glDrawArray doesn't draw anything when using secondary thread + glMapBuffer(thread receive pointer and use it as a buffer) to update data in VBO. Example code:
#include <thread>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
const char vsource [] = "#version 330 core\nin vec3 position;\nvoid main(void){gl_Position = vec4(position,1.0f);}\0";
const char fsource [] = "#version 330 core\nvoid main(void){gl_FragColor = vec4(1.0f,0.0f,0.0f,1.0f);}\0";
bool ext = 0;
void gen_function(float *data, unsigned count)
{
srand(time(NULL)); while (!ext) { for (unsigned i = 0; i < (count/3)*3; i+=3) { data[i] = ((rand() % 2001) * 0.001f) - 1.0f; data[i+1] = ((rand() % 2001) * 0.001f) - 1.0f; data[i+2] = 0.0f; } }
}
int main()
{
if (!glfwInit()) return 1; glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2); GLFWwindow* window = glfwCreateWindow(640, 480, "Test", NULL, NULL); glfwMakeContextCurrent(window); glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE); glewExperimental = GL_TRUE; glewInit(); GLuint vshader = glCreateShader(GL_VERTEX_SHADER); char const* source_pointer = vsource; glShaderSource (vshader,1,&source_pointer,NULL); glCompileShader(vshader); GLuint fshader = glCreateShader(GL_FRAGMENT_SHADER); source_pointer = fsource; glShaderSource (fshader,1,&source_pointer,NULL); glCompileShader(fshader); GLuint program = glCreateProgram(); glAttachShader(program,vshader); glAttachShader(program,fshader); glLinkProgram(program); GLuint VAO; glGenVertexArrays(1,&VAO); glBindVertexArray(VAO); GLuint VBO; glGenBuffers(1,&VBO); glBindBuffer(GL_ARRAY_BUFFER,VBO); glBufferData(GL_ARRAY_BUFFER,300*sizeof(float),NULL,GL_DYNAMIC_DRAW); void* ptr = glMapBuffer(GL_ARRAY_BUFFER,GL_WRITE_ONLY | GL_MAP_UNSYNCHRONIZED_BIT); GLint pos = glGetAttribLocation(program,"position\0"); glVertexAttribPointer(pos,3,GL_FLOAT,GL_FALSE,0,0); glEnableVertexAttribArray(pos); glUseProgram(program); std::thread thread1(gen_function,(float*)ptr,300); glPointSize(2.0f); do { glClear(GL_COLOR_BUFFER_BIT); glDrawArrays(GL_POINTS,0,100); glfwSwapBuffers(window); glfwPollEvents(); } while (glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS && glfwWindowShouldClose(window) == 0); ext = 1; thread1.join(); glDisableVertexAttribArray(pos); glUnmapBuffer(GL_ARRAY_BUFFER); glDeleteBuffers(1,&VBO); glDeleteVertexArrays(1,&VAO); glDeleteProgram(program); glDeleteShader(vshader); glDeleteShader(fshader); glfwTerminate(); return 0;
}
If I use open source driver(mesa(r600g)) then program draws without problems.
Hardware: 6480G + 7470M
OS: Kubuntu 14.10 daily
Driver: AMD Catalyst 14.6 jul11