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ImDrawList: wip reimplement thick line strip rendering. (merged commits from PR 2964, rebased, minor styling tweaks)

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Pavel Potoček 2020-11-26 17:43:43 +01:00 committed by ocornut
parent 8199457a7d
commit 6fb700bc6f
1 changed files with 258 additions and 1 deletions
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259
imgui_draw.cpp
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@ -716,7 +716,7 @@ void ImDrawList::PrimQuadUV(const ImVec2& a, const ImVec2& b, const ImVec2& c, c
#define IM_FIXNORMAL2F_MAX_INVLEN2 100.0f // 500.0f (see #4053, #3366)
#define IM_FIXNORMAL2F(VX,VY) { float d2 = VX*VX + VY*VY; if (d2 > 0.000001f) { float inv_len2 = 1.0f / d2; if (inv_len2 > IM_FIXNORMAL2F_MAX_INVLEN2) inv_len2 = IM_FIXNORMAL2F_MAX_INVLEN2; VX *= inv_len2; VY *= inv_len2; } } (void)0
// TODO: Thickness anti-aliased lines cap are missing their AA fringe.
// FIXME: Thickness anti-aliased lines cap are missing their AA fringe.
// We avoid using the ImVec2 math operators here to reduce cost to a minimum for debug/non-inlined builds.
void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32 col, ImDrawFlags flags, float thickness)
{
@ -728,6 +728,262 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
const int count = closed ? points_count : points_count - 1; // The number of line segments we need to draw
const bool thick_line = (thickness > _FringeScale);
// (Intentionally incorrect indentation to avoid altering)
bool USE_NEW_CODE = true;
//bool USE_NEW_CODE = ImGui::GetIO().KeyShift;
if (USE_NEW_CODE)
{
const float AA_SIZE = 1.0f;
const ImU32 col_trans = col & ~IM_COL32_A_MASK;
const bool antialias = (Flags & ImDrawListFlags_AntiAliasedLines) != 0;
if (antialias && !thick_line)
{
// Anti-aliased stroke approximation
const int idx_count = count * 12;
const int vtx_count = count * 6; // FIXME-OPT: Not sharing edges
PrimReserve(idx_count, vtx_count);
ImU32 col_faded = col;
if (thickness < 1.0f)
col_faded = col_trans | ((int)(((col >> IM_COL32_A_SHIFT) & 0xFF) * thickness) << IM_COL32_A_SHIFT);
for (int i1 = 0; i1 < count; i1++)
{
const int i2 = (i1 + 1) == points_count ? 0 : i1 + 1;
const ImVec2& p1 = points[i1];
const ImVec2& p2 = points[i2];
float dx = p2.x - p1.x;
float dy = p2.y - p1.y;
IM_NORMALIZE2F_OVER_ZERO(dx, dy);
dx *= AA_SIZE;
dy *= AA_SIZE;
_VtxWritePtr[0].pos.x = p1.x + dy; _VtxWritePtr[0].pos.y = p1.y - dx; _VtxWritePtr[0].uv = opaque_uv; _VtxWritePtr[0].col = col_trans;
_VtxWritePtr[1].pos.x = p1.x; _VtxWritePtr[1].pos.y = p1.y; _VtxWritePtr[1].uv = opaque_uv; _VtxWritePtr[1].col = col_faded;
_VtxWritePtr[2].pos.x = p1.x - dy; _VtxWritePtr[2].pos.y = p1.y + dx; _VtxWritePtr[2].uv = opaque_uv; _VtxWritePtr[2].col = col_trans;
_VtxWritePtr[3].pos.x = p2.x + dy; _VtxWritePtr[3].pos.y = p2.y - dx; _VtxWritePtr[3].uv = opaque_uv; _VtxWritePtr[3].col = col_trans;
_VtxWritePtr[4].pos.x = p2.x; _VtxWritePtr[4].pos.y = p2.y; _VtxWritePtr[4].uv = opaque_uv; _VtxWritePtr[4].col = col_faded;
_VtxWritePtr[5].pos.x = p2.x - dy; _VtxWritePtr[5].pos.y = p2.y + dx; _VtxWritePtr[5].uv = opaque_uv; _VtxWritePtr[5].col = col_trans;
_VtxWritePtr += 6;
_IdxWritePtr[0] = (ImDrawIdx)(_VtxCurrentIdx); _IdxWritePtr[1] = (ImDrawIdx)(_VtxCurrentIdx + 1); _IdxWritePtr[2] = (ImDrawIdx)(_VtxCurrentIdx + 4);
_IdxWritePtr[3] = (ImDrawIdx)(_VtxCurrentIdx); _IdxWritePtr[4] = (ImDrawIdx)(_VtxCurrentIdx + 4); _IdxWritePtr[5] = (ImDrawIdx)(_VtxCurrentIdx + 3);
_IdxWritePtr[6] = (ImDrawIdx)(_VtxCurrentIdx + 1); _IdxWritePtr[7] = (ImDrawIdx)(_VtxCurrentIdx + 2); _IdxWritePtr[8] = (ImDrawIdx)(_VtxCurrentIdx + 5);
_IdxWritePtr[9] = (ImDrawIdx)(_VtxCurrentIdx + 1); _IdxWritePtr[10]= (ImDrawIdx)(_VtxCurrentIdx + 5); _IdxWritePtr[11]= (ImDrawIdx)(_VtxCurrentIdx + 4);
_IdxWritePtr += 12;
_VtxCurrentIdx += 6;
}
}
else
{
// Precise line with bevels on acute angles
const int max_n_vtx = antialias ? 6 : 3;
const int max_n_idx = 3 * (antialias ? 9 : 3);
const int vtx_count = points_count * max_n_vtx;
const int idx_count = count * max_n_idx;
PrimReserve(idx_count, vtx_count);
const float half_thickness = (antialias ? thickness - AA_SIZE : thickness) * 0.5f;
const float half_thickness_aa = half_thickness + AA_SIZE;
const unsigned int first_vtx_idx = _VtxCurrentIdx;
float sqlen1 = 0.0f;
float dx1, dy1;
if (closed)
{
dx1 = points[0].x - points[points_count - 1].x;
dy1 = points[0].y - points[points_count - 1].y;
sqlen1 = dx1 * dx1 + dy1 * dy1;
IM_NORMALIZE2F_OVER_ZERO(dx1, dy1);
}
for (int i1 = 0; i1 < points_count; i1++)
{
const int i2 = (i1 + 1 == points_count) ? 0 : i1 + 1;
const ImVec2& p1 = points[i1];
const ImVec2& p2 = points[i2];
float dx2 = p1.x - p2.x;
float dy2 = p1.y - p2.y;
float sqlen2 = dx2 * dx2 + dy2 * dy2;
IM_NORMALIZE2F_OVER_ZERO(dx2, dy2);
if (!closed && i1 == 0)
{
dx1 = -dx2;
dy1 = -dy2;
sqlen1 = sqlen2;
}
else if (!closed && i1 == points_count - 1)
{
dx2 = -dx1;
dy2 = -dy1;
sqlen2 = sqlen1;
}
float miter_l_recip = dx1 * dy2 - dy1 * dx2;
float mlx, mly, mrx, mry; // Left and right miters
float mlax, mlay, mrax, mray; // Left and right miters including anti-aliasing
const bool bevel = (dx1 * dx2 + dy1 * dy2) > 1e-5f;
if (ImFabs(miter_l_recip) > 1e-5f)
{
float miter_l = half_thickness / miter_l_recip;
// Limit (inner) miter so it doesn't shoot away when miter is longer than adjacent line segments on acute angles
if (bevel)
{
// This is too aggressive (not exactly precise)
float min_sqlen = sqlen1 > sqlen2 ? sqlen2 : sqlen1;
float miter_sqlen = ((dx1 + dx2) * (dx1 + dx2) + (dy1 + dy2) * (dy1 + dy2)) * miter_l * miter_l;
if (miter_sqlen > min_sqlen)
miter_l *= ImSqrt(min_sqlen / miter_sqlen);
}
mlx = p1.x - (dx1 + dx2) * miter_l;
mly = p1.y - (dy1 + dy2) * miter_l;
mrx = p1.x + (dx1 + dx2) * miter_l;
mry = p1.y + (dy1 + dy2) * miter_l;
if (antialias)
{
float miter_al = half_thickness_aa / miter_l_recip;
mlax = p1.x - (dx1 + dx2) * miter_al;
mlay = p1.y - (dy1 + dy2) * miter_al;
mrax = p1.x + (dx1 + dx2) * miter_al;
mray = p1.y + (dy1 + dy2) * miter_al;
}
}
else
{
// Avoid degeneracy for (nearly) straight lines
mlx = p1.x + dy1 * half_thickness;
mly = p1.y - dx1 * half_thickness;
mrx = p1.x - dy1 * half_thickness;
mry = p1.y + dx1 * half_thickness;
if (antialias)
{
mlax = p1.x + dy1 * half_thickness_aa;
mlay = p1.y - dx1 * half_thickness_aa;
mrax = p1.x - dy1 * half_thickness_aa;
mray = p1.y + dx1 * half_thickness_aa;
}
}
// The two bevel vertices if the angle is right or obtuse
// miter_sign == 1, iff the outer (maybe bevelled) edge is on the right, -1 iff it is on the left
int miter_sign = (miter_l_recip >= 0) - (miter_l_recip < 0);
float b1x, b1y, b2x, b2y; // First and second bevel point
float b1ax, b1ay, b2ax, b2ay; // First and second bevel point including anti-aliasing
if (bevel)
{
// FIXME-OPT: benchmark if doing these computations only once in AA case saves cycles
b1x = p1.x + (dx1 - dy1 * miter_sign) * half_thickness;
b1y = p1.y + (dy1 + dx1 * miter_sign) * half_thickness;
b2x = p1.x + (dx2 + dy2 * miter_sign) * half_thickness;
b2y = p1.y + (dy2 - dx2 * miter_sign) * half_thickness;
if (antialias)
{
b1ax = p1.x + (dx1 - dy1 * miter_sign) * half_thickness_aa;
b1ay = p1.y + (dy1 + dx1 * miter_sign) * half_thickness_aa;
b2ax = p1.x + (dx2 + dy2 * miter_sign) * half_thickness_aa;
b2ay = p1.y + (dy2 - dx2 * miter_sign) * half_thickness_aa;
}
}
// Set the previous line direction so it doesn't need to be recomputed
dx1 = -dx2;
dy1 = -dy2;
sqlen1 = sqlen2;
// Now that we have all the point coordinates, put them into buffers
// Vertices for each point are ordered in vertex buffer like this (looking in the direction of the polyline):
// - left vertex*
// - right vertex*
// - left vertex AA fringe* (if antialias)
// - right vertex AA fringe* (if antialias)
// - the remaining vertex (if bevel)
// - the remaining vertex AA fringe (if bevel and antialias)
// (*) if there is bevel, these vertices are the ones on the incoming edge.
// Having all the vertices of the incoming edge in predictable positions is important - we reference them
// even if we don't know relevant line properties yet
const int vertex_count = antialias ? (bevel ? 6 : 4) : (bevel ? 3 : 2); // FIXME: shorten the expression
const unsigned int bi = antialias ? 4 : 2; // Outgoing edge bevel vertex index
const bool bevel_l = bevel && miter_sign < 0;
const bool bevel_r = bevel && miter_sign > 0;
_VtxWritePtr[0].pos.x = bevel_l ? b1x : mlx; _VtxWritePtr[0].pos.y = bevel_l ? b1y : mly; _VtxWritePtr[0].uv = opaque_uv; _VtxWritePtr[0].col = col;
_VtxWritePtr[1].pos.x = bevel_r ? b1x : mrx; _VtxWritePtr[1].pos.y = bevel_r ? b1y : mry; _VtxWritePtr[1].uv = opaque_uv; _VtxWritePtr[1].col = col;
if (bevel)
{
_VtxWritePtr[bi].pos.x = b2x; _VtxWritePtr[bi].pos.y = b2y; _VtxWritePtr[bi].uv = opaque_uv; _VtxWritePtr[bi].col = col;
}
if (antialias)
{
_VtxWritePtr[2].pos.x = bevel_l ? b1ax : mlax; _VtxWritePtr[2].pos.y = bevel_l ? b1ay : mlay; _VtxWritePtr[2].uv = opaque_uv; _VtxWritePtr[2].col = col_trans;
_VtxWritePtr[3].pos.x = bevel_r ? b1ax : mrax; _VtxWritePtr[3].pos.y = bevel_r ? b1ay : mray; _VtxWritePtr[3].uv = opaque_uv; _VtxWritePtr[3].col = col_trans;
if (bevel)
{
_VtxWritePtr[5].pos.x = b2ax; _VtxWritePtr[5].pos.y = b2ay; _VtxWritePtr[5].uv = opaque_uv; _VtxWritePtr[5].col = col_trans;
}
}
_VtxWritePtr += vertex_count;
if (i1 < count)
{
const int vtx_next_id = i1 < points_count - 1 ? _VtxCurrentIdx + vertex_count : first_vtx_idx;
unsigned int l1i = _VtxCurrentIdx + (bevel_l ? bi : 0);
unsigned int r1i = _VtxCurrentIdx + (bevel_r ? bi : 1);
unsigned int l2i = vtx_next_id;
unsigned int r2i = vtx_next_id + 1;
unsigned int ebi = _VtxCurrentIdx + (bevel_l ? 0 : 1); // incoming edge bevel vertex index
_IdxWritePtr[0] = (ImDrawIdx)l1i; _IdxWritePtr[1] = (ImDrawIdx)r1i; _IdxWritePtr[2] = (ImDrawIdx)r2i;
_IdxWritePtr[3] = (ImDrawIdx)l1i; _IdxWritePtr[4] = (ImDrawIdx)r2i; _IdxWritePtr[5] = (ImDrawIdx)l2i;
_IdxWritePtr += 6;
if (bevel)
{
_IdxWritePtr[0] = (ImDrawIdx)l1i; _IdxWritePtr[1] = (ImDrawIdx)r1i; _IdxWritePtr[2] = (ImDrawIdx)ebi;
_IdxWritePtr += 3;
}
if (antialias)
{
unsigned int l1ai = _VtxCurrentIdx + (bevel_l ? 5 : 2);
unsigned int r1ai = _VtxCurrentIdx + (bevel_r ? 5 : 3);
unsigned int l2ai = vtx_next_id + 2;
unsigned int r2ai = vtx_next_id + 3;
_IdxWritePtr[0] = (ImDrawIdx)l1ai; _IdxWritePtr[1] = (ImDrawIdx)l1i; _IdxWritePtr[2] = (ImDrawIdx)l2i;
_IdxWritePtr[3] = (ImDrawIdx)l1ai; _IdxWritePtr[4] = (ImDrawIdx)l2i; _IdxWritePtr[5] = (ImDrawIdx)l2ai;
_IdxWritePtr[6] = (ImDrawIdx)r1ai; _IdxWritePtr[7] = (ImDrawIdx)r1i; _IdxWritePtr[8] = (ImDrawIdx)r2i;
_IdxWritePtr[9] = (ImDrawIdx)r1ai; _IdxWritePtr[10] = (ImDrawIdx)r2i; _IdxWritePtr[11] = (ImDrawIdx)r2ai;
_IdxWritePtr += 12;
if (bevel)
{
_IdxWritePtr[0] = (ImDrawIdx)(_VtxCurrentIdx + (bevel_r ? 1 : 2));
_IdxWritePtr[1] = (ImDrawIdx)(_VtxCurrentIdx + (bevel_r ? 3 : 0));
_IdxWritePtr[2] = (ImDrawIdx)(_VtxCurrentIdx + (bevel_r ? 5 : 4));
_IdxWritePtr[3] = (ImDrawIdx)(_VtxCurrentIdx + (bevel_r ? 1 : 2));
_IdxWritePtr[4] = (ImDrawIdx)(_VtxCurrentIdx + (bevel_r ? 5 : 4));
_IdxWritePtr[5] = (ImDrawIdx)(_VtxCurrentIdx + (bevel_r ? 4 : 5));
_IdxWritePtr += 6;
}
}
}
_VtxCurrentIdx += vertex_count;
}
const int unused_indices = (int)(IdxBuffer.Data + IdxBuffer.Size - _IdxWritePtr);
const int unused_vertices = (int)(VtxBuffer.Size - _VtxCurrentIdx - _CmdHeader.VtxOffset);
if (unused_indices > 0 || unused_vertices > 0)
PrimUnreserve(unused_indices, unused_vertices);
}
}
else
{
if (Flags & ImDrawListFlags_AntiAliasedLines)
{
// Anti-aliased stroke
@ -973,6 +1229,7 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
}
}
}
}
// - We intentionally avoid using ImVec2 and its math operators here to reduce cost to a minimum for debug/non-inlined builds.
// - Filled shapes must always use clockwise winding order. The anti-aliasing fringe depends on it. Counter-clockwise shapes will have "inward" anti-aliasing.