Nuke three remaining uages of PRIM_QUAD in drawobject.c

This was slightly less obvious, especially particle billboard drawing.
That one now requires 1.5 times more space in VBOs and ParticleDrawData
buffers, since we have to draw two triangles per particle, instead of a
single quad... And diagonal of each quad is now drawn in wire mode, not
sure how much we consider this an issue (as in, will this particle draw
code change a lot in future?).

From quick check on the web seems there is no other way to do anyway. :/

source/blender/editors/space_view3d/drawobject.c

@@ -1894,29 +1894,20 @@ static void drawcamera_volume(float near_plane[4][3], float far_plane[4][3], boo
 	drawcamera_frame(far_plane, filled, pos);
 
 	if (filled) {
-#ifdef WITH_GL_PROFILE_COMPAT
+		immBegin(PRIM_TRIANGLE_STRIP, 10);
-		immBegin(PRIM_QUADS_XXX, 16); /* TODO(merwin): use PRIM_TRIANGLE_STRIP here */
+
 		immVertex3fv(pos, near_plane[0]);
 		immVertex3fv(pos, far_plane[0]);
-		immVertex3fv(pos, far_plane[1]);
-		immVertex3fv(pos, near_plane[1]);
-
 		immVertex3fv(pos, near_plane[1]);
 		immVertex3fv(pos, far_plane[1]);
-		immVertex3fv(pos, far_plane[2]);
-		immVertex3fv(pos, near_plane[2]);
-
 		immVertex3fv(pos, near_plane[2]);
 		immVertex3fv(pos, far_plane[2]);
-		immVertex3fv(pos, far_plane[3]);
-		immVertex3fv(pos, near_plane[3]);
-
 		immVertex3fv(pos, near_plane[3]);
 		immVertex3fv(pos, far_plane[3]);
-		immVertex3fv(pos, far_plane[0]);
 		immVertex3fv(pos, near_plane[0]);
+		immVertex3fv(pos, far_plane[0]);
+
 		immEnd();
-#endif
 	}
 	else {
 		immBegin(PRIM_LINES, 8);
@@ -5635,9 +5626,7 @@ static void draw_particle_arrays_new(int draw_as, int ob_dt, int select,
 			else
 				glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
 
-#ifdef WITH_GL_PROFILE_COMPAT
+			draw_vertex_array(PRIM_TRIANGLES, vert, nor, color, 0, 6 * totpoint, col);
-			draw_vertex_array(PRIM_QUADS_XXX, vert, nor, color, 0, 4 * totpoint, col);
-#endif
 			break;
 		default:
 			draw_vertex_array(PRIM_POINTS, vert, nor, color, 0, totpoint, col);
@@ -5762,18 +5751,13 @@ static void draw_particle(ParticleKey *state, int draw_as, short draw, float pix
 		case PART_DRAW_BB:
 		{
 			float xvec[3], yvec[3], zvec[3], bb_center[3];
-			if (cd) {
-				cd[0] = cd[3] = cd[6] = cd[9] = ma_col[0];
-				cd[1] = cd[4] = cd[7] = cd[10] = ma_col[1];
-				cd[2] = cd[5] = cd[8] = cd[11] = ma_col[2];
-				pdd->cd += 12;
-			}
 
 			copy_v3_v3(bb->vec, state->co);
 			copy_v3_v3(bb->vel, state->vel);
 
 			psys_make_billboard(bb, xvec, yvec, zvec, bb_center);
-			
+
+			/* First tri */
 			add_v3_v3v3(pdd->vd, bb_center, xvec);
 			add_v3_v3(pdd->vd, yvec); pdd->vd += 3;
 
@@ -5783,13 +5767,24 @@ static void draw_particle(ParticleKey *state, int draw_as, short draw, float pix
 			sub_v3_v3v3(pdd->vd, bb_center, xvec);
 			sub_v3_v3v3(pdd->vd, pdd->vd, yvec); pdd->vd += 3;
 
+			/* Second tri */
+			add_v3_v3v3(pdd->vd, bb_center, xvec);
+			add_v3_v3(pdd->vd, yvec); pdd->vd += 3;
+
+			sub_v3_v3v3(pdd->vd, bb_center, xvec);
+			sub_v3_v3v3(pdd->vd, pdd->vd, yvec); pdd->vd += 3;
+
 			add_v3_v3v3(pdd->vd, bb_center, xvec);
 			sub_v3_v3v3(pdd->vd, pdd->vd, yvec); pdd->vd += 3;
 
-			copy_v3_v3(pdd->nd, zvec); pdd->nd += 3;
+			if (cd) {
-			copy_v3_v3(pdd->nd, zvec); pdd->nd += 3;
+				for (int i = 0; i < 6; i++, cd += 3, pdd->cd += 3) {
-			copy_v3_v3(pdd->nd, zvec); pdd->nd += 3;
+					copy_v3_v3(cd, ma_col);
-			copy_v3_v3(pdd->nd, zvec); pdd->nd += 3;
+				}
+			}
+			for (int i = 0; i < 6; i++, pdd->nd += 3) {
+				copy_v3_v3(pdd->nd, zvec);
+			}
 			break;
 		}
 	}
@@ -6053,7 +6048,7 @@ static void draw_new_particle_system(Scene *scene, View3D *v3d, RegionView3D *rv
 				tot_vec_size *= 2;
 				break;
 			case PART_DRAW_BB:
-				tot_vec_size *= 4;
+				tot_vec_size *= 6;  /* New OGL only understands tris, no choice here. */
 				create_ndata = 1;
 				break;
 		}
@@ -7986,30 +7981,25 @@ static void draw_forcefield(Object *ob, RegionView3D *rv3d,
 
 static void imm_draw_box(const float vec[8][3], bool solid, unsigned pos)
 {
-	static const GLubyte quad_indices[24] = {0,1,2,3,7,6,5,4,4,5,1,0,3,2,6,7,3,7,4,0,1,5,6,2};
-	static const GLubyte line_indices[24] = {0,1,1,2,2,3,3,0,0,4,4,5,5,6,6,7,7,4,1,5,2,6,3,7};
-
-	const GLubyte *indices;
-	GLenum prim_type;
-
 	if (solid) {
-		indices = quad_indices;
+		/* Adpated from "Optimizing Triangle Strips for Fast Rendering" by F. Evans, S. Skiena and A. Varshney
-#ifdef WITH_GL_PROFILE_COMPAT
+		 *              (http://www.cs.umd.edu/gvil/papers/av_ts.pdf). */
-		prim_type = PRIM_QUADS_XXX;
+		static const GLubyte tris_strip_indices[14] = {0,1,3,2,6,1,5,0,4,3,7,6,4,5};
-#else
+		immBegin(PRIM_TRIANGLE_STRIP, 14);
-		return;
+		for (int i = 0; i < 14; ++i) {
-#endif
+			immVertex3fv(pos, vec[tris_strip_indices[i]]);
+		}
+		immEnd();
 	}
 	else {
-		indices = line_indices;
+		static const GLubyte line_indices[24] = {0,1,1,2,2,3,3,0,0,4,4,5,5,6,6,7,7,4,1,5,2,6,3,7};
-		prim_type = PRIM_LINES;
+		immBegin(PRIM_LINES, 24);
+		for (int i = 0; i < 24; ++i) {
+			immVertex3fv(pos, vec[line_indices[i]]);
+		}
+		immEnd();
 	}
 
-	immBegin(prim_type, 24);
-	for (int i = 0; i < 24; ++i) {
-		immVertex3fv(pos, vec[indices[i]]);
-	}
-	immEnd();
 }
 
 static void imm_draw_bb(BoundBox *bb, char type, bool around_origin, const unsigned char ob_wire_col[4])