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godot/scene/2d/line_builder.cpp

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/*************************************************************************/
/* line_builder.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md) */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#include "line_builder.h"
//----------------------------------------------------------------------------
// Util
//----------------------------------------------------------------------------
enum SegmentIntersectionResult {
SEGMENT_PARALLEL = 0,
SEGMENT_NO_INTERSECT = 1,
SEGMENT_INTERSECT = 2
};
static SegmentIntersectionResult segment_intersection(
Vector2 a, Vector2 b, Vector2 c, Vector2 d,
Vector2 *out_intersection) {
// http://paulbourke.net/geometry/pointlineplane/ <-- Good stuff
Vector2 cd = d - c;
Vector2 ab = b - a;
float div = cd.y * ab.x - cd.x * ab.y;
if (Math::abs(div) > 0.001f) {
float ua = (cd.x * (a.y - c.y) - cd.y * (a.x - c.x)) / div;
float ub = (ab.x * (a.y - c.y) - ab.y * (a.x - c.x)) / div;
*out_intersection = a + ua * ab;
if (ua >= 0.f && ua <= 1.f &&
ub >= 0.f && ub <= 1.f)
return SEGMENT_INTERSECT;
return SEGMENT_NO_INTERSECT;
}
return SEGMENT_PARALLEL;
}
// TODO I'm pretty sure there is an even faster way to swap things
template <typename T>
static inline void swap(T &a, T &b) {
T tmp = a;
a = b;
b = tmp;
}
static float calculate_total_distance(const Vector<Vector2> &points) {
float d = 0.f;
for (int i = 1; i < points.size(); ++i) {
d += points[i].distance_to(points[i - 1]);
}
return d;
}
static inline Vector2 rotate90(const Vector2 &v) {
// Note: the 2D referential is X-right, Y-down
return Vector2(v.y, -v.x);
}
static inline Vector2 interpolate(const Rect2 &r, const Vector2 &v) {
return Vector2(
Math::lerp(r.position.x, r.position.x + r.get_size().x, v.x),
Math::lerp(r.position.y, r.position.y + r.get_size().y, v.y));
}
//----------------------------------------------------------------------------
// LineBuilder
//----------------------------------------------------------------------------
LineBuilder::LineBuilder() {
joint_mode = Line2D::LINE_JOINT_SHARP;
width = 10;
default_color = Color(0.4, 0.5, 1);
gradient = NULL;
sharp_limit = 2.f;
round_precision = 8;
begin_cap_mode = Line2D::LINE_CAP_NONE;
end_cap_mode = Line2D::LINE_CAP_NONE;
_interpolate_color = false;
_last_index[0] = 0;
_last_index[1] = 0;
}
void LineBuilder::clear_output() {
vertices.clear();
colors.clear();
indices.clear();
}
void LineBuilder::build() {
// Need at least 2 points to draw a line
if (points.size() < 2) {
clear_output();
return;
}
const float hw = width / 2.f;
const float hw_sq = hw * hw;
const float sharp_limit_sq = sharp_limit * sharp_limit;
const int len = points.size();
// Initial values
Vector2 pos0 = points[0];
Vector2 pos1 = points[1];
Vector2 f0 = (pos1 - pos0).normalized();
Vector2 u0 = rotate90(f0);
Vector2 pos_up0 = pos0 + u0 * hw;
Vector2 pos_down0 = pos0 - u0 * hw;
Color color0;
Color color1;
float current_distance0 = 0.f;
float current_distance1 = 0.f;
float total_distance = 0.f;
_interpolate_color = gradient != NULL;
bool distance_required = _interpolate_color || texture_mode == Line2D::LINE_TEXTURE_TILE;
if (distance_required)
total_distance = calculate_total_distance(points);
if (_interpolate_color)
color0 = gradient->get_color(0);
else
colors.push_back(default_color);
float uvx0 = 0.f;
float uvx1 = 0.f;
// Begin cap
if (begin_cap_mode == Line2D::LINE_CAP_BOX) {
// Push back first vertices a little bit
pos_up0 -= f0 * hw;
pos_down0 -= f0 * hw;
// The line's outer length will be a little higher due to begin and end caps
total_distance += width;
current_distance0 += hw;
current_distance1 = current_distance0;
} else if (begin_cap_mode == Line2D::LINE_CAP_ROUND) {
if (texture_mode == Line2D::LINE_TEXTURE_TILE) {
uvx0 = 0.5f;
}
new_arc(pos0, pos_up0 - pos0, -Math_PI, color0, Rect2(0.f, 0.f, 1.f, 1.f));
total_distance += width;
current_distance0 += hw;
current_distance1 = current_distance0;
}
strip_begin(pos_up0, pos_down0, color0, uvx0);
/*
* pos_up0 ------------- pos_up1 --------------------
* | |
* pos0 - - - - - - - - - pos1 - - - - - - - - - pos2
* | |
* pos_down0 ------------ pos_down1 ------------------
*
* i-1 i i+1
*/
// http://labs.hyperandroid.com/tag/opengl-lines
// (not the same implementation but visuals help a lot)
// For each additional segment
for (int i = 1; i < len - 1; ++i) {
pos1 = points[i];
Vector2 pos2 = points[i + 1];
Vector2 f1 = (pos2 - pos1).normalized();
Vector2 u1 = rotate90(f1);
// Determine joint orientation
const float dp = u0.dot(f1);
const Orientation orientation = (dp > 0.f ? UP : DOWN);
Vector2 inner_normal0, inner_normal1;
if (orientation == UP) {
inner_normal0 = u0 * hw;
inner_normal1 = u1 * hw;
} else {
inner_normal0 = -u0 * hw;
inner_normal1 = -u1 * hw;
}
/*
* ---------------------------
* /
* 0 / 1
* / /
* --------------------x------ /
* / / (here shown with orientation == DOWN)
* / /
* / /
* / /
* 2 /
* /
*/
// Find inner intersection at the joint
Vector2 corner_pos_in, corner_pos_out;
SegmentIntersectionResult intersection_result = segment_intersection(
pos0 + inner_normal0, pos1 + inner_normal0,
pos1 + inner_normal1, pos2 + inner_normal1,
&corner_pos_in);
if (intersection_result == SEGMENT_INTERSECT)
// Inner parts of the segments intersect
corner_pos_out = 2.f * pos1 - corner_pos_in;
else {
// No intersection, segments are either parallel or too sharp
corner_pos_in = pos1 + inner_normal0;
corner_pos_out = pos1 - inner_normal0;
}
Vector2 corner_pos_up, corner_pos_down;
if (orientation == UP) {
corner_pos_up = corner_pos_in;
corner_pos_down = corner_pos_out;
} else {
corner_pos_up = corner_pos_out;
corner_pos_down = corner_pos_in;
}
Line2D::LineJointMode current_joint_mode = joint_mode;
Vector2 pos_up1, pos_down1;
if (intersection_result == SEGMENT_INTERSECT) {
// Fallback on bevel if sharp angle is too high (because it would produce very long miters)
if (current_joint_mode == Line2D::LINE_JOINT_SHARP && corner_pos_out.distance_squared_to(pos1) / hw_sq > sharp_limit_sq) {
current_joint_mode = Line2D::LINE_JOINT_BEVEL;
}
if (current_joint_mode == Line2D::LINE_JOINT_SHARP) {
// In this case, we won't create joint geometry,
// The previous and next line quads will directly share an edge.
pos_up1 = corner_pos_up;
pos_down1 = corner_pos_down;
} else {
// Bevel or round
if (orientation == UP) {
pos_up1 = corner_pos_up;
pos_down1 = pos1 - u0 * hw;
} else {
pos_up1 = pos1 + u0 * hw;
pos_down1 = corner_pos_down;
}
}
} else {
// No intersection: fallback
pos_up1 = corner_pos_up;
pos_down1 = corner_pos_down;
}
// Add current line body quad
// Triangles are clockwise
if (distance_required) {
current_distance1 += pos0.distance_to(pos1);
}
if (_interpolate_color) {
color1 = gradient->get_color_at_offset(current_distance1 / total_distance);
}
if (texture_mode == Line2D::LINE_TEXTURE_TILE) {
uvx0 = current_distance0 / width;
uvx1 = current_distance1 / width;
}
strip_add_quad(pos_up1, pos_down1, color1, uvx1);
// Swap vars for use in the next line
color0 = color1;
u0 = u1;
f0 = f1;
pos0 = pos1;
current_distance0 = current_distance1;
if (intersection_result == SEGMENT_INTERSECT) {
if (current_joint_mode == Line2D::LINE_JOINT_SHARP) {
pos_up0 = pos_up1;
pos_down0 = pos_down1;
} else {
if (orientation == UP) {
pos_up0 = corner_pos_up;
pos_down0 = pos1 - u1 * hw;
} else {
pos_up0 = pos1 + u1 * hw;
pos_down0 = corner_pos_down;
}
}
} else {
pos_up0 = pos1 + u1 * hw;
pos_down0 = pos1 - u1 * hw;
}
// From this point, bu0 and bd0 concern the next segment
// Add joint geometry
if (current_joint_mode != Line2D::LINE_JOINT_SHARP) {
/* ________________ cbegin
* / \
* / \
* ____________/_ _ _\ cend
* | |
* | |
* | |
*/
Vector2 cbegin, cend;
if (orientation == UP) {
cbegin = pos_down1;
cend = pos_down0;
} else {
cbegin = pos_up1;
cend = pos_up0;
}
if (current_joint_mode == Line2D::LINE_JOINT_BEVEL) {
strip_add_tri(cend, orientation);
} else if (current_joint_mode == Line2D::LINE_JOINT_ROUND) {
Vector2 vbegin = cbegin - pos1;
Vector2 vend = cend - pos1;
strip_add_arc(pos1, vbegin.angle_to(vend), orientation);
}
if (intersection_result != SEGMENT_INTERSECT)
// In this case the joint is too fucked up to be re-used,
// start again the strip with fallback points
strip_begin(pos_up0, pos_down0, color1, uvx1);
}
}
// Last (or only) segment
pos1 = points[points.size() - 1];
Vector2 pos_up1 = pos1 + u0 * hw;
Vector2 pos_down1 = pos1 - u0 * hw;
// End cap (box)
if (end_cap_mode == Line2D::LINE_CAP_BOX) {
pos_up1 += f0 * hw;
pos_down1 += f0 * hw;
}
if (distance_required) {
current_distance1 += pos0.distance_to(pos1);
}
if (_interpolate_color) {
color1 = gradient->get_color(gradient->get_points_count() - 1);
}
if (texture_mode == Line2D::LINE_TEXTURE_TILE) {
uvx1 = current_distance1 / width;
}
strip_add_quad(pos_up1, pos_down1, color1, uvx1);
// End cap (round)
if (end_cap_mode == Line2D::LINE_CAP_ROUND) {
// Note: color is not used in case we don't interpolate...
Color color = _interpolate_color ? gradient->get_color(gradient->get_points_count() - 1) : Color(0, 0, 0);
new_arc(pos1, pos_up1 - pos1, Math_PI, color, Rect2(uvx1 - 0.5f, 0.f, 1.f, 1.f));
}
}
void LineBuilder::strip_begin(Vector2 up, Vector2 down, Color color, float uvx) {
int vi = vertices.size();
vertices.push_back(up);
vertices.push_back(down);
if (_interpolate_color) {
colors.push_back(color);
colors.push_back(color);
}
if (texture_mode != Line2D::LINE_TEXTURE_NONE) {
uvs.push_back(Vector2(uvx, 0.f));
uvs.push_back(Vector2(uvx, 1.f));
}
_last_index[UP] = vi;
_last_index[DOWN] = vi + 1;
}
void LineBuilder::strip_new_quad(Vector2 up, Vector2 down, Color color, float uvx) {
int vi = vertices.size();
vertices.push_back(vertices[_last_index[UP]]);
vertices.push_back(vertices[_last_index[DOWN]]);
vertices.push_back(up);
vertices.push_back(down);
if (_interpolate_color) {
colors.push_back(color);
colors.push_back(color);
colors.push_back(color);
colors.push_back(color);
}
if (texture_mode != Line2D::LINE_TEXTURE_NONE) {
uvs.push_back(uvs[_last_index[UP]]);
uvs.push_back(uvs[_last_index[DOWN]]);
uvs.push_back(Vector2(uvx, UP));
uvs.push_back(Vector2(uvx, DOWN));
}
indices.push_back(vi);
indices.push_back(vi + 3);
indices.push_back(vi + 1);
indices.push_back(vi);
indices.push_back(vi + 2);
indices.push_back(vi + 3);
_last_index[UP] = vi + 2;
_last_index[DOWN] = vi + 3;
}
void LineBuilder::strip_add_quad(Vector2 up, Vector2 down, Color color, float uvx) {
int vi = vertices.size();
vertices.push_back(up);
vertices.push_back(down);
if (_interpolate_color) {
colors.push_back(color);
colors.push_back(color);
}
if (texture_mode != Line2D::LINE_TEXTURE_NONE) {
uvs.push_back(Vector2(uvx, 0.f));
uvs.push_back(Vector2(uvx, 1.f));
}
indices.push_back(_last_index[UP]);
indices.push_back(vi + 1);
indices.push_back(_last_index[DOWN]);
indices.push_back(_last_index[UP]);
indices.push_back(vi);
indices.push_back(vi + 1);
_last_index[UP] = vi;
_last_index[DOWN] = vi + 1;
}
void LineBuilder::strip_add_tri(Vector2 up, Orientation orientation) {
int vi = vertices.size();
vertices.push_back(up);
if (_interpolate_color) {
colors.push_back(colors[colors.size() - 1]);
}
Orientation opposite_orientation = orientation == UP ? DOWN : UP;
if (texture_mode != Line2D::LINE_TEXTURE_NONE) {
// UVs are just one slice of the texture all along
// (otherwise we can't share the bottom vertice)
uvs.push_back(uvs[_last_index[opposite_orientation]]);
}
indices.push_back(_last_index[opposite_orientation]);
indices.push_back(vi);
indices.push_back(_last_index[orientation]);
_last_index[opposite_orientation] = vi;
}
void LineBuilder::strip_add_arc(Vector2 center, float angle_delta, Orientation orientation) {
// Take the two last vertices and extrude an arc made of triangles
// that all share one of the initial vertices
Orientation opposite_orientation = orientation == UP ? DOWN : UP;
Vector2 vbegin = vertices[_last_index[opposite_orientation]] - center;
float radius = vbegin.length();
float angle_step = Math_PI / static_cast<float>(round_precision);
float steps = Math::abs(angle_delta) / angle_step;
if (angle_delta < 0.f)
angle_step = -angle_step;
float t = Vector2(1, 0).angle_to(vbegin);
float end_angle = t + angle_delta;
Vector2 rpos(0, 0);
// Arc vertices
for (int ti = 0; ti < steps; ++ti, t += angle_step) {
rpos = center + Vector2(Math::cos(t), Math::sin(t)) * radius;
strip_add_tri(rpos, orientation);
}
// Last arc vertice
rpos = center + Vector2(Math::cos(end_angle), Math::sin(end_angle)) * radius;
strip_add_tri(rpos, orientation);
}
void LineBuilder::new_arc(Vector2 center, Vector2 vbegin, float angle_delta, Color color, Rect2 uv_rect) {
// Make a standalone arc that doesn't use existing vertices,
// with undistorted UVs from within a square section
float radius = vbegin.length();
float angle_step = Math_PI / static_cast<float>(round_precision);
float steps = Math::abs(angle_delta) / angle_step;
if (angle_delta < 0.f)
angle_step = -angle_step;
float t = Vector2(1, 0).angle_to(vbegin);
float end_angle = t + angle_delta;
Vector2 rpos(0, 0);
float tt_begin = -Math_PI / 2.f;
float tt = tt_begin;
// Center vertice
int vi = vertices.size();
vertices.push_back(center);
if (_interpolate_color)
colors.push_back(color);
if (texture_mode != Line2D::LINE_TEXTURE_NONE)
uvs.push_back(interpolate(uv_rect, Vector2(0.5f, 0.5f)));
// Arc vertices
for (int ti = 0; ti < steps; ++ti, t += angle_step) {
Vector2 sc = Vector2(Math::cos(t), Math::sin(t));
rpos = center + sc * radius;
vertices.push_back(rpos);
if (_interpolate_color)
colors.push_back(color);
if (texture_mode != Line2D::LINE_TEXTURE_NONE) {
Vector2 tsc = Vector2(Math::cos(tt), Math::sin(tt));
uvs.push_back(interpolate(uv_rect, 0.5f * (tsc + Vector2(1.f, 1.f))));
tt += angle_step;
}
}
// Last arc vertice
Vector2 sc = Vector2(Math::cos(end_angle), Math::sin(end_angle));
rpos = center + sc * radius;
vertices.push_back(rpos);
if (_interpolate_color)
colors.push_back(color);
if (texture_mode != Line2D::LINE_TEXTURE_NONE) {
tt = tt_begin + angle_delta;
Vector2 tsc = Vector2(Math::cos(tt), Math::sin(tt));
uvs.push_back(interpolate(uv_rect, 0.5f * (tsc + Vector2(1.f, 1.f))));
}
// Make up triangles
int vi0 = vi;
for (int ti = 0; ti < steps; ++ti) {
indices.push_back(vi0);
indices.push_back(++vi);
indices.push_back(vi + 1);
}
}
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