I would like to develop OpenGL ES 2.0 apps on my Ubuntu machine. I could not find any libraries/emulators that support GLES 2.0 yet. Any suggestions?
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问题:
回答1:
You can use POWERVR SDK to emulate Opengl es on your PC. You can download the SDK here. The archive provides the necessary steps to install the emulation libraries as a documentation file and includes tutorials and demo applications with source codes.
回答2:
GLFW, Mesa, Ubuntu 16.04 AMD64
This was not easy to setup on Ubuntu 14.04, but now it just works.
sudo apt-get install libglfw3-dev libgles2-mesa-dev gcc glfw_triangle.c -lGLESv2 -lglfw Output:
Source:
#include #include #define GLFW_INCLUDE_ES2 #include 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_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 #if defined(GLFW_INCLUDE_GLEXT) #include #endif This source seems to be written 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.
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.
回答3:
Mesa supports it. If you want to restrict yourself to OpenGL ES only then you'll need to build it into a separate directory and then add the appropriate include and library directories.
回答4:
Develop to the OpenGL 2.0 standard, and don't use immediate mode or fixed function mode. Essentially your program will be ES 2.0 compliant.
回答5:
you can generate a header that has only those functions that you really need. And with glfw you can create an opengl es context. So you can't accidently use functions that you do not want to use, because they won't be defined in this way. I found this that might help you here.