GLDRAWELEMENTS(3G)

💅 NAME 💅

okay so this is the GLDRAWELEMENTS(3G) page, bestie — it's literally the manual for glDrawElements, aka render primitives from array data. iconic behavior only 💖

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✨ C SPECIFICATION ✨

void glDrawElements( GLenum mode,
                     GLsizei count,
                     GLenum type,
                     const GLvoid *indices )

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🎀 PARAMETERS 🎀

• mode — tells the function what kind of primitives to render. the accepted symbolic constants are GL_POINTS, GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES, GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, GL_TRIANGLES, GL_QUAD_STRIP, GL_QUADS, and GL_POLYGON. yes all of those, no cap ✨
• count — the number of elements to be rendered. that's the count, bestie 🔢
• type — the type of the values in indices. it must be one of GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT, or GL_UNSIGNED_INT. no improvising 💅
• indices — a pointer to the location where the indices are stored. it's giving "here's where the index data lives" 🫶

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🦋 DESCRIPTION 🦋

glDrawElements specifies multiple geometric primitives with very few subroutine calls. instead of calling a GL function to pass each individual vertex, normal, texture coordinate, edge flag, or color, you can prespecify separate arrays of vertices, normals, and so on, and then use them to construct a sequence of primitives with a single call to glDrawElements. literally efficiency slay 🔥

when glDrawElements is called, it uses count sequential elements from an enabled array, starting at indices, to construct a sequence of geometric primitives. mode specifies what kind of primitives are constructed, and how the array elements construct these primitives. if more than one array is enabled, each is used. if GL_VERTEX_ARRAY is not enabled, no geometric primitives are constructed. periodt.

vertex attributes that are modified by glDrawElements have an unspecified value after glDrawElements returns. for example, if GL_COLOR_ARRAY is enabled, the value of the current color is undefined after glDrawElements executes. attributes that aren't modified maintain their previous values. so yeah, don't go assuming the modified ones are cute and predictable 😭

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🌸 NOTES 🌸

• glDrawElements is available only if the GL version is 1.1 or greater. version check, bestie ⭐
• glDrawElements is included in display lists. if glDrawElements is entered into a display list, the necessary array data — determined by the array pointers and enables — is also entered into the display list. because the array pointers and enables are client-side state, their values affect display lists when the lists are created, not when the lists are executed. that's the whole vibe: creation time, not execution time 💅

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💀 ERRORS 💀

• GL_INVALID_ENUM is generated if mode is not an accepted value. wrong mode = rude 🙈
• GL_INVALID_VALUE is generated if count is negative. negative count is a no ❌
• GL_INVALID_OPERATION is generated if glDrawElements is executed between the execution of glBegin and the corresponding glEnd. do not do that, bestie 💀

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🔥 SEE ALSO 🔥

• glArrayElement(3G)
• glColorPointer(3G)
• glDrawArrays(3G)
• glDrawRangeElements(3G)
• glEdgeFlagPointer(3G)
• glGetPointerv(3G)
• glIndexPointer(3G)
• glInterleavedArrays(3G)
• glNormalPointer(3G)
• glTexCoordPointer(3G)
• glVertexPointer(3G)

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okay bye bestie 🫶 the footer is literally just GLDRAWELEMENTS(3G) again — no extra source/version/date line hiding down there, so that's the whole cute sign-off: GLDRAWELEMENTS(3G) 💖✨🎀