/*************************************************************************/ /* 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 = 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 = 0.f; _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, 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 == 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 = 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 != 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); } }