gl_time_query.cxx

#include "gl_time_query.h"
 
#include <cgv_gl/gl/gl.h>
 
namespace cgv {
    namespace render {
        namespace gl {
 
gl_time_query::gl_time_query()
{
}
 
gl_time_query::~gl_time_query()
{
    if(is_initialized())
        destruct(*ctx_ptr);
}
 
bool gl_time_query::init(context& ctx)
{
    if(!ensure_glew_initialized()) {
        last_error = "could not initialize glew";
        return false;
    }
    if(!GLEW_ARB_timer_query) {
        last_error = "missing ARB timer query extension";
        return false;
    }
    
    glGenQueries(1, &query);
 
    ctx_ptr = &ctx;
    return query != 0;
}
 
void gl_time_query::destruct(context& ctx)
{
    glDeleteQueries(1, &query);
    query = 0;
    
    ctx_ptr = nullptr;
}
 
bool gl_time_query::is_initialized() const
{
    return ctx_ptr != nullptr;
}
 
void gl_time_query::begin_scope() const
{
    glBeginQuery(GL_TIME_ELAPSED, query);
}
 
void gl_time_query::end_scope() const
{
    glEndQuery(GL_TIME_ELAPSED);
}
 
double gl_time_query::collect() const
{
    GLint done = false;
    while(!done)
        glGetQueryObjectiv(query, GL_QUERY_RESULT_AVAILABLE, &done);
 
    GLuint64 elapsed_time = 0;
    glGetQueryObjectui64v(query, GL_QUERY_RESULT, &elapsed_time);
 
    return double(elapsed_time);
}
 
void gl_time_query::begin() const
{
    glBeginQuery(GL_TIME_ELAPSED, query);
}
 
double gl_time_query::end() const
{
    glEndQuery(GL_TIME_ELAPSED);
 
    GLint done = false;
    while(!done)
        glGetQueryObjectiv(query, GL_QUERY_RESULT_AVAILABLE, &done);
 
    GLuint64 elapsed_time = 0;
    glGetQueryObjectui64v(query, GL_QUERY_RESULT, &elapsed_time);
 
    return double(elapsed_time);
}
 
        } // namespace cgv
    } // namespace render
} // namespace gl