ousttrue · June 3, 2019 13:39 · Jun 3, 2019
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -0,0 +1,23 @@
+CMAKE_MINIMUM_REQUIRED(VERSION 3.0.0)
+PROJECT(em_gl VERSION 0.1.0)
+
+LINK_DIRECTORIES(
+    $ENV{VCPKG_ROOT}/installed/x64-windows/lib
+    )
+
+FILE(GLOB SRC
+    *.cpp
+    *.h
+    ) 
+
+ADD_EXECUTABLE(${PROJECT_NAME} ${SRC})
+
+TARGET_INCLUDE_DIRECTORIES(${PROJECT_NAME} PUBLIC
+    $ENV{VCPKG_ROOT}/installed/x64-windows/include
+    ${CMAKE_CURRENT_LIST_DIR}/../emsdk/fastcomp/emscripten/system/include
+    )
+
+TARGET_LINK_LIBRARIES(${PROJECT_NAME}
+    glad
+    glfw3dll
+    )
diff --git a/main.cpp b/main.cpp
@@ -0,0 +1,158 @@
+// emcc main.cpp -o index.html -s USE_WEBGL2=1 -s USE_GLFW=3 -s WASM=1 -std=c++1z
+
+// base:  https://www.glfw.org/docs/latest/quick.html#quick_example
+// ref: https://gist.github.com/SuperV1234/5c5ad838fe5fe1bf54f9
+
+#include <functional>
+#include <vector>
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#define GL_GLEXT_PROTOTYPES
+#define EGL_EGLEXT_PROTOTYPES
+#else
+#include <glad/glad.h>
+#endif
+#include <GLFW/glfw3.h>
+#include "linmath.h"
+#include <stdlib.h>
+#include <stdio.h>
+static const struct
+{
+    float x, y;
+    float r, g, b;
+} vertices[3] =
+    {
+        {-0.6f, -0.4f, 1.f, 0.f, 0.f},
+        {0.6f, -0.4f, 0.f, 1.f, 0.f},
+        {0.f, 0.6f, 0.f, 0.f, 1.f}};
+
+static const char *vertex_shader_text =
+    "uniform mat4 MVP;\n"
+    "attribute vec3 vCol;\n"
+    "attribute vec2 vPos;\n"
+    "varying vec3 color;\n"
+    "void main()\n"
+    "{\n"
+    "    gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
+    "    color = vCol;\n"
+    "}\n";
+
+static const char *fragment_shader_text =
+    "precision mediump float;\n"
+    "varying vec3 color;\n"
+    "void main()\n"
+    "{\n"
+    "    gl_FragColor = vec4(color, 1.0);\n"
+    "}\n";
+
+static void error_callback(int error, const char *description)
+{
+    fprintf(stderr, "Error: %s\n", description);
+}
+static void key_callback(GLFWwindow *window, int key, int scancode, int action, int mods)
+{
+    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+        glfwSetWindowShouldClose(window, GLFW_TRUE);
+}
+
+std::function<void()> loop;
+void main_loop() { loop(); }
+
+void check_error(GLuint shader)
+{
+    GLint result;
+    glGetShaderiv(shader, GL_COMPILE_STATUS, &result);
+    if (result == GL_FALSE)
+    {
+        GLint log_length;
+        glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &log_length);
+        std::vector<GLchar> log(log_length);
+
+        GLsizei length;
+        glGetShaderInfoLog(shader, log.size(), &length, log.data());
+
+        error_callback(0, log.data());
+    }
+}
+
+int main(void)
+{
+    GLint mvp_location, vpos_location, vcol_location;
+    glfwSetErrorCallback(error_callback);
+    if (!glfwInit())
+        exit(EXIT_FAILURE);
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
+    auto window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
+    if (!window)
+    {
+        glfwTerminate();
+        exit(EXIT_FAILURE);
+    }
+    glfwSetKeyCallback(window, key_callback);
+    glfwMakeContextCurrent(window);
+#ifdef __EMSCRIPTEN__
+#else
+    gladLoadGL();
+#endif
+    glfwSwapInterval(1);
+    // NOTE: OpenGL error checks have been omitted for brevity
+    GLuint vertex_buffer;
+    glGenBuffers(1, &vertex_buffer);
+    glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+    auto vertex_shader = glCreateShader(GL_VERTEX_SHADER);
+    glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
+    glCompileShader(vertex_shader);
+    check_error(vertex_shader);
+
+    auto fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
+    glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
+    glCompileShader(fragment_shader);
+    check_error(fragment_shader);
+
+    auto program = glCreateProgram();
+    glAttachShader(program, vertex_shader);
+    glAttachShader(program, fragment_shader);
+    glLinkProgram(program);
+    mvp_location = glGetUniformLocation(program, "MVP");
+    vpos_location = glGetAttribLocation(program, "vPos");
+    vcol_location = glGetAttribLocation(program, "vCol");
+    glEnableVertexAttribArray(vpos_location);
+    glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
+                          sizeof(vertices[0]), (void *)0);
+    glEnableVertexAttribArray(vcol_location);
+    glVertexAttribPointer(vcol_location, 3, GL_FLOAT, GL_FALSE,
+                          sizeof(vertices[0]), (void *)(sizeof(float) * 2));
+
+    loop = [&] {
+        float ratio;
+        int width, height;
+        mat4x4 m, p, mvp;
+        glfwGetFramebufferSize(window, &width, &height);
+        ratio = width / (float)height;
+        glViewport(0, 0, width, height);
+        glClear(GL_COLOR_BUFFER_BIT);
+        mat4x4_identity(m);
+        mat4x4_rotate_Z(m, m, (float)glfwGetTime());
+        mat4x4_ortho(p, -ratio, ratio, -1.f, 1.f, 1.f, -1.f);
+        mat4x4_mul(mvp, p, m);
+        glUseProgram(program);
+        glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat *)mvp);
+        glDrawArrays(GL_TRIANGLES, 0, 3);
+        glfwSwapBuffers(window);
+        glfwPollEvents();
+    };
+
+#ifdef __EMSCRIPTEN__
+    emscripten_set_main_loop(main_loop, 0, true);
+#else
+    while (!glfwWindowShouldClose(window))
+        main_loop();
+#endif
+
+    glfwDestroyWindow(window);
+    glfwTerminate();
+    exit(EXIT_SUCCESS);
+}