so bestie, welcome to the GLVIEWPORTINDEXED page from the 3G manual section — this is the one about setting one specific viewport by index, and honestly it's giving "I only need to move one of my many little rectangles" energy 🎀

✨ NAME ✨

glViewportIndexed — set a specified viewport. that's it. that's the whole name. slay 💅

🎀 C SPECIFICATION 🎀

here's the exact signature tea, no cap:

void glViewportIndexedf(GLuint index, GLfloat x, GLfloat y, GLfloat w,
                        GLfloat h);

void glViewportIndexedfv(GLuint index, const GLfloat *v);

🌸 PARAMETERS 🌸

  • index — the first viewport to set. like, which one are we touching bestie 🫶
  • x, y — for glViewportIndexedf, these specify the lower left corner of the viewport rectangle, in pixels. the initial value is (0,0) ⭐
  • w, h — for glViewportIndexedf, these specify the width and height of the viewport. and here's the cute detail: when a GL context is first attached to a window, w and h are set to the dimensions of that window 🪟✨
  • v — for glViewportIndexedfv, this specifies the address of an array containing the viewport parameters. it's a pointer, she's pointing at stuff, periodt 💀

🦋 DESCRIPTION 🦋

so glViewportIndexedf and glViewportIndexedfv specify the parameters for a single viewport. index specifies the index of the viewport to modify, and index must be less than the value of GL_MAX_VIEWPORTS — that's the vibe check, don't fail it 🙈

for glViewportIndexedf, x, y, w, and h specify the left, bottom, width and height of the viewport in pixels, respectively. icon behavior.

for glViewportIndexedfv, v contains the address of an array of floating point values specifying the left (x), bottom (y), width (w), and height (h) of each viewport, in that order. x and y give the location of the viewport's lower left corner, and w and h give the width and height of the viewport, respectively 🧚

the viewport specifies the affine transformation of x and y from normalized device coordinates to window coordinates. let x nd and y nd be normalized device coordinates. then the window coordinates x w and y w are computed as follows:

x w = x nd + 1 ⁢ width 2 + x
y w = y nd + 1 ⁢ height 2 + y

the location of the viewport's bottom left corner, given by (x, y), is clamped to be within the implementation-dependent viewport bounds range. and like — you can find out what that range is! the viewport bounds range [min, max] can be determined by calling glGet() with argument GL_VIEWPORT_BOUNDS_RANGE 🌈

viewport width and height are silently clamped to a range that depends on the implementation — silently, bestie, she doesn't even tell you 😭 to query this range, call glGet() with argument GL_MAX_VIEWPORT_DIMS.

the precision with which the GL interprets the floating point viewport bounds is implementation-dependent and may be determined by querying the implementation-defined constant GL_VIEWPORT_SUBPIXEL_BITS 🔍

calling glViewportIndexedfv is equivalent to calling glViewportArray() with first set to index, count set to 1 and v passed directly. and glViewportIndexedf is equivalent to this whole little guy right here:

void glViewportIndexedf(GLuint index, GLfloat x, GLfloat y, GLfloat w, GLfloat h) {
    const float v[4]  = { x, y, w, h };
    glViewportArrayv(index, 1, v);
}

like, it's literally just wrapping the array version. main character energy for a helper function, honestly 👑

🔥 ERRORS 🔥

  • GL_INVALID_VALUE is generated if index is greater than or equal to the value of GL_MAX_VIEWPORTS 😬
  • GL_INVALID_VALUE is generated if either w or h is negative. yeah. negative width is not the move, don't do it 💀

👑 ASSOCIATED GETS 👑

  • glGet() with argument GL_VIEWPORT
  • glGet() with argument GL_MAX_VIEWPORT_DIMS
  • glGet() with argument GL_VIEWPORT_BOUNDS_RANGE
  • glGet() with argument GL_VIEWPORT_SUBPIXEL_BITS

all the glGet() calls you could ever want, fr fr 🫶

⭐ VERSION SUPPORT ⭐

so the original had a whole big grid, and I'm gonna give you the exact same info in list form because tables are not the vibe here:

  • glViewportIndexedf — 2.0: -, 2.1: -, 3.0: -, 3.1: -, 3.2: -, 3.3: -, 4.0: -, 4.1: ✔, 4.2: ✔, 4.3: ✔, 4.4: ✔, 4.5: ✔
  • glViewportIndexedfv — 2.0: -, 2.1: -, 3.0: -, 3.1: -, 3.2: -, 3.3: -, 4.0: -, 4.1: ✔, 4.2: ✔, 4.3: ✔, 4.4: ✔, 4.5: ✔

tl;dr: it shows up in 4.1 and stays winning through 4.5 ✨ everyone before 4.1? not invited 🚫

🌈 SEE ALSO 🌈

  • glDepthRange()
  • glViewport()
  • glViewportArray()

go read your other faves, iykyk 💖

Copyright © 2010-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.

💜 COPYRIGHT (yes, again — the page really does this twice) 💜

Copyright © 2010-2014 Khronos Group

ok that's the whole page, you made it to the end, I'm so proud of you 🥹💐

and for the cute sign-off: this little number came from [FIXME: source], dated 08/09/2021, and it lives under GLVIEWPORTINDEXED(3G) — go forth and set exactly one viewport, bestie 🌸🦋💅

📦 where this page comes from