GLEDGEFLAG(3G)

✨ GLEDGEFLAG(3G) ✨

okay bestie, welcome to the GLEDGEFLAG page, section 3G of the manual 💅 this one is all about telling OpenGL which edges are boundary and which are nonboundary, and honestly? it's giving "small function, big vibes" 🦋

---

🌸 NAME 🌸

glEdgeFlag, glEdgeFlagv — flag edges as either boundary or nonboundary 🎀

---

🧚 C SPECIFICATION 🧚

void glEdgeFlag( GLboolean flag )

---

🍓 PARAMETERS 🍓

• flag — this is the current edge flag value you're setting, and it's either GL_TRUE or GL_FALSE. the initial value is GL_TRUE, no cap 👑

---

🧚 C SPECIFICATION 🧚

void glEdgeFlagv( const GLboolean *flag )

---

🍓 PARAMETERS 🍓

• flag — a pointer to an array holding a single boolean element, and that element replaces the current edge flag value ✨

---

💖 DESCRIPTION 💖

so here's the tea ☕ every vertex of a polygon, separate triangle, or separate quadrilateral that you specify between a glBegin/glEnd pair gets marked as the start of either a boundary edge or a nonboundary edge. if the current edge flag is true at the moment you specify that vertex, the vertex is marked as the start of a boundary edge 🔥 otherwise, it's marked as the start of a nonboundary edge.

glEdgeFlag sets the edge flag bit to GL_TRUE if flag is GL_TRUE, and to GL_FALSE otherwise. simple as that, periodt 💅

now the important part bestie, don't skip this: the vertices of connected triangles and connected quadrilaterals are always marked as boundary, regardless of what the edge flag value is. like, the flag doesn't even get a vote there 😭

and one more thing — boundary and nonboundary edge flags on vertices are significant only if GL_POLYGON_MODE is set to GL_POINT or GL_LINE. see glPolygonMode for that whole situation 🫶

---

🎀 NOTES 🎀

the current edge flag can be updated at any time ⏰ in particular, glEdgeFlag can be called between a call to glBegin and the corresponding call to glEnd. yes, right in the middle of the pair. iconic behaviour, we love to see it ✨

---

👑 ASSOCIATED GETS 👑

• glGet with argument GL_EDGE_FLAG 🌈

---

🦋 SEE ALSO 🦋

• glBegin(3G)
• glEdgeFlagPointer(3G)
• glPolygonMode(3G)

---

and that's the whole page, bestie!! this was GLEDGEFLAG(3G) from the OpenGL manual, section 3G — same title on the way out as on the way in, because symmetry is iconic 💜 go flag some edges, you're doing amazing sweetie 🫶✨