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virtualx-engine/scene/2d/line_builder.cpp
Rémi Verschelde a7f49ac9a1 Update copyright statements to 2020 
Happy new year to the wonderful Godot community!

We're starting a new decade with a well-established, non-profit, free
and open source game engine, and tons of further improvements in the
pipeline from hundreds of contributors.

Godot will keep getting better, and we're looking forward to all the
games that the community will keep developing and releasing with it.
2020-01-01 11:16:22 +01:00

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/*************************************************************************/
/* line_builder.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2020 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;
curve = NULL;
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;
tile_aspect = 1.f;
_interpolate_color = false;
_last_index[0] = 0;
_last_index[1] = 0;
}
void LineBuilder::clear_output() {
vertices.clear();
colors.clear();
indices.clear();
uvs.clear();
}
void LineBuilder::build() {
// Need at least 2 points to draw a line
if (points.size() < 2) {
clear_output();
return;
}
ERR_FAIL_COND(tile_aspect <= 0.f);
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;
Vector2 pos_down0 = pos0;
Color color0;
Color color1;
float current_distance0 = 0.f;
float current_distance1 = 0.f;
float total_distance = 0.f;
float width_factor = 1.f;
_interpolate_color = gradient != NULL;
bool retrieve_curve = curve != NULL;
bool distance_required = _interpolate_color ||
retrieve_curve ||
texture_mode == Line2D::LINE_TEXTURE_TILE ||
texture_mode == Line2D::LINE_TEXTURE_STRETCH;
if (distance_required) {
total_distance = calculate_total_distance(points);
//Adjust totalDistance.
// The line's outer length will be a little higher due to begin and end caps
if (begin_cap_mode == Line2D::LINE_CAP_BOX || begin_cap_mode == Line2D::LINE_CAP_ROUND) {
if (retrieve_curve)
total_distance += width * curve->interpolate_baked(0.f) * 0.5f;
else
total_distance += width * 0.5f;
}
if (end_cap_mode == Line2D::LINE_CAP_BOX || end_cap_mode == Line2D::LINE_CAP_ROUND) {
if (retrieve_curve)
total_distance += width * curve->interpolate_baked(1.f) * 0.5f;
else
total_distance += width * 0.5f;
}
}
if (_interpolate_color)
color0 = gradient->get_color(0);
else
colors.push_back(default_color);
float uvx0 = 0.f;
float uvx1 = 0.f;
if (retrieve_curve)
width_factor = curve->interpolate_baked(0.f);
pos_up0 += u0 * hw * width_factor;
pos_down0 -= u0 * hw * width_factor;
// Begin cap
if (begin_cap_mode == Line2D::LINE_CAP_BOX) {
// Push back first vertices a little bit
pos_up0 -= f0 * hw * width_factor;
pos_down0 -= f0 * hw * width_factor;
current_distance0 += hw * width_factor;
current_distance1 = current_distance0;
} else if (begin_cap_mode == Line2D::LINE_CAP_ROUND) {
if (texture_mode == Line2D::LINE_TEXTURE_TILE) {
uvx0 = width_factor * 0.5f / tile_aspect;
} else if (texture_mode == Line2D::LINE_TEXTURE_STRETCH) {
uvx0 = width * width_factor / total_distance;
}
new_arc(pos0, pos_up0 - pos0, -Math_PI, color0, Rect2(0.f, 0.f, uvx0 * 2, 1.f));
current_distance0 += hw * width_factor;
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);
if (distance_required) {
current_distance1 += pos0.distance_to(pos1);
}
if (_interpolate_color) {
color1 = gradient->get_color_at_offset(current_distance1 / total_distance);
}
if (retrieve_curve) {
width_factor = curve->interpolate_baked(current_distance1 / total_distance);
}
Vector2 inner_normal0, inner_normal1;
if (orientation == UP) {
inner_normal0 = u0 * hw * width_factor;
inner_normal1 = u1 * hw * width_factor;
} else {
inner_normal0 = -u0 * hw * width_factor;
inner_normal1 = -u1 * hw * width_factor;
}
/*
* ---------------------------
* /
* 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)
float width_factor_sq = width_factor * width_factor;
if (current_joint_mode == Line2D::LINE_JOINT_SHARP && corner_pos_out.distance_squared_to(pos1) / (hw_sq * width_factor_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 * width_factor;
} else {
pos_up1 = pos1 + u0 * hw * width_factor;
pos_down1 = corner_pos_down;
}
}
} else {
// No intersection: fallback
if (current_joint_mode == Line2D::LINE_JOINT_SHARP) {
// There is no fallback implementation for LINE_JOINT_SHARP so switch to the LINE_JOINT_BEVEL
current_joint_mode = Line2D::LINE_JOINT_BEVEL;
}
pos_up1 = corner_pos_up;
pos_down1 = corner_pos_down;
}
// Add current line body quad
// Triangles are clockwise
if (texture_mode == Line2D::LINE_TEXTURE_TILE) {
uvx1 = current_distance1 / (width * tile_aspect);
} else if (texture_mode == Line2D::LINE_TEXTURE_STRETCH) {
uvx1 = current_distance1 / total_distance;
}
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;
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 * width_factor;
} else {
pos_up0 = pos1 + u1 * hw * width_factor;
pos_down0 = corner_pos_down;
}
}
} else {
pos_up0 = pos1 + u1 * hw * width_factor;
pos_down0 = pos1 - u1 * hw * width_factor;
}
// 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 corrputed 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];
if (distance_required) {
current_distance1 += pos0.distance_to(pos1);
}
if (_interpolate_color) {
color1 = gradient->get_color(gradient->get_points_count() - 1);
}
if (retrieve_curve) {
width_factor = curve->interpolate_baked(1.f);
}
Vector2 pos_up1 = pos1 + u0 * hw * width_factor;
Vector2 pos_down1 = pos1 - u0 * hw * width_factor;
// End cap (box)
if (end_cap_mode == Line2D::LINE_CAP_BOX) {
pos_up1 += f0 * hw * width_factor;
pos_down1 += f0 * hw * width_factor;
}
if (texture_mode == Line2D::LINE_TEXTURE_TILE) {
uvx1 = current_distance1 / (width * tile_aspect);
} else if (texture_mode == Line2D::LINE_TEXTURE_STRETCH) {
uvx1 = current_distance1 / total_distance;
}
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);
float dist = 0;
if (texture_mode == Line2D::LINE_TEXTURE_TILE) {
dist = width_factor / tile_aspect;
} else if (texture_mode == Line2D::LINE_TEXTURE_STRETCH) {
dist = width * width_factor / total_distance;
}
new_arc(pos1, pos_up1 - pos1, Math_PI, color, Rect2(uvx1 - 0.5f * dist, 0.f, dist, 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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