C++ Evas_GL_API类代码示例

// Initialize the shader and program object
static int
init_shaders(GLData *gld)
{
   Evas_GL_API *gl = gld->glapi;
   GLbyte vShaderStr[] =
      "attribute vec4 vPosition;    \n"
      "void main()                  \n"
      "{                            \n"
      "   gl_Position = vPosition;  \n"
      "}                            \n";

   GLbyte fShaderStr[] =
      "#ifdef GL_ES                                 \n"
      "precision mediump float;                     \n"
      "#endif                                       \n"
      "void main()                                  \n"
      "{                                            \n"
      "  gl_FragColor = vec4 ( 1.0, 0.0, 0.0, 1.0 );\n"
      "}                                            \n";

   GLint linked;

   // Load the vertex/fragment shaders
   gld->vtx_shader  = load_shader(gld, GL_VERTEX_SHADER, (const char*)vShaderStr);
   gld->fgmt_shader = load_shader(gld, GL_FRAGMENT_SHADER, (const char*)fShaderStr);

   // Create the program object
   gld->program = gl->glCreateProgram( );
   if (0 == gld->program)
     return 0;

   gl->glAttachShader(gld->program, gld->vtx_shader);
   gl->glAttachShader(gld->program, gld->fgmt_shader);

   gl->glBindAttribLocation(gld->program, 0, "vPosition");
   gl->glLinkProgram(gld->program);
   gl->glGetProgramiv(gld->program, GL_LINK_STATUS, &linked);

   if (!linked)
     {
        GLint info_len = 0;
        gl->glGetProgramiv(gld->program, GL_INFO_LOG_LENGTH, &info_len);
        if (1 < info_len)
          {
             char* info_log = malloc(sizeof(char) * info_len);

             gl->glGetProgramInfoLog(gld->program, info_len, NULL, info_log);
             _printf("Error linking program:\n%s\n", info_log);
             free(info_log);
             g_assert(FALSE);
          }
        gl->glDeleteProgram(gld->program);
        return 0;
     }
   return 1;
}

static void
_draw_gl(Evas_Object *obj)
{
   Evas_GL_API *gl = elm_glview_gl_api_get(obj);
   GLData *gld = evas_object_data_get(obj, "gld");
   if (!gld) return;

   render_gears(gld);
   gl->glFinish();
}

// resize callback gets called every time object is resized
static void
_resize_gl(Evas_Object *obj)
{
   int w, h;
   GLData *gld = evas_object_data_get(obj, "gld");
   Evas_GL_API *gl = gld->glapi;

   elm_glview_size_get(obj, &w, &h);

   // GL Viewport stuff. you can avoid doing this if viewport is all the
   // same as last frame if you want
   gl->glViewport(0, 0, w, h);
}

//--------------------------------//
static GLuint
load_shader( GLData *gld, GLenum type, const char *shader_src )
{
   Evas_GL_API *gl = gld->glapi;
   GLuint shader;
   GLint compiled;

   // Create the shader object
   shader = gl->glCreateShader(type);
   if (shader==0)
      return 0;

   // Load/Compile shader source
   gl->glShaderSource(shader, 1, &shader_src, NULL);
   gl->glCompileShader(shader);
   gl->glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);

   if (!compiled)
     {
        GLint info_len = 0;
        gl->glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &info_len);
        if (info_len > 1)
          {
             char* info_log = malloc(sizeof(char) * info_len);

             gl->glGetShaderInfoLog(shader, info_len, NULL, info_log);
             printf("Error compiling shader:\n%s\n======\n%s\n======\n", info_log, shader_src );
             free(info_log);
          }
        gl->glDeleteShader(shader);
        return 0;
     }

   return shader;
}

bool EwkView::createGLSurface()
{
    if (!m_isAccelerated)
        return true;

    static Evas_GL_Config evasGLConfig = {
        EVAS_GL_RGBA_8888,
        EVAS_GL_DEPTH_BIT_8,
        EVAS_GL_STENCIL_NONE,
        EVAS_GL_OPTIONS_NONE,
        EVAS_GL_MULTISAMPLE_NONE,
#if defined(EVAS_GL_API_VERSION) && EVAS_GL_API_VERSION >= 2
        EVAS_GL_GLES_2_X
#endif
    };

    // Recreate to current size: Replaces if non-null, and frees existing surface after (OwnPtr).
    if (deviceSize().width() && deviceSize().height()) {
        Evas_GL_Surface* surface = nullptr;
        surface = evas_gl_surface_create(m_evasGL, &evasGLConfig, deviceSize().width(), deviceSize().height());
        if (!surface)
            return false;

        m_evasGLSurface = std::make_unique<EvasGLSurface>(m_evasGL, surface);
    }

    if (!m_evasGLSurface)
        return false;

    Evas_Native_Surface nativeSurface;
    evas_gl_native_surface_get(m_evasGL, m_evasGLSurface->surface(), &nativeSurface);
    evas_object_image_native_surface_set(smartData()->image, &nativeSurface);

    evas_gl_make_current(m_evasGL, m_evasGLSurface->surface(), m_evasGLContext->context());

    Evas_GL_API* gl = evas_gl_api_get(m_evasGL);

    WKPoint boundsEnd = WKViewUserViewportToScene(wkView(), WKPointMake(deviceSize().width(), deviceSize().height()));
    gl->glViewport(0, 0, boundsEnd.x, boundsEnd.y);
    gl->glClearColor(1.0, 1.0, 1.0, 0);
    gl->glClear(GL_COLOR_BUFFER_BIT);

    return true;
}

// delete callback gets called when glview is deleted
static void
_del_gl(Evas_Object *obj)
{
   GLData *gld = evas_object_data_get(obj, "gld");
   if (!gld)
     {
        printf("Unable to get GLData. \n");
        g_assert(FALSE);
     }
   Evas_GL_API *gl = gld->glapi;

   gl->glDeleteShader(gld->vtx_shader);
   gl->glDeleteShader(gld->fgmt_shader);
   gl->glDeleteProgram(gld->program);
   gl->glDeleteBuffers(1, &gld->vbo);

   evas_object_data_del((Evas_Object*)obj, "..gld");
   free(gld);
}

// intialize callback that gets called once for intialization
static void
_init_gl(Evas_Object *obj)
{
   GLData *gld = evas_object_data_get(obj, "gld");
   Evas_GL_API *gl = gld->glapi;
   GLfloat vVertices[] = { 0.0f, 0.5f, 0.0f,
                          -0.5f, -0.5f, 0.0f,
                           0.5f, -0.5f, 0.0f };

   if (!init_shaders(gld))
     {
        _printf("Error Initializing Shaders\n");
        g_assert(FALSE);
     }

   gl->glGenBuffers(1, &gld->vbo);
   gl->glBindBuffer(GL_ARRAY_BUFFER, gld->vbo);
   gl->glBufferData(GL_ARRAY_BUFFER, 3 * 3 * 4, vVertices, GL_STATIC_DRAW);
}

/* new window size or exposure */
static void
gears_reshape(GLData *gld, int width, int height)
{
   Evas_GL_API *gl = gld->glapi;

   GLfloat ar, m[16] = {
      1.0, 0.0, 0.0, 0.0,
      0.0, 1.0, 0.0, 0.0,
      0.0, 0.0, 0.1, 0.0,
      0.0, 0.0, 0.0, 1.0
   };

   if (width < height)
     ar = width;
   else
     ar = height;

   m[0] = 0.1 * ar / width;
   m[5] = 0.1 * ar / height;
   memcpy(gld->proj, m, sizeof gld->proj);
   gl->glViewport(0, 0, (GLint) width, (GLint) height);
}

static void
gears_draw(GLData *gld)
{
   Evas_GL_API *gl = gld->glapi;

   static const GLfloat red[4] = { 0.8, 0.1, 0.0, 1.0 };
   static const GLfloat green[4] = { 0.0, 0.8, 0.2, 1.0 };
   static const GLfloat blue[4] = { 0.2, 0.2, 1.0, 1.0 };
   GLfloat m[16];

   gl->glClearColor(0.8, 0.8, 0.1, 0.5);
   gl->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

   memcpy(m, gld->proj, sizeof m);
   rotate(m, 2 * M_PI * gld->view_rotx / 360.0, 1, 0, 0);
   rotate(m, 2 * M_PI * gld->view_roty / 360.0, 0, 1, 0);
   rotate(m, 2 * M_PI * gld->view_rotz / 360.0, 0, 0, 1);

   draw_gear(gld, gld->gear1, m, -3.0, -2.0, gld->angle, red);
   draw_gear(gld, gld->gear2, m, 3.1, -2.0, -2 * gld->angle - 9.0, green);
   draw_gear(gld, gld->gear3, m, -3.1, 4.2, -2 * gld->angle - 25.0, blue);
}

static void
draw_gear(GLData *gld, Gear *gear, GLfloat *m,
          GLfloat x, GLfloat y, GLfloat angle, const GLfloat *color)
{
   Evas_GL_API *gl = gld->glapi;
   GLfloat tmp[16];

   memcpy(tmp, m, sizeof tmp);
   translate(tmp, x, y, 0);
   rotate(tmp, 2 * M_PI * angle / 360.0, 0, 0, 1);
   gl->glUniformMatrix4fv(gld->proj_location, 1, GL_FALSE, tmp);
   gl->glUniform3fv(gld->light_location, 1, gld->light);
   gl->glUniform4fv(gld->color_location, 1, color);

   gl->glBindBuffer(GL_ARRAY_BUFFER, gear->vbo);

   gl->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE,
                             6 * sizeof(GLfloat), NULL);
   gl->glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE,
                             6 * sizeof(GLfloat), (GLfloat *) 0 + 3);
   gl->glEnableVertexAttribArray(0);
   gl->glEnableVertexAttribArray(1);
   gl->glDrawArrays(GL_TRIANGLE_STRIP, 0, gear->count);
}

// draw callback is where all the main GL rendering happens
static void
_draw_gl(Evas_Object *obj)
{
   Evas_GL_API *gl = elm_glview_gl_api_get(obj);
   GLData *gld = evas_object_data_get(obj, "gld");

   if (!gld) return;
   int w, h;

   elm_glview_size_get(obj, &w, &h);

   gl->glViewport(0, 0, w, h);
   gl->glClearColor(red, 0.8, 0.3, 1);
   gl->glClear(GL_COLOR_BUFFER_BIT);

   // Draw a Triangle
   gl->glEnable(GL_BLEND);

   gl->glUseProgram(gld->program);

   gl->glBindBuffer(GL_ARRAY_BUFFER, gld->vbo);
   gl->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
   gl->glEnableVertexAttribArray(0);

   gl->glDrawArrays(GL_TRIANGLES, 0, 3);

   // Optional - Flush the GL pipeline
   gl->glFinish();

   red -= 0.1;
   if (0.0 > red) red = 1.0;
}

/*  Draw a gear wheel.  You'll probably want to call this function when
 *  building a display list since we do a lot of trig here.
 *
 *  Input:  inner_radius - radius of hole at center
 *          outer_radius - radius at center of teeth
 *          width - width of gear
 *          teeth - number of teeth
 *          tooth_depth - depth of tooth
 */
static Gear *
make_gear(GLData *gld, GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
          GLint teeth, GLfloat tooth_depth)
{
   GLint i;
   GLfloat r0, r1, r2;
   GLfloat da;
   GLfloat *v;
   Gear *gear;
   double s[5], c[5];
   GLfloat normal[3];
   const int tris_per_tooth = 20;
   Evas_GL_API *gl = gld->glapi;

   gear = (Gear*)malloc(sizeof(Gear));
   if (gear == NULL)
     return NULL;

   r0 = inner_radius;
   r1 = outer_radius - tooth_depth / 2.0;
   r2 = outer_radius + tooth_depth / 2.0;

   da = 2.0 * M_PI / teeth / 4.0;

   gear->vertices = calloc(teeth * tris_per_tooth * 3 * 6,
                           sizeof *gear->vertices);
   s[4] = 0;
   c[4] = 1;
   v = gear->vertices;
   for (i = 0; i < teeth; i++)
     {
        s[0] = s[4];
        c[0] = c[4];
        s[1] = sin(i * 2.0 * M_PI / teeth + da);
        c[1] = cos(i * 2.0 * M_PI / teeth + da);
        s[2] = sin(i * 2.0 * M_PI / teeth + da * 2);
        c[2] = cos(i * 2.0 * M_PI / teeth + da * 2);
        s[3] = sin(i * 2.0 * M_PI / teeth + da * 3);
        c[3] = cos(i * 2.0 * M_PI / teeth + da * 3);
        s[4] = sin(i * 2.0 * M_PI / teeth + da * 4);
        c[4] = cos(i * 2.0 * M_PI / teeth + da * 4);

        normal[0] = 0.0;
        normal[1] = 0.0;
        normal[2] = 1.0;

        v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal);

        v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal);
        v = vert(v, r2 * c[2], r2 * s[2], width * 0.5, normal);
        v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal);
        v = vert(v, r1 * c[3], r1 * s[3], width * 0.5, normal);
        v = vert(v, r0 * c[0], r0 * s[0], width * 0.5, normal);
        v = vert(v, r1 * c[4], r1 * s[4], width * 0.5, normal);
        v = vert(v, r0 * c[4], r0 * s[4], width * 0.5, normal);

        v = vert(v, r0 * c[4], r0 * s[4], width * 0.5, normal);
        v = vert(v, r0 * c[0], r0 * s[0], width * 0.5, normal);
        v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal);
        v = vert(v, r0 * c[0], r0 * s[0], -width * 0.5, normal);

        normal[0] = 0.0;
        normal[1] = 0.0;
        normal[2] = -1.0;

        v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal);

        v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal);
        v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal);
        v = vert(v, r0 * c[0], r0 * s[0], -width * 0.5, normal);
        v = vert(v, r1 * c[3], r1 * s[3], -width * 0.5, normal);
        v = vert(v, r1 * c[0], r1 * s[0], -width * 0.5, normal);
        v = vert(v, r2 * c[2], r2 * s[2], -width * 0.5, normal);
        v = vert(v, r2 * c[1], r2 * s[1], -width * 0.5, normal);

        v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal);

        v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal);
        v = vert(v, r1 * c[0], r1 * s[0], -width * 0.5, normal);
        v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal);
        v = vert(v, r2 * c[1], r2 * s[1], -width * 0.5, normal);
        v = vert(v, r2 * c[2], r2 * s[2], width * 0.5, normal);
        v = vert(v, r2 * c[2], r2 * s[2], -width * 0.5, normal);
        v = vert(v, r1 * c[3], r1 * s[3], width * 0.5, normal);
        v = vert(v, r1 * c[3], r1 * s[3], -width * 0.5, normal);
        v = vert(v, r1 * c[4], r1 * s[4], width * 0.5, normal);
        v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal);

        v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal);
     }

//.........这里部分代码省略.........

static void
gears_init(GLData *gld)
{
   Evas_GL_API *gl = gld->glapi;

   const char *p;
   char msg[512];

   gl->glEnable(GL_CULL_FACE);
   gl->glEnable(GL_DEPTH_TEST);

   p = vertex_shader;
   gld->vtx_shader = gl->glCreateShader(GL_VERTEX_SHADER);
   gl->glShaderSource(gld->vtx_shader, 1, &p, NULL);
   gl->glCompileShader(gld->vtx_shader);
   gl->glGetShaderInfoLog(gld->vtx_shader, sizeof msg, NULL, msg);
   printf("vertex shader info: %s\n", msg);

   p = fragment_shader;
   gld->fgmt_shader = gl->glCreateShader(GL_FRAGMENT_SHADER);
   gl->glShaderSource(gld->fgmt_shader, 1, &p, NULL);
   gl->glCompileShader(gld->fgmt_shader);
   gl->glGetShaderInfoLog(gld->fgmt_shader, sizeof msg, NULL, msg);
   printf("fragment shader info: %s\n", msg);

   gld->program = gl->glCreateProgram();
   gl->glAttachShader(gld->program, gld->vtx_shader);
   gl->glAttachShader(gld->program, gld->fgmt_shader);
   gl->glBindAttribLocation(gld->program, 0, "position");
   gl->glBindAttribLocation(gld->program, 1, "normal");

   gl->glLinkProgram(gld->program);
   gl->glGetProgramInfoLog(gld->program, sizeof msg, NULL, msg);
   printf("info: %s\n", msg);

   gl->glUseProgram(gld->program);
   gld->proj_location  = gl->glGetUniformLocation(gld->program, "proj");
   gld->light_location = gl->glGetUniformLocation(gld->program, "light");
   gld->color_location = gl->glGetUniformLocation(gld->program, "color");

   /* make the gears */
   gld->gear1 = make_gear(gld, 1.0, 4.0, 1.0, 20, 0.7);
   gld->gear2 = make_gear(gld, 0.5, 2.0, 2.0, 10, 0.7);
   gld->gear3 = make_gear(gld, 1.3, 2.0, 0.5, 10, 0.7);
}