[ANN] CImGui.jl - A Wrapper for Bloat-free Immediate Mode Graphical User interface(Dear ImGui)

Gnimuc · March 6, 2019, 4:50am

That’s probably due to the implementation of OpenGL backend is not very efficient. It queries a lot OpenGL global states in the rendering loop:

github.com

Gnimuc/CImGui.jl/blob/0c5d72d5066b54d37f50e08ae3f93dc7985103db/src/backend/OpenGL/impl.jl#L40-L59


      
          last_active_texture = GLint(0); @c glGetIntegerv(GL_ACTIVE_TEXTURE, &last_active_texture)
          glActiveTexture(GL_TEXTURE0)
          last_program = GLint(0); @c glGetIntegerv(GL_CURRENT_PROGRAM, &last_program)
          last_texture = GLint(0); @c glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture)
          last_sampler = GLint(0); @c glGetIntegerv(GL_SAMPLER_BINDING, &last_sampler)
          last_array_buffer = GLint(0); @c glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer)
          last_vertex_array = GLint(0); @c glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array)
          last_polygon_mode = GLint[0,0]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode)
          last_viewport = GLint[0,0,0,0]; glGetIntegerv(GL_VIEWPORT, last_viewport)
          last_scissor_box = GLint[0,0,0,0]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box)
          last_blend_src_rgb = GLint(0); @c glGetIntegerv(GL_BLEND_SRC_RGB, &last_blend_src_rgb)
          last_blend_dst_rgb = GLint(0); @c glGetIntegerv(GL_BLEND_DST_RGB, &last_blend_dst_rgb)
          last_blend_src_alpha = GLint(0); @c glGetIntegerv(GL_BLEND_SRC_ALPHA, &last_blend_src_alpha)
          last_blend_dst_alpha = GLint(0); @c glGetIntegerv(GL_BLEND_DST_ALPHA, &last_blend_dst_alpha)
          last_blend_equation_rgb = GLint(0); @c glGetIntegerv(GL_BLEND_EQUATION_RGB, &last_blend_equation_rgb)
          last_blend_equation_alpha = GLint(0); @c glGetIntegerv(GL_BLEND_EQUATION_ALPHA, &last_blend_equation_alpha)
          last_enable_blend = glIsEnabled(GL_BLEND)
          last_enable_cull_face = glIsEnabled(GL_CULL_FACE)
          last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST)
          last_enable_scissor_test = glIsEnabled(GL_SCISSOR_TEST)

This implementation is copied from Dear ImGui which maybe a trade-off bwteen correctness and performance.