手機 - Motorola XT897 - Sailfish OS 4.4.0.68 - Wayland (OpenGL ES 2.0) - Use Shader

參考資訊：
https://jan.newmarch.name/Wayland/index.html
https://wayland.freedesktop.org/docs/html/apa.html
https://bugaevc.gitbooks.io/writing-wayland-clients/content/
https://gist.github.com/Miouyouyou/ca15af1c7f2696f66b0e013058f110b4

main.c

#include <string.h>
#include <stdlib.h>
#include <unistd.h>
 
#include <wayland-server.h>
#include <wayland-client.h>
#include <wayland-client-protocol.h>
#include <wayland-egl.h>
 
#include <EGL/egl.h>
#include <EGL/eglplatform.h>
#include <GLES2/gl2.h>
 
#define LCD_W   540
#define LCD_H   960
 
struct wl_shell *wl_shell = NULL;
struct wl_region *wl_region = NULL;
struct wl_display *wl_display = NULL;
struct wl_surface *wl_surface = NULL;
struct wl_registry *wl_registry = NULL;
struct wl_egl_window *wl_egl_window = NULL;
struct wl_compositor *wl_compositor = NULL;
struct wl_shell_surface *wl_shell_surface = NULL;

const char *vShaderSrc = 
    "attribute vec4 vPosition;    \n"
    "void main(void)              \n"
    "{                            \n"
    "    gl_Position = vPosition; \n"
    "}";
 
const char *fShaderSrc =
    "#ifdef GL_ES               \n"
    "precision mediump float;   \n"
    "#endif                     \n"
    "uniform vec4 vColor;       \n"
    "void main(void)            \n"
    "{                          \n"
    "    gl_FragColor = vColor; \n"
    "}";
 
static void global_registry_handler(void *data, struct wl_registry *registry, uint32_t id, const char *interface, uint32_t version)
{
    if (strcmp(interface, "wl_compositor") == 0) {
        wl_compositor = wl_registry_bind(registry, id, &wl_compositor_interface, 1);
    }
    else if (strcmp(interface, "wl_shell") == 0) {
        wl_shell = wl_registry_bind(registry, id, &wl_shell_interface, 1);
    }
}
 
static void global_registry_remover(void *data, struct wl_registry *registry, uint32_t id)
{
}
 
const struct wl_registry_listener listener = {
    global_registry_handler,
    global_registry_remover
};
 
int main(int argc, char **argv)
{
    wl_display = wl_display_connect(NULL);
    wl_registry = wl_display_get_registry(wl_display);
    wl_registry_add_listener(wl_registry, &listener, NULL);
    wl_display_dispatch(wl_display);
    wl_display_roundtrip(wl_display);
    wl_surface = wl_compositor_create_surface(wl_compositor);
    wl_shell_surface = wl_shell_get_shell_surface(wl_shell, wl_surface);
    wl_shell_surface_set_toplevel(wl_shell_surface);
    wl_region = wl_compositor_create_region(wl_compositor);
    wl_region_add(wl_region, 0, 0, LCD_W, LCD_H);
    wl_surface_set_opaque_region(wl_surface, wl_region);
    wl_egl_window = wl_egl_window_create(wl_surface, LCD_W, LCD_H);
 
    EGLContext egl_context;
    EGLSurface egl_surface;
    EGLint egl_numConfigs;
    EGLint egl_majorVersion;
    EGLint egl_minorVersion;
    EGLConfig egl_config;
    EGLint egl_attribs[] = {
        EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
        EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
        EGL_RED_SIZE, 8,
        EGL_GREEN_SIZE, 8,
        EGL_BLUE_SIZE, 8,
        EGL_NONE
    };
    EGLint egl_context_attribs[] = {
        EGL_CONTEXT_CLIENT_VERSION, 2,
        EGL_NONE, EGL_NONE
    };
    EGLDisplay egl_display = eglGetDisplay(wl_display);
    eglInitialize(egl_display, &egl_majorVersion, &egl_minorVersion);
    eglGetConfigs(egl_display, NULL, 0, &egl_numConfigs);
    eglChooseConfig(egl_display, egl_attribs, &egl_config, 1, &egl_numConfigs);
    egl_surface = eglCreateWindowSurface(egl_display, egl_config, wl_egl_window, NULL);
    egl_context = eglCreateContext(egl_display, egl_config, EGL_NO_CONTEXT, egl_context_attribs);
    eglMakeCurrent(egl_display, egl_surface, egl_surface, egl_context);
 
    wl_display_dispatch_pending(wl_display);
    glViewport(0, 0, LCD_W, LCD_H);
    glClearColor(0.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);

    GLuint vShader = 0;
    GLuint fShader = 0;
    GLuint pObject = 0;
  
    vShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vShader, 1, &vShaderSrc, NULL);
    glCompileShader(vShader);
  
    fShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fShader, 1, &fShaderSrc, NULL);
    glCompileShader(fShader);
  
    pObject = glCreateProgram();
    glAttachShader(pObject, vShader);
    glAttachShader(pObject, fShader);
    glLinkProgram(pObject);
    glUseProgram(pObject);
      
    GLfloat v[] = {
         0.0f,  0.5f, 0.0f,
        -0.5f, -0.5f, 0.0f,
         0.5f, -0.5f, 0.0f
    };
 
    GLuint vp = glGetAttribLocation(pObject, "vPosition");
    glVertexAttribPointer(vp, 3, GL_FLOAT, GL_FALSE, 0, v);
    glEnableVertexAttribArray(vp);
 
    GLuint vc = glGetUniformLocation(pObject, "vColor");
    glUniform4f(vc, 1.0f, 0.0f, 0.0f, 1.0f);
 
    glViewport(0, 0, LCD_W, LCD_H);
    glClear(GL_COLOR_BUFFER_BIT);
    glDrawArrays(GL_TRIANGLES, 0, 3);

    eglSwapBuffers(egl_display, egl_surface);
    usleep(3000000);
 
    eglDestroySurface(egl_display, egl_surface);
    eglDestroyContext(egl_display, egl_context);
    wl_egl_window_destroy(wl_egl_window);
    eglTerminate(egl_display);
  
    wl_region_destroy(wl_region);
    wl_shell_surface_destroy(wl_shell_surface);
    wl_shell_destroy(wl_shell);
    wl_surface_destroy(wl_surface);
    wl_compositor_destroy(wl_compositor);
    wl_registry_destroy(wl_registry);
    wl_display_disconnect(wl_display);
    return 0;
}

編譯、執行

$ gcc main.c -o main -lwayland-client -lwayland-egl -lEGL -lGLESv2
$ ./main