Mercurial > hg > orthanc-stone
view Framework/Scene2D/Internals/OpenGLLinesProgram.cpp @ 1039:3a35d8397559
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author | Alain Mazy <alain@mazy.be> |
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date | Mon, 07 Oct 2019 22:37:24 +0200 |
parents | a7351ad54960 |
children | 2d8ab34c8c91 |
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/** * Stone of Orthanc * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics * Department, University Hospital of Liege, Belgium * Copyright (C) 2017-2019 Osimis S.A., Belgium * * This program is free software: you can redistribute it and/or * modify it under the terms of the GNU Affero General Public License * as published by the Free Software Foundation, either version 3 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. **/ #include "OpenGLLinesProgram.h" #include "OpenGLShaderVersionDirective.h" #include <Core/OrthancException.h> static const unsigned int COMPONENTS_POSITION = 3; static const unsigned int COMPONENTS_COLOR = 3; static const unsigned int COMPONENTS_MITER = 2; static const char* VERTEX_SHADER = ORTHANC_STONE_OPENGL_SHADER_VERSION_DIRECTIVE "attribute vec2 a_miter_direction; \n" "attribute vec4 a_position; \n" "attribute vec3 a_color; \n" "uniform float u_thickness; \n" "uniform mat4 u_matrix; \n" "varying float v_distance; \n" "varying vec3 v_color; \n" "void main() \n" "{ \n" " v_distance = a_position.z; \n" " v_color = a_color; \n" " gl_Position = u_matrix * vec4(a_position.xy + a_position.z * a_miter_direction * u_thickness, 0, 1); \n" "}"; static const char* FRAGMENT_SHADER = ORTHANC_STONE_OPENGL_SHADER_VERSION_DIRECTIVE "uniform bool u_antialiasing; \n" "uniform float u_antialiasing_start; \n" "varying float v_distance; \n" // Distance of the point to the segment "varying vec3 v_color; \n" "void main() \n" "{ \n" " float d = abs(v_distance); \n" " if (!u_antialiasing || \n" " d <= u_antialiasing_start) \n" " gl_FragColor = vec4(v_color, 1); \n" " else if (d >= 1.0) \n" " gl_FragColor = vec4(0, 0, 0, 0); \n" " else \n" " { \n" " float alpha = 1.0 - smoothstep(u_antialiasing_start, 1.0, d); \n" " gl_FragColor = vec4(v_color * alpha, alpha); \n" " } \n" "}"; namespace OrthancStone { namespace Internals { class OpenGLLinesProgram::Data::Segment { private: bool isEmpty_; double x1_; double y1_; double x2_; double y2_; double miterX1_; double miterY1_; double miterX2_; double miterY2_; Vector lineAbove_; // In homogeneous coordinates (size = 3) Vector lineBelow_; public: Segment(const PolylineSceneLayer::Chain& chain, size_t index1, size_t index2) : isEmpty_(false) { if (index1 >= chain.size() || index2 >= chain.size()) { throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange); } else { const ScenePoint2D& p = chain[index1]; const ScenePoint2D& q = chain[index2]; x1_ = p.GetX(); y1_ = p.GetY(); x2_ = q.GetX(); y2_ = q.GetY(); const double dx = x2_ - x1_; const double dy = y2_ - y1_; const double norm = sqrt(dx * dx + dy * dy); if (LinearAlgebra::IsCloseToZero(norm)) { isEmpty_ = true; } else { isEmpty_ = false; const double normalX = -dy / norm; const double normalY = dx / norm; miterX1_ = normalX; miterY1_ = normalY; miterX2_ = normalX; miterY2_ = normalY; Vector a = LinearAlgebra::CreateVector(x1_ + normalX, y1_ + normalY, 1); Vector b = LinearAlgebra::CreateVector(x2_ + normalX, y2_ + normalY, 1); LinearAlgebra::CrossProduct(lineAbove_, a, b); a = LinearAlgebra::CreateVector(x1_ - normalX, y1_ - normalY, 1); b = LinearAlgebra::CreateVector(x2_ - normalX, y2_ - normalY, 1); LinearAlgebra::CrossProduct(lineBelow_, a, b); } } } bool IsEmpty() const { return isEmpty_; } static double ComputeSignedArea(double x1, double y1, double x2, double y2, double x3, double y3) { // This computes the signed area of a 2D triangle. This // formula is e.g. used in the sorting algorithm of Graham's // scan to compute the convex hull. // https://en.wikipedia.org/wiki/Graham_scan return (x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1); } static void CreateMiter(Segment& left, Segment& right) { if (!left.IsEmpty() && !right.IsEmpty()) { Vector above, below; LinearAlgebra::CrossProduct(above, left.lineAbove_, right.lineAbove_); LinearAlgebra::CrossProduct(below, left.lineBelow_, right.lineBelow_); if (!LinearAlgebra::IsCloseToZero(above[2]) && !LinearAlgebra::IsCloseToZero(below[2])) { // Back to inhomogeneous 2D coordinates above /= above[2]; below /= below[2]; // Check whether "above" and "below" intersection points // are on the half-plane defined by the endpoints of the // two segments. This is an indicator of whether the angle // is too acute. double s1 = ComputeSignedArea(left.x1_, left.y1_, above[0], above[1], right.x2_, right.y2_); double s2 = ComputeSignedArea(left.x1_, left.y1_, below[0], below[1], right.x2_, right.y2_); // The two signed areas must have the same sign if (s1 * s2 >= 0) { left.miterX2_ = above[0] - left.x2_; left.miterY2_ = above[1] - left.y2_; right.miterX1_ = left.miterX2_; right.miterY1_ = left.miterY2_; } } } } void AddTriangles(std::vector<float>& coords, std::vector<float>& miterDirections, std::vector<float>& colors, const Color& color) { if (isEmpty_) { LOG(ERROR) << "OpenGLLinesProgram -- AddTriangles: (isEmpty_)"; throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls); } // First triangle coords.push_back(static_cast<float>(x1_)); coords.push_back(static_cast<float>(y1_)); coords.push_back(static_cast<float>(1)); coords.push_back(static_cast<float>(x2_)); coords.push_back(static_cast<float>(y2_)); coords.push_back(static_cast<float>(-1)); coords.push_back(static_cast<float>(x2_)); coords.push_back(static_cast<float>(y2_)); coords.push_back(static_cast<float>(1)); miterDirections.push_back(static_cast<float>(miterX1_)); miterDirections.push_back(static_cast<float>(miterY1_)); miterDirections.push_back(static_cast<float>(miterX2_)); miterDirections.push_back(static_cast<float>(miterY2_)); miterDirections.push_back(static_cast<float>(miterX2_)); miterDirections.push_back(static_cast<float>(miterY2_)); // Second triangle coords.push_back(static_cast<float>(x1_)); coords.push_back(static_cast<float>(y1_)); coords.push_back(static_cast<float>(1)); coords.push_back(static_cast<float>(x1_)); coords.push_back(static_cast<float>(y1_)); coords.push_back(static_cast<float>(-1)); coords.push_back(static_cast<float>(x2_)); coords.push_back(static_cast<float>(y2_)); coords.push_back(static_cast<float>(-1)); miterDirections.push_back(static_cast<float>(miterX1_)); miterDirections.push_back(static_cast<float>(miterY1_)); miterDirections.push_back(static_cast<float>(miterX1_)); miterDirections.push_back(static_cast<float>(miterY1_)); miterDirections.push_back(static_cast<float>(miterX2_)); miterDirections.push_back(static_cast<float>(miterY2_)); // Add the colors of the 2 triangles (leading to 2 * 3 values) for (unsigned int i = 0; i < 6; i++) { colors.push_back(color.GetRedAsFloat()); colors.push_back(color.GetGreenAsFloat()); colors.push_back(color.GetBlueAsFloat()); } } }; OpenGLLinesProgram::Data::Data(OpenGL::IOpenGLContext& context, const PolylineSceneLayer& layer) : context_(context), verticesCount_(0), thickness_(static_cast<float>(layer.GetThickness())) { if (!context_.IsContextLost()) { // High-level reference: // https://mattdesl.svbtle.com/drawing-lines-is-hard // https://forum.libcinder.org/topic/smooth-thick-lines-using-geometry-shader size_t countVertices = 0; for (size_t i = 0; i < layer.GetChainsCount(); i++) { size_t countSegments = layer.GetChain(i).size() - 1; if (layer.IsClosedChain(i)) { countSegments++; } // Each segment is made of 2 triangles. One triangle is // defined by 3 points in 2D => 6 vertices per segment. countVertices += countSegments * 2 * 3; } std::vector<float> coords, colors, miterDirections; coords.reserve(countVertices * COMPONENTS_POSITION); colors.reserve(countVertices * COMPONENTS_COLOR); miterDirections.reserve(countVertices * COMPONENTS_MITER); for (size_t i = 0; i < layer.GetChainsCount(); i++) { const PolylineSceneLayer::Chain& chain = layer.GetChain(i); if (chain.size() > 1) { std::vector<Segment> segments; for (size_t j = 1; j < chain.size(); j++) { segments.push_back(Segment(chain, j - 1, j)); } if (layer.IsClosedChain(i)) { segments.push_back(Segment(chain, chain.size() - 1, 0)); } // Try and create nice miters for (size_t j = 1; j < segments.size(); j++) { Segment::CreateMiter(segments[j - 1], segments[j]); } if (layer.IsClosedChain(i)) { Segment::CreateMiter(segments.back(), segments.front()); } for (size_t j = 0; j < segments.size(); j++) { if (!segments[j].IsEmpty()) { segments[j].AddTriangles(coords, miterDirections, colors, layer.GetColor(i)); } } } } assert(coords.size() == colors.size()); if (!coords.empty()) { verticesCount_ = coords.size() / COMPONENTS_POSITION; context_.MakeCurrent(); glGenBuffers(3, buffers_); glBindBuffer(GL_ARRAY_BUFFER, buffers_[0]); glBufferData(GL_ARRAY_BUFFER, sizeof(float) * coords.size(), &coords[0], GL_STATIC_DRAW); glBindBuffer(GL_ARRAY_BUFFER, buffers_[1]); glBufferData(GL_ARRAY_BUFFER, sizeof(float) * miterDirections.size(), &miterDirections[0], GL_STATIC_DRAW); glBindBuffer(GL_ARRAY_BUFFER, buffers_[2]); glBufferData(GL_ARRAY_BUFFER, sizeof(float) * colors.size(), &colors[0], GL_STATIC_DRAW); } } } OpenGLLinesProgram::Data::~Data() { if (!context_.IsContextLost() && !IsEmpty()) { context_.MakeCurrent(); ORTHANC_OPENGL_TRACE_CURRENT_CONTEXT("About to call glDeleteBuffers"); glDeleteBuffers(3, buffers_); } } GLuint OpenGLLinesProgram::Data::GetVerticesBuffer() const { if (IsEmpty()) { LOG(ERROR) << "OpenGLLinesProgram::Data::GetVerticesBuffer(): (IsEmpty())"; throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls); } else { return buffers_[0]; } } GLuint OpenGLLinesProgram::Data::GetMiterDirectionsBuffer() const { if (IsEmpty()) { LOG(ERROR) << "OpenGLLinesProgram::Data::GetMiterDirectionsBuffer(): (IsEmpty())"; throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls); } else { return buffers_[1]; } } GLuint OpenGLLinesProgram::Data::GetColorsBuffer() const { if (IsEmpty()) { LOG(ERROR) << "OpenGLLinesProgram::Data::GetColorsBuffer(): (IsEmpty())"; throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls); } else { return buffers_[2]; } } OpenGLLinesProgram::OpenGLLinesProgram(OpenGL::IOpenGLContext& context) : context_(context) { if (!context_.IsContextLost()) { context_.MakeCurrent(); program_.reset(new OpenGL::OpenGLProgram(context_)); program_->CompileShaders(VERTEX_SHADER, FRAGMENT_SHADER); } } void OpenGLLinesProgram::Apply(const Data& data, const AffineTransform2D& transform, bool antialiasing, bool scaleIndependantThickness) { if (!context_.IsContextLost() && !data.IsEmpty()) { context_.MakeCurrent(); program_->Use(); GLint locationPosition = program_->GetAttributeLocation("a_position"); GLint locationMiterDirection = program_->GetAttributeLocation("a_miter_direction"); GLint locationColor = program_->GetAttributeLocation("a_color"); float m[16]; transform.ConvertToOpenGLMatrix(m, context_.GetCanvasWidth(), context_.GetCanvasHeight()); glUniformMatrix4fv(program_->GetUniformLocation("u_matrix"), 1, GL_FALSE, m); glBindBuffer(GL_ARRAY_BUFFER, data.GetVerticesBuffer()); glEnableVertexAttribArray(locationPosition); glVertexAttribPointer(locationPosition, COMPONENTS_POSITION, GL_FLOAT, GL_FALSE, 0, 0); glBindBuffer(GL_ARRAY_BUFFER, data.GetMiterDirectionsBuffer()); glEnableVertexAttribArray(locationMiterDirection); glVertexAttribPointer(locationMiterDirection, COMPONENTS_MITER, GL_FLOAT, GL_FALSE, 0, 0); glBindBuffer(GL_ARRAY_BUFFER, data.GetColorsBuffer()); glEnableVertexAttribArray(locationColor); glVertexAttribPointer(locationColor, COMPONENTS_COLOR, GL_FLOAT, GL_FALSE, 0, 0); glUniform1i(program_->GetUniformLocation("u_antialiasing"), (antialiasing ? 1 : 0)); const double zoom = transform.ComputeZoom(); const double thickness = data.GetThickness() / 2.0; const double aliasingBorder = 2.0; // Border for antialiasing ramp, in pixels assert(aliasingBorder > 0); // Prevent division by zero with "t1" if (scaleIndependantThickness) { if (antialiasing) { double t1 = std::max(thickness, aliasingBorder); double t0 = std::max(0.0, thickness - aliasingBorder); glUniform1f(program_->GetUniformLocation("u_thickness"), static_cast<GLfloat>(t1 / zoom)); glUniform1f(program_->GetUniformLocation("u_antialiasing_start"), static_cast<GLfloat>(t0 / t1)); } else { glUniform1f(program_->GetUniformLocation("u_thickness"), static_cast<GLfloat>(thickness / zoom)); } } else { if (antialiasing) { double t1 = std::max(thickness, aliasingBorder / zoom); double t0 = std::max(0.0, thickness - aliasingBorder / zoom); glUniform1f(program_->GetUniformLocation("u_thickness"), static_cast<GLfloat>(t1)); glUniform1f(program_->GetUniformLocation("u_antialiasing_start"), static_cast<GLfloat>(t0 / t1)); } else { glUniform1f(program_->GetUniformLocation("u_thickness"), static_cast<GLfloat>(thickness)); } } if (antialiasing) { glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA); glDrawArrays(GL_TRIANGLES, 0, static_cast<GLsizei>(data.GetVerticesCount())); glDisable(GL_BLEND); } else { glDrawArrays(GL_TRIANGLES, 0, static_cast<GLsizei>(data.GetVerticesCount())); } glDisableVertexAttribArray(locationPosition); glDisableVertexAttribArray(locationMiterDirection); glDisableVertexAttribArray(locationColor); } } } }