Any GLES examples, in C++, on x86 Linux?

Mesa demos!

• http://cgit.freedesktop.org/mesa/demos
• http://cgit.freedesktop.org/mesa/demos/tree/src/egl/opengles2
• http://cgit.freedesktop.org/mesa/demos/tree/src/egl/opengles2/es2tri.c

GLFW, Mesa, Ubuntu 16.04 AMD64

I'm not sure if GLUT supports GLES, but GLFW does, greatly simplifying window management.

sudo apt-get install libglfw3-dev libgles2-mesa-devgcc glfw_triangle.c -lGLESv2 -lglfw

Output:

Source:

#include <stdio.h>#include <stdlib.h>#define GLFW_INCLUDE_ES2#include <GLFW/glfw3.h>static const GLuint WIDTH = 800;static const GLuint HEIGHT = 600;static const GLchar* vertex_shader_source =    "#version 100\n"    "attribute vec3 position;\n"    "void main() {\n"    "   gl_Position = vec4(position, 1.0);\n"    "}\n";static const GLchar* fragment_shader_source =    "#version 100\n"    "void main() {\n"    "   gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n"    "}\n";static const GLfloat vertices[] = {        0.0f,  0.5f, 0.0f,        0.5f, -0.5f, 0.0f,    -0.5f, -0.5f, 0.0f,};GLint common_get_shader_program(const char *vertex_shader_source, const char *fragment_shader_source) {    enum Consts {INFOLOG_LEN = 512};    GLchar infoLog[INFOLOG_LEN];    GLint fragment_shader;    GLint shader_program;    GLint success;    GLint vertex_shader;    /* Vertex shader */    vertex_shader = glCreateShader(GL_VERTEX_SHADER);    glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);    glCompileShader(vertex_shader);    glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);    if (!success) {        glGetShaderInfoLog(vertex_shader, INFOLOG_LEN, NULL, infoLog);        printf("ERROR::SHADER::VERTEX::COMPILATION_FAILED\n%s\n", infoLog);    }    /* Fragment shader */    fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);    glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);    glCompileShader(fragment_shader);    glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);    if (!success) {        glGetShaderInfoLog(fragment_shader, INFOLOG_LEN, NULL, infoLog);        printf("ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n%s\n", infoLog);    }    /* Link shaders */    shader_program = glCreateProgram();    glAttachShader(shader_program, vertex_shader);    glAttachShader(shader_program, fragment_shader);    glLinkProgram(shader_program);    glGetProgramiv(shader_program, GL_LINK_STATUS, &success);    if (!success) {        glGetProgramInfoLog(shader_program, INFOLOG_LEN, NULL, infoLog);        printf("ERROR::SHADER::PROGRAM::LINKING_FAILED\n%s\n", infoLog);    }    glDeleteShader(vertex_shader);    glDeleteShader(fragment_shader);    return shader_program;}int main(void) {    GLuint shader_program, vbo;    GLint pos;    GLFWwindow* window;    glfwInit();    glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);    window = glfwCreateWindow(WIDTH, HEIGHT, __FILE__, NULL, NULL);    glfwMakeContextCurrent(window);    printf("GL_VERSION  : %s\n", glGetString(GL_VERSION) );    printf("GL_RENDERER : %s\n", glGetString(GL_RENDERER) );    shader_program = common_get_shader_program(vertex_shader_source, fragment_shader_source);    pos = glGetAttribLocation(shader_program, "position");    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);    glViewport(0, 0, WIDTH, HEIGHT);    glGenBuffers(1, &vbo);    glBindBuffer(GL_ARRAY_BUFFER, vbo);    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);    glVertexAttribPointer(pos, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid*)0);    glEnableVertexAttribArray(pos);    glBindBuffer(GL_ARRAY_BUFFER, 0);    while (!glfwWindowShouldClose(window)) {        glfwPollEvents();        glClear(GL_COLOR_BUFFER_BIT);        glUseProgram(shader_program);        glDrawArrays(GL_TRIANGLES, 0, 3);        glfwSwapBuffers(window);    }    glDeleteBuffers(1, &vbo);    glfwTerminate();    return EXIT_SUCCESS;}

The key line lines of code are:

#define GLFW_INCLUDE_ES2#include <GLFW/glfw3.h>

GLFW_INCLUDE_ES2 is documented at: http://www.glfw.org/docs/latest/build_guide.html#build_macros and a quick look at the source shows that it forwards to GLES:

 #elif defined(GLFW_INCLUDE_ES2)  #include <GLES2/gl2.h>  #if defined(GLFW_INCLUDE_GLEXT)   #include <GLES2/gl2ext.h>  #endif

This source seems to be is in the common subset of GLES and OpenGL (like much of GLES), and also compiles with -lGL if we remove the #define GLFW_INCLUDE_ES2.

If we add things which are not in GLES like immediate rendering glBegin, link fails as expected.

See also: How to develop OpenGL ES (GLES) 2.0 applications on Linux?

Credits: genpfult made the code much more correct.

ARM Mali OpenGL ES SDK

• download from: http://malideveloper.arm.com/resources/sdks/opengl-es-sdk-for-linux/
• open the documentation HTML on a browser
• follow the "Quick Start Guide", it's simple

Contains several interesting open source examples + windowing system boilerplate (X11 + EGL).

The build system supports easy cross compilation for ARM / Mali SoCs, but I haven't tested that yet.

The key component included seems to be the "OpenGL ES Emulator" http://malideveloper.arm.com/resources/tools/opengl-es-emulator/ which "maps OpenGL ES 3.2 API calls to the OpenGL API". But that does not ship with source, only precompiled.

Uses a custom enterprisey EULA that appears to be permissive, but yeah, ask your lawyer.

Tested on SDK v2.4.4.