1. rcrnstn/sdf-winding
  2. Commit f5bcb07024cb0d203358a718c9c7af44687e7bfc
Browse code

Add OpenGL boilerplate

Robert Cranston authored on 08/03/2026 00:46:06
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.gitignore
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+/sdf-winding
Makefile
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+CXXFLAGS += -std=c++11
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+CXXFLAGS += -Wall -Wextra -Wpedantic
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+CXXFLAGS += -Og -g -fsanitize=undefined,address
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+LDLIBS   += -lGL -lGLEW -lglfw
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+
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+sdf-winding:
README.md
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 I have not read a single word of that reference manual, proceed accordingly.
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+To build, run `make`. You need the following dependencies on your system:
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+
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+-   OpenGL
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+-   [GLEW][]
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+-   [GLFW][]
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+
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 [`sdf-winding`]:  https://git.rcrnstn.net/rcrnstn/sdf-winding
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 [glyph]:          https://en.wikipedia.org/wiki/Glyph
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 [winding number]: https://en.wikipedia.org/wiki/Winding_number
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 [SDF]:            https://en.wikipedia.org/wiki/Signed_distance_function
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 [Figure 7]:       https://developer.apple.com/fonts/TrueType-Reference-Manual/RM02/FE6.gif
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 [TrueType]:       https://developer.apple.com/fonts/TrueType-Reference-Manual/RM02/Chap2.html#distinguishing
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+[GLEW]:           https://glew.sourceforge.net
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+[GLFW]:           https://www.glfw.org
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 ## License
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sdf-winding.cpp
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+#include <iostream>
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+
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+#include <GL/glew.h>
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+#include <GLFW/glfw3.h>
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+
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+constexpr auto width  = 640;
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+constexpr auto height = 480;
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+constexpr auto title  = "sdf-winding";
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+
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+static void APIENTRY debug_message_callback(
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+    GLenum          /* source   */,
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+    GLenum          /* type     */,
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+    GLuint          /* id       */,
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+    GLenum          /* severity */,
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+    GLsizei         /* length   */,
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+    GLchar  const *    message,
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+    void    const * /* param    */
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+)
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+{
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+    std::cerr << message << std::endl;
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+};
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+
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+int main()
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+{
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+    /// Window/context
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+    glfwInit();
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+    auto window = glfwCreateWindow(width, height, title, nullptr, nullptr);
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+    glfwMakeContextCurrent(window);
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+    glewInit();
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+
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+    /// Debug
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+    glEnable(GL_DEBUG_OUTPUT);
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+    glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
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+    glDebugMessageCallback(debug_message_callback, nullptr);
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+
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+    /// Shader
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+    auto make_program = [](char const * fragment_source)
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+    {
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+        auto program = glCreateProgram();
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+        auto attach  = [&](GLenum type, char const * source)
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+        {
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+            auto shader = glCreateShader(type);
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+            glShaderSource(shader, 1, &source, nullptr);
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+            glCompileShader(shader);
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+            glAttachShader(program, shader);
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+        };
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+        attach(GL_VERTEX_SHADER, R"(
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+            #version 140
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+
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+            out vec2 tex_coord;
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+
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+            void main()
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+            {
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+                tex_coord = vec2[](
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+                    vec2(0, 0),
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+                    vec2(2, 0),
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+                    vec2(0, 2)
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+                )[gl_VertexID];
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+                gl_Position = vec4(tex_coord*2-1, 0, 1);
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+            }
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+        )");
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+        attach(GL_FRAGMENT_SHADER, fragment_source);
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+        glLinkProgram(program);
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+        return program;
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+    };
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+    auto tex_coord_program = make_program(R"(
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+        #version 140
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+
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+        in vec2 tex_coord;
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+
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+        void main()
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+        {
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+            gl_FragColor = vec4(tex_coord, 0, 1);
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+        }
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+    )");
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+
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+    /// Draw loop
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+    while (glfwPollEvents(), !glfwWindowShouldClose(window))
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+    {
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+        //// Input
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+        if (glfwGetKey(window, GLFW_KEY_Q))
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+            glfwSetWindowShouldClose(window, GLFW_TRUE);
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+
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+        //// Draw
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+        glClear(GL_COLOR_BUFFER_BIT);
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+        glUseProgram(tex_coord_program);
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+        glDrawArrays(GL_TRIANGLES, 0, 3);
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+
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+        //// Swap
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+        glfwSwapBuffers(window);
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+    }
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+
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+    /// Cleanup
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+    glfwDestroyWindow(window);
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+    glfwTerminate();
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+}