diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt index a2b7136f..3e078ced 100644 --- a/examples/CMakeLists.txt +++ b/examples/CMakeLists.txt @@ -26,6 +26,15 @@ set_target_properties( LIBRARY_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/out/${CMAKE_BUILD_TYPE}" RUNTIME_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/out/${CMAKE_BUILD_TYPE}") +add_executable(example_barycentric example_barycentric.cpp) +set_target_properties( + example_barycentric + PROPERTIES CXX_STANDARD 23 + ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/out/${CMAKE_BUILD_TYPE}" + LIBRARY_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/out/${CMAKE_BUILD_TYPE}" + RUNTIME_OUTPUT_DIRECTORY "${CMAKE_SOURCE_DIR}/out/${CMAKE_BUILD_TYPE}") +target_link_libraries(example_barycentric PRIVATE omath::omath GLEW::GLEW glfw OpenGL::GL) + find_package(OpenGL) find_package(GLEW REQUIRED) find_package(glfw3 CONFIG REQUIRED) diff --git a/examples/example_barycentric.cpp b/examples/example_barycentric.cpp new file mode 100644 index 00000000..9c9a3808 --- /dev/null +++ b/examples/example_barycentric.cpp @@ -0,0 +1,332 @@ +#include +#include +#include +#include +#include +#include + +using omath::Vector3; +using omath::Triangle; +using omath::Color; + +static const char* vertexShaderSource = R"( +#version 330 core +layout (location = 0) in vec3 aPos; +layout (location = 1) in vec3 aColor; +layout (location = 2) in float aPointSize; +layout (location = 3) in float aIsLine; + +out vec3 vColor; +out float vIsLine; + +void main() { + gl_Position = vec4(aPos, 1.0); + vColor = aColor; + gl_PointSize = aPointSize; + vIsLine = aIsLine; +} +)"; + +static const char* fragmentShaderSource = R"( +#version 330 core +in vec3 vColor; +in float vIsLine; +out vec4 FragColor; + +void main() { + if (vIsLine < 0.5) { + // Calculate distance from center of the point + vec2 coord = gl_PointCoord - vec2(0.5); + if(length(coord) > 0.5) + discard; + } + + FragColor = vec4(vColor, 1.0); +} +)"; + +GLuint compileShader(GLenum type, const char* src) { + GLuint shader = glCreateShader(type); + glShaderSource(shader, 1, &src, nullptr); + glCompileShader(shader); + GLint ok; + glGetShaderiv(shader, GL_COMPILE_STATUS, &ok); + if (!ok) { + char log[1024]; + glGetShaderInfoLog(shader, sizeof(log), nullptr, log); + std::cerr << "Shader error: " << log << std::endl; + } + return shader; +} + +void drawChar(char c, float x, float y, float scale, const Color& color, std::vector& lines) { + float w = 0.5f * scale; + float h = 1.0f * scale; + + auto add = [&](float x1, float y1, float x2, float y2) { + lines.push_back(x + x1*w); lines.push_back(y + y1*h); lines.push_back(0.0f); + lines.push_back(color.x); lines.push_back(color.y); lines.push_back(color.z); + lines.push_back(1.0f); // size + lines.push_back(1.0f); // isLine + + lines.push_back(x + x2*w); lines.push_back(y + y2*h); lines.push_back(0.0f); + lines.push_back(color.x); lines.push_back(color.y); lines.push_back(color.z); + lines.push_back(1.0f); // size + lines.push_back(1.0f); // isLine + }; + + switch(c) { + case '0': add(0,0, 1,0); add(1,0, 1,1); add(1,1, 0,1); add(0,1, 0,0); break; + case '1': add(0.5f,0, 0.5f,1); add(0.25f,0.75f, 0.5f,1); add(0.25f,0, 0.75f,0); break; + case '2': add(0,1, 1,1); add(1,1, 1,0.5f); add(1,0.5f, 0,0.5f); add(0,0.5f, 0,0); add(0,0, 1,0); break; + case '3': add(0,1, 1,1); add(1,1, 1,0); add(1,0, 0,0); add(0,0.5f, 1,0.5f); break; + case '4': add(0,1, 0,0.5f); add(0,0.5f, 1,0.5f); add(1,1, 1,0); break; + case '5': add(1,1, 0,1); add(0,1, 0,0.5f); add(0,0.5f, 1,0.5f); add(1,0.5f, 1,0); add(1,0, 0,0); break; + case '6': add(1,1, 0,1); add(0,1, 0,0); add(0,0, 1,0); add(1,0, 1,0.5f); add(1,0.5f, 0,0.5f); break; + case '7': add(0,1, 1,1); add(1,1, 0.5f,0); break; + case '8': add(0,0, 1,0); add(1,0, 1,1); add(1,1, 0,1); add(0,1, 0,0); add(0,0.5f, 1,0.5f); break; + case '9': add(1,0.5f, 0,0.5f); add(0,0.5f, 0,1); add(0,1, 1,1); add(1,1, 1,0); add(1,0, 0,0); break; + case '.': add(0.4f,0, 0.6f,0); add(0.6f,0, 0.6f,0.2f); add(0.6f,0.2f, 0.4f,0.2f); add(0.4f,0.2f, 0.4f,0); break; + } +} + +void drawText(const std::string& text, float x, float y, float scale, const Color& color, std::vector& lines) { + float cursor = x; + for (char c : text) { + drawChar(c, cursor, y, scale, color, lines); + cursor += (c == '.' ? 0.3f : 0.7f) * scale; + } +} + +GLFWwindow* initWindow(int width, int height, const char* title) { + if (!glfwInit()) { + std::cerr << "Failed to initialize GLFW\n"; + return nullptr; + } + + glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); + glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); + glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); + + GLFWwindow* window = glfwCreateWindow(width, height, title, NULL, NULL); + if (!window) { + std::cerr << "Failed to create GLFW window\n"; + glfwTerminate(); + return nullptr; + } + glfwMakeContextCurrent(window); + + // Check if context is valid using standard GL + const GLubyte* renderer = glGetString(GL_RENDERER); + const GLubyte* version = glGetString(GL_VERSION); + if (renderer && version) { + std::cout << "Renderer: " << renderer << "\n"; + std::cout << "OpenGL version supported: " << version << "\n"; + } else { + std::cerr << "Failed to get GL_RENDERER or GL_VERSION. Context might be invalid.\n"; + } + + glewExperimental = GL_TRUE; + GLenum glewErr = glewInit(); + if (glewErr != GLEW_OK) { + // Ignore GLEW_ERROR_NO_GLX_DISPLAY if we have a valid context (e.g. Wayland) + if (glewErr == GLEW_ERROR_NO_GLX_DISPLAY && renderer) { + std::cerr << "GLEW warning: " << glewGetErrorString(glewErr) << " (Ignored because context seems valid)\n"; + } else { + std::cerr << "Failed to initialize GLEW: " << glewGetErrorString(glewErr) << "\n"; + glfwTerminate(); + return nullptr; + } + } + return window; +} + +GLuint createShaderProgram() { + GLuint vs = compileShader(GL_VERTEX_SHADER, vertexShaderSource); + GLuint fs = compileShader(GL_FRAGMENT_SHADER, fragmentShaderSource); + GLuint shaderProgram = glCreateProgram(); + glAttachShader(shaderProgram, vs); + glAttachShader(shaderProgram, fs); + glLinkProgram(shaderProgram); + return shaderProgram; +} + +void generatePointCloud(std::vector& pointCloud, const Triangle>& triangle) { + const auto& A = triangle.m_vertex1; + const auto& B = triangle.m_vertex2; + const auto& C = triangle.m_vertex3; + // Iterating over barycentric coordinates (u, v, w) from 0.0 to 1.0 + for (float u = 0.0f; u <= 1.0f; u += 0.015f) { + for (float v = 0.0f; v <= 1.0f - u; v += 0.015f) { + float w = 1.0f - u - v; + if (w >= 0.0f && w <= 1.0f) { + Vector3 P = A * u + B * v + C * w; + pointCloud.push_back(P.x); pointCloud.push_back(P.y); pointCloud.push_back(P.z); + pointCloud.push_back(u); pointCloud.push_back(v); pointCloud.push_back(w); + pointCloud.push_back(2.0f); // size + pointCloud.push_back(0.0f); // isLine + } + } + } +} + +void setupBuffers(GLuint& VAO_cloud, GLuint& VBO_cloud, const std::vector& pointCloud, GLuint& VAO_dyn, GLuint& VBO_dyn) { + glGenVertexArrays(1, &VAO_cloud); + glGenBuffers(1, &VBO_cloud); + glBindVertexArray(VAO_cloud); + glBindBuffer(GL_ARRAY_BUFFER, VBO_cloud); + glBufferData(GL_ARRAY_BUFFER, pointCloud.size() * sizeof(float), pointCloud.data(), GL_STATIC_DRAW); + glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0); + glEnableVertexAttribArray(0); + glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float))); + glEnableVertexAttribArray(1); + glVertexAttribPointer(2, 1, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float))); + glEnableVertexAttribArray(2); + glVertexAttribPointer(3, 1, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(7 * sizeof(float))); + glEnableVertexAttribArray(3); + + glGenVertexArrays(1, &VAO_dyn); + glGenBuffers(1, &VBO_dyn); + glBindVertexArray(VAO_dyn); + glBindBuffer(GL_ARRAY_BUFFER, VBO_dyn); + glBufferData(GL_ARRAY_BUFFER, 1000 * 8 * sizeof(float), NULL, GL_DYNAMIC_DRAW); + glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0); + glEnableVertexAttribArray(0); + glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float))); + glEnableVertexAttribArray(1); + glVertexAttribPointer(2, 1, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float))); + glEnableVertexAttribArray(2); + glVertexAttribPointer(3, 1, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(7 * sizeof(float))); + glEnableVertexAttribArray(3); +} + +void updateDynamicData(std::vector& dynData, float u, float v, float w, const Vector3& P, const Triangle>& triangle) { + const auto& A = triangle.m_vertex1; + const auto& B = triangle.m_vertex2; + const auto& C = triangle.m_vertex3; + + float sizeA = 10.0f + u * 30.0f; + float sizeB = 10.0f + v * 30.0f; + float sizeC = 10.0f + w * 30.0f; + float sizeP = 12.0f; + + dynData = { + // Lines from P to A, B, C + P.x, P.y, P.z, u, v, w, 1.0f, 1.0f, + A.x, A.y, A.z, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, + + P.x, P.y, P.z, u, v, w, 1.0f, 1.0f, + B.x, B.y, B.z, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, + + P.x, P.y, P.z, u, v, w, 1.0f, 1.0f, + C.x, C.y, C.z, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, + + // The animated dot itself (White) + P.x, P.y, P.z, 1.0f, 1.0f, 1.0f, sizeP, 0.0f, + + // The 3 corner dots + A.x, A.y, A.z, 1.0f, 0.0f, 0.0f, sizeA, 0.0f, + B.x, B.y, B.z, 0.0f, 1.0f, 0.0f, sizeB, 0.0f, + C.x, C.y, C.z, 0.0f, 0.0f, 1.0f, sizeC, 0.0f + }; + + char bufA[16], bufB[16], bufC[16]; + snprintf(bufA, sizeof(bufA), "%.2f", u); + snprintf(bufB, sizeof(bufB), "%.2f", v); + snprintf(bufC, sizeof(bufC), "%.2f", w); + + // Keep text at a fixed distance from the dots + float distA = 0.13f; + float distB = 0.13f; + float distC = 0.13f; + + drawText(bufA, A.x - 0.05f, A.y + distA, 0.1f, Color(1,0,0,1), dynData); + drawText(bufB, B.x - 0.15f - distB, B.y - 0.05f - distB, 0.1f, Color(0,1,0,1), dynData); + drawText(bufC, C.x + 0.05f + distC, C.y - 0.05f - distC, 0.1f, Color(0,0,1,1), dynData); +} + +int main() { + GLFWwindow* window = initWindow(800, 800, "Barycentric Coordinates"); + if (!window) return -1; + + GLuint shaderProgram = createShaderProgram(); + + // Triangle vertices as shown in the picture (Red, Green, Blue) + // Scaled down slightly to leave room for text + Triangle> triangle( + Vector3(0.0f, 0.6f, 0.0f), // Red dot (top) + Vector3(-0.6f, -0.6f, 0.0f), // Green dot (bottom left) + Vector3(0.6f, -0.6f, 0.0f) // Blue dot (bottom right) + ); + + std::vector pointCloud; + generatePointCloud(pointCloud, triangle); + + GLuint VAO_cloud, VBO_cloud, VAO_dyn, VBO_dyn; + setupBuffers(VAO_cloud, VBO_cloud, pointCloud, VAO_dyn, VBO_dyn); + + glEnable(GL_PROGRAM_POINT_SIZE); + glEnable(GL_BLEND); + glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); + + while (!glfwWindowShouldClose(window)) { + glClearColor(0.02f, 0.02f, 0.02f, 1.0f); + glClear(GL_COLOR_BUFFER_BIT); + + glUseProgram(shaderProgram); + + // Draw the point cloud (the iterated points) + glBindVertexArray(VAO_cloud); + glDrawArrays(GL_POINTS, 0, pointCloud.size() / 8); + + // Animate the white dot to simulate dragging + float t = glfwGetTime(); + float u = (std::sin(t * 1.5f) * 0.5f + 0.5f); + float v = (std::cos(t * 1.1f) * 0.5f + 0.5f); + + if (u + v > 1.0f) { + u = 1.0f - u; + v = 1.0f - v; + } + float w = 1.0f - u - v; + + if (w > 1.0f) { + float diff = w - 1.0f; + w = 1.0f; + u += diff / 2.0f; + v += diff / 2.0f; + } else if (w < 0.0f) { + float diff = -w; + w = 0.0f; + u -= diff / 2.0f; + v -= diff / 2.0f; + } + + Vector3 P = triangle.m_vertex1 * u + triangle.m_vertex2 * v + triangle.m_vertex3 * w; + + std::vector dynData; + updateDynamicData(dynData, u, v, w, P, triangle); + + glBindVertexArray(VAO_dyn); + glBindBuffer(GL_ARRAY_BUFFER, VBO_dyn); + glBufferSubData(GL_ARRAY_BUFFER, 0, dynData.size() * sizeof(float), dynData.data()); + + // Draw lines + glDrawArrays(GL_LINES, 0, 6); + + // Draw text lines + int numTextVertices = (dynData.size() / 8) - 10; + if (numTextVertices > 0) { + glDrawArrays(GL_LINES, 10, numTextVertices); + } + + // Draw dots + glDrawArrays(GL_POINTS, 6, 4); + + glfwSwapBuffers(window); + glfwPollEvents(); + } + + glfwTerminate(); + return 0; +}