e2fba10b95
It supports unlimited width, color gradient, texture and some geometry options for joints and caps. Also transparency without artifacts (provided that line joints aren't too sharp).
564 lines
15 KiB
C++
564 lines
15 KiB
C++
#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.get_pos().x, r.get_pos().x + r.get_size().x, v.x),
|
|
Math::lerp(r.get_pos().y, r.get_pos().y + r.get_size().y, v.y)
|
|
);
|
|
}
|
|
|
|
//----------------------------------------------------------------------------
|
|
// LineBuilder
|
|
//----------------------------------------------------------------------------
|
|
|
|
LineBuilder::LineBuilder() {
|
|
joint_mode = 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 = LINE_CAP_NONE;
|
|
end_cap_mode = 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;
|
|
_interpolate_color = gradient != NULL;
|
|
bool distance_required = _interpolate_color || texture_mode == 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 == 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 == LINE_CAP_ROUND) {
|
|
if(texture_mode == 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;
|
|
}
|
|
|
|
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 == LINE_JOINT_SHARP && corner_pos_out.distance_squared_to(pos1) / hw_sq > sharp_limit_sq) {
|
|
current_joint_mode = LINE_JOINT_BEVEL;
|
|
}
|
|
if(current_joint_mode == 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 == 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 == 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 != 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 == LINE_JOINT_BEVEL) {
|
|
strip_add_tri(cend, orientation);
|
|
}
|
|
else if(current_joint_mode == LINE_JOINT_ROUND) {
|
|
Vector2 vbegin = cbegin - pos1;
|
|
Vector2 vend = cend - pos1;
|
|
strip_add_arc(pos1, vend.angle_to(vbegin), 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 == 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 == LINE_TEXTURE_TILE) {
|
|
uvx1 = current_distance1 / width;
|
|
}
|
|
|
|
strip_add_quad(pos_up1, pos_down1, color1, uvx1);
|
|
|
|
// End cap (round)
|
|
if(end_cap_mode == 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 != 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 != 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 != 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 != 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 = vbegin.angle_to(Vector2(1, 0));
|
|
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 withing 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 = vbegin.angle_to(Vector2(1, 0));
|
|
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 != 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 != 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 != 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);
|
|
}
|
|
}
|
|
|
|
|