gistfile1.txt

//this copies the logic of void ImDrawList::AddConvexPolyFilled()
static void imgui_fixQuadFilledVerts(ImDrawList *draw_list, int vert_offset, ImVec2 *points, mgColour opt_col) {
	MG_ASSERT(draw_list->VtxBuffer.Size > vert_offset - 8);
	const int points_count = 4;
	ImDrawVert *vert_ptr = draw_list->VtxBuffer.Data + vert_offset;
	if (draw_list->Flags & ImDrawListFlags_AntiAliasedFill) {
		// Anti-aliased Fill
        const float AA_SIZE = 1.0f;
        // Compute normals
		ImVec2 temp_normals[points_count];
        for (int i0 = points_count-1, i1 = 0; i1 < points_count; i0 = i1++)
        {
            const ImVec2& p0 = points[i0];
            const ImVec2& p1 = points[i1];
            float dx = p1.x - p0.x;
            float dy = p1.y - p0.y;
            IM_NORMALIZE2F_OVER_ZERO___(dx, dy);
            temp_normals[i0].x = dy;
            temp_normals[i0].y = -dx;
        }
		for (int i0 = points_count-1, i1 = 0; i1 < points_count; i0 = i1++)
        {
            // Average normals
            const ImVec2& n0 = temp_normals[i0];
            const ImVec2& n1 = temp_normals[i1];
            float dm_x = (n0.x + n1.x) * 0.5f;
            float dm_y = (n0.y + n1.y) * 0.5f;
            IM_FIXNORMAL2F___(dm_x, dm_y);
            dm_x *= AA_SIZE * 0.5f;
            dm_y *= AA_SIZE * 0.5f;

            // Add vertices
            vert_ptr[0].pos.x = (points[i1].x - dm_x); vert_ptr[0].pos.y = (points[i1].y - dm_y);// vert_ptr[0].uv = uv; vert_ptr[0].col = col;        // Inner
            vert_ptr[1].pos.x = (points[i1].x + dm_x); vert_ptr[1].pos.y = (points[i1].y + dm_y);// vert_ptr[1].uv = uv; vert_ptr[1].col = col_trans;  // Outer
			if (opt_col.packed) {
				vert_ptr[0].col = opt_col.packed;
			}
            vert_ptr += 2;
        }
	} else {
		// Non Anti-aliased Fill
        for (int i = 0; i < points_count; i++) {
            vert_ptr[i].pos = points[i]; //_VtxWritePtr[0].uv = uv; _VtxWritePtr[0].col = col;
			if (opt_col.packed) {
				vert_ptr[i].col = opt_col.packed;
			}
        }
	}
}