Draw a triangle on the map

scwx-qt/source/scwx/qt/map/triangle_layer.cpp

@@ -0,0 +1,167 @@
+#include <scwx/qt/map/triangle_layer.hpp>
+
+#include <QOpenGLFunctions_3_3_Core>
+
+#include <boost/log/trivial.hpp>
+
+namespace scwx
+{
+namespace qt
+{
+
+static const std::string logPrefix_ = "[scwx::map::triangle_layer] ";
+
+class TriangleLayerImpl
+{
+public:
+   explicit TriangleLayerImpl() :
+       gl_(),
+       shaderProgram_ {GL_INVALID_INDEX},
+       vbo_ {GL_INVALID_INDEX},
+       vao_ {GL_INVALID_INDEX}
+   {
+      gl_.initializeOpenGLFunctions();
+   }
+   ~TriangleLayerImpl() = default;
+
+   QOpenGLFunctions_3_3_Core gl_;
+
+   GLuint shaderProgram_;
+   GLuint vbo_;
+   GLuint vao_;
+};
+
+TriangleLayer::TriangleLayer() : p(std::make_unique<TriangleLayerImpl>()) {}
+TriangleLayer::~TriangleLayer() = default;
+
+TriangleLayer::TriangleLayer(TriangleLayer&&) noexcept = default;
+TriangleLayer& TriangleLayer::operator=(TriangleLayer&&) noexcept = default;
+
+void TriangleLayer::initialize()
+{
+   QOpenGLFunctions_3_3_Core& gl = p->gl_;
+
+   static const char* vertexShaderSource =
+      "#version 330 core\n"
+      "layout (location = 0) in vec3 aPos;"
+      "void main()"
+      "{"
+      "   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);"
+      "}";
+
+   static const char* fragmentShaderSource =
+      "#version 330 core\n"
+      "out vec4 FragColor;"
+      "void main()"
+      "{"
+      "   FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);"
+      "}";
+
+   BOOST_LOG_TRIVIAL(debug) << logPrefix_ << "initialize()";
+
+   GLint success;
+
+   // Create a vertex shader
+   GLuint vertexShader = gl.glCreateShader(GL_VERTEX_SHADER);
+
+   // Attach the shader source code and compile the shader
+   gl.glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
+   gl.glCompileShader(vertexShader);
+
+   // Check for errors
+   gl.glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
+   if (!success)
+   {
+      char infoLog[512];
+      gl.glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
+      BOOST_LOG_TRIVIAL(error)
+         << logPrefix_ << "Vertex shader compilation failed";
+   }
+
+   // Create a fragment shader
+   GLuint fragmentShader = gl.glCreateShader(GL_FRAGMENT_SHADER);
+
+   // Attach the shader source and compile the shader
+   gl.glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
+   gl.glCompileShader(fragmentShader);
+
+   // Check for errors
+   gl.glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
+   if (!success)
+   {
+      char infoLog[512];
+      gl.glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
+      BOOST_LOG_TRIVIAL(error)
+         << logPrefix_ << "Fragment shader compilation failed: " << infoLog;
+   }
+
+   // Create shader program
+   p->shaderProgram_ = gl.glCreateProgram();
+
+   gl.glAttachShader(p->shaderProgram_, vertexShader);
+   gl.glAttachShader(p->shaderProgram_, fragmentShader);
+   gl.glLinkProgram(p->shaderProgram_);
+
+   // Check for errors
+   gl.glGetProgramiv(p->shaderProgram_, GL_LINK_STATUS, &success);
+   if (!success)
+   {
+      char infoLog[512];
+      gl.glGetProgramInfoLog(p->shaderProgram_, 512, NULL, infoLog);
+      BOOST_LOG_TRIVIAL(error)
+         << logPrefix_ << "Shader program link failed: " << infoLog;
+   }
+
+   // Delete shaders
+   gl.glDeleteShader(vertexShader);
+   gl.glDeleteShader(fragmentShader);
+
+   // Define 3 (x,y,z) vertices
+   GLfloat vertices[] = {
+      -0.5f, -0.5f, 0.0f, 0.5f, -0.5f, 0.0f, 0.0f, 0.5f, 0.0f};
+
+   // Generate a vertex buffer object
+   gl.glGenBuffers(1, &p->vbo_);
+
+   // Generate a vertex array object
+   gl.glGenVertexArrays(1, &p->vao_);
+
+   // Bind vertex array object
+   gl.glBindVertexArray(p->vao_);
+
+   // Copy vertices array in a buffer for OpenGL to use
+   gl.glBindBuffer(GL_ARRAY_BUFFER, p->vbo_);
+   gl.glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+   // Set the vertex attributes pointers
+   gl.glVertexAttribPointer(
+      0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), static_cast<void*>(0));
+   gl.glEnableVertexAttribArray(0);
+}
+
+void TriangleLayer::render(const QMapbox::CustomLayerRenderParameters&)
+{
+   QOpenGLFunctions_3_3_Core& gl = p->gl_;
+
+   gl.glUseProgram(p->shaderProgram_);
+   gl.glBindVertexArray(p->vao_);
+   gl.glDrawArrays(GL_TRIANGLES, 0, 3);
+}
+
+void TriangleLayer::deinitialize()
+{
+   QOpenGLFunctions_3_3_Core& gl = p->gl_;
+
+   BOOST_LOG_TRIVIAL(debug) << logPrefix_ << "deinitialize()";
+
+   gl.glDeleteProgram(p->shaderProgram_);
+   gl.glDeleteVertexArrays(1, &p->vao_);
+   gl.glDeleteBuffers(1, &p->vbo_);
+
+   p->shaderProgram_ = GL_INVALID_INDEX;
+   p->vao_           = GL_INVALID_INDEX;
+   p->vbo_           = GL_INVALID_INDEX;
+}
+
+} // namespace qt
+} // namespace scwx