I initialize the framebuffer

glGenFramebuffersEXT(1, &fbo); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo); glEnable(GL_TEXTURE_2D); glGenTextures(1, &fbo_texture); glBindTexture(GL_TEXTURE_2D, fbo_texture); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fbo_texture, 0); GLenum status; if ((status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT)) != GL_FRAMEBUFFER_COMPLETE_EXT) { fprintf(stderr, "glCheckFramebufferStatus: error %p", status); } glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

Then in the cycle I render the scene into a texture, process it with a shader and display it on the screen. On my PC everything is OK. (Radeon HD 7870.) On another PC (GeForce FX 5200), at launch, the glCheckFramebufferStatusEXT function generates an error code 8cdd and 8cdd black window with a frame rate of 0-1 fps.

Error led here: https://www.khronos.org/opengles/sdk...fferStatus.xml

0x8CDD (GL_FRAMEBUFFER_UNSUPPORTED_EXT)
The set of restrictions.

Full source code:

 #include "main.hpp" GLuint fbo, fbo_texture, rbo_depth; GLuint vbo_fbo_vertices; GLuint program_postproc, attribute_v_coord_postproc, uniform_fbo_texture; GLuint vs, fs; Shader shader; int main(void) { init(); glGenFramebuffersEXT(1, &fbo); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo); glEnable(GL_TEXTURE_2D); glGenTextures(1, &fbo_texture); glBindTexture(GL_TEXTURE_2D, fbo_texture); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fbo_texture, 0); GLenum status; if ((status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT)) != GL_FRAMEBUFFER_COMPLETE_EXT) { fprintf(stderr, "glCheckFramebufferStatus: error %p", status); } glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); GLfloat fbo_vertices[] = { -1, -1, 1, -1,-1, 1, 1, 1 }; glGenBuffers(1, &vbo_fbo_vertices); glBindBuffer(GL_ARRAY_BUFFER, vbo_fbo_vertices); glBufferData(GL_ARRAY_BUFFER, sizeof(fbo_vertices), fbo_vertices, GL_STATIC_DRAW); glBindBuffer(GL_ARRAY_BUFFER, 0); shader.load("shaders/post_processing.vert", "shaders/post_processing.frag"); attribute_v_coord_postproc = glGetAttribLocation(shader.program(), "v_coord"); if (attribute_v_coord_postproc == -1) { fprintf(stderr, "Could not bind attribute %s\n", "v_coord"); return 0; } uniform_fbo_texture = glGetUniformLocation(shader.program(), "fbo_texture"); if (uniform_fbo_texture == -1) { fprintf(stderr, "Could not bind uniform %s\n", "fbo_texture"); return 0; } while (!glfwWindowShouldClose(m_window)) { glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo); glClear(GL_COLOR_BUFFER_BIT); glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); glClear(GL_COLOR_BUFFER_BIT); shader.use(); glBindTexture(GL_TEXTURE_2D, fbo_texture); glUniform1i(uniform_fbo_texture, /*GL_TEXTURE*/0); glEnableVertexAttribArray(attribute_v_coord_postproc); glBindBuffer(GL_ARRAY_BUFFER, vbo_fbo_vertices); glVertexAttribPointer(attribute_v_coord_postproc, 2, GL_FLOAT, GL_FALSE, 0, 0); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glDisableVertexAttribArray(attribute_v_coord_postproc); glfwSwapBuffers(m_window); glfwPollEvents(); } glDeleteRenderbuffersEXT(1, &rbo_depth); glDeleteTextures(1, &fbo_texture); glDeleteFramebuffersEXT(1, &fbo); glDeleteBuffers(1, &vbo_fbo_vertices); glDeleteProgram(shader.program()); glfwDestroyWindow(m_window); glfwTerminate(); exit(EXIT_SUCCESS); } void callbackError(int error, const char* description) { fputs(description, stderr); } void callbackKey(GLFWwindow* window, int key, int scancode, int action, int mods) { if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS) glfwSetWindowShouldClose(window, GL_TRUE); } void callbackFramebufferSize(GLFWwindow* window, int width, int height) { m_width = width; m_height = height; glBindTexture(GL_TEXTURE_2D, fbo_texture); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0); glBindTexture(GL_TEXTURE_2D, 0); } void init() { glfwSetErrorCallback(callbackError); if (!glfwInit()) exit(EXIT_FAILURE); m_width = 800; m_height = 600; m_window = glfwCreateWindow(m_width, m_height, "Framebuffer Test", NULL, NULL); if (!m_window) { glfwTerminate(); exit(EXIT_FAILURE); } glfwMakeContextCurrent(m_window); glfwSwapInterval(0); glfwSetKeyCallback(m_window, callbackKey); glfwSetFramebufferSizeCallback(m_window, callbackFramebufferSize); glewExperimental = GL_TRUE; if (glewInit() != GLEW_OK) std::cout << "GLEW Init Error" << std::endl; glClearColor(0.2, 0.3, 0.4, 1.0); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); }

Vertex shader:

 attribute vec2 v_coord; uniform sampler2D fbo_texture; varying vec2 f_texcoord; void main(void) { gl_Position = vec4(v_coord, 0.0, 1.0); f_texcoord = (v_coord + 1.0) / 2.0; }

Fragment shader:

 uniform sampler2D fbo_texture; varying vec2 f_texcoord; void main(void) { gl_FragColor = texture2D(fbo_texture, f_texcoord); if (f_texcoord.x < 0.2) gl_FragColor *= vec4(1.0, 2.0, 1.0, 1.0); else if (f_texcoord.x > 0.8) gl_FragColor *= vec4(1.0, 2.0, 2.0, 1.0); else gl_FragColor *= vec4(2.0, 1.0, 2.0, 1.0); }

Screenshots:

GeForce FX 5200. OpenGL 2.0 Radeon HD 7870. OpenGL 2.1 (VirtualBox)

    1 answer 1

    In my case, to solve such problems, the replacement of all ***EXT functions and constants with their usual analogs, without ***EXT , helped.

     glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); glEnable(GL_TEXTURE_2D); glGenTextures(1, &fbo_texture); glBindTexture(GL_TEXTURE_2D, fbo_texture); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, fbo_texture, 0); glBindFramebuffer(GL_FRAMEBUFFER, 0);