// ImGui Renderer for: OpenGL3 (modern OpenGL with shaders / programmatic pipeline) // This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..) // (Note: We are using GL3W as a helper library to access OpenGL functions since there is no standard header to access modern OpenGL functions easily. Alternatives are GLEW, Glad, etc..) // Implemented features: // [X] User texture binding. Use 'GLUint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID in imgui.cpp. // [X] Multi-viewport rendering (when ImGuiConfigFlags_EnableViewports is enabled). // CHANGELOG // (minor and older changes stripped away, please see git history for details) // 2018-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface. // 2018-XX-XX: OpenGL: Offset projection matrix and clipping rectangle by draw_data->DisplayPos (which will be non-zero for multi-viewport applications). // 2018-03-06: OpenGL: Added const char* glsl_version parameter to ImGui_ImplOpenGL3_Init() so user can override the GLSL version e.g. "#version 150". // 2018-02-23: OpenGL: Create the VAO in the render function so the setup can more easily be used with multiple shared GL context. // 2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplSdlGL3_RenderDrawData() in the .h file so you can call it yourself. // 2018-01-07: OpenGL: Changed GLSL shader version from 330 to 150. // 2017-09-01: OpenGL: Save and restore current bound sampler. Save and restore current polygon mode. // 2017-05-01: OpenGL: Fixed save and restore of current blend func state. // 2017-05-01: OpenGL: Fixed save and restore of current GL_ACTIVE_TEXTURE. // 2016-09-05: OpenGL: Fixed save and restore of current scissor rectangle. // 2016-07-29: OpenGL: Explicitly setting GL_UNPACK_ROW_LENGTH to reduce issues because SDL changes it. (#752) #if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS) #define _CRT_SECURE_NO_WARNINGS #endif #include "imgui.h" #include "imgui_impl_opengl3.h" #include // This example is using gl3w to access OpenGL functions (because it is small). You may use glew/glad/glLoadGen/etc. whatever already works for you. // OpenGL Data static char g_GlslVersion[32] = "#version 150"; static GLuint g_FontTexture = 0; static int g_ShaderHandle = 0, g_VertHandle = 0, g_FragHandle = 0; static int g_AttribLocationTex = 0, g_AttribLocationProjMtx = 0; static int g_AttribLocationPosition = 0, g_AttribLocationUV = 0, g_AttribLocationColor = 0; static unsigned int g_VboHandle = 0, g_ElementsHandle = 0; // Forward Declarations static void ImGui_ImplOpenGL3_InitPlatformInterface(); static void ImGui_ImplOpenGL3_ShutdownPlatformInterface(); // Functions bool ImGui_ImplOpenGL3_Init(const char* glsl_version) { // Store GL version string so we can refer to it later in case we recreate shaders. if (glsl_version == NULL) glsl_version = "#version 150"; IM_ASSERT((int)strlen(glsl_version) + 2 < IM_ARRAYSIZE(g_GlslVersion)); strcpy(g_GlslVersion, glsl_version); strcat(g_GlslVersion, "\n"); ImGuiIO& io = ImGui::GetIO(); io.ConfigFlags |= ImGuiConfigFlags_RendererHasViewports; if (io.ConfigFlags & ImGuiConfigFlags_EnableViewports) ImGui_ImplOpenGL3_InitPlatformInterface(); return true; } void ImGui_ImplOpenGL3_Shutdown() { ImGui_ImplOpenGL3_ShutdownPlatformInterface(); ImGui_ImplOpenGL3_DestroyDeviceObjects(); } void ImGui_ImplOpenGL3_NewFrame() { if (!g_FontTexture) ImGui_ImplOpenGL3_CreateDeviceObjects(); } // OpenGL3 Render function. // (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop) // Note that this implementation is little overcomplicated because we are saving/setting up/restoring every OpenGL state explicitly, in order to be able to run within any OpenGL engine that doesn't do so. void ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data) { // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates) ImGuiIO& io = ImGui::GetIO(); int fb_width = (int)(draw_data->DisplaySize.x * io.DisplayFramebufferScale.x); int fb_height = (int)(draw_data->DisplaySize.y * io.DisplayFramebufferScale.y); if (fb_width <= 0 || fb_height <= 0) return; draw_data->ScaleClipRects(io.DisplayFramebufferScale); // Backup GL state GLenum last_active_texture; glGetIntegerv(GL_ACTIVE_TEXTURE, (GLint*)&last_active_texture); glActiveTexture(GL_TEXTURE0); GLint last_program; glGetIntegerv(GL_CURRENT_PROGRAM, &last_program); GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture); GLint last_sampler; glGetIntegerv(GL_SAMPLER_BINDING, &last_sampler); GLint last_array_buffer; glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer); GLint last_element_array_buffer; glGetIntegerv(GL_ELEMENT_ARRAY_BUFFER_BINDING, &last_element_array_buffer); GLint last_vertex_array; glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array); GLint last_polygon_mode[2]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode); GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport); GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box); GLenum last_blend_src_rgb; glGetIntegerv(GL_BLEND_SRC_RGB, (GLint*)&last_blend_src_rgb); GLenum last_blend_dst_rgb; glGetIntegerv(GL_BLEND_DST_RGB, (GLint*)&last_blend_dst_rgb); GLenum last_blend_src_alpha; glGetIntegerv(GL_BLEND_SRC_ALPHA, (GLint*)&last_blend_src_alpha); GLenum last_blend_dst_alpha; glGetIntegerv(GL_BLEND_DST_ALPHA, (GLint*)&last_blend_dst_alpha); GLenum last_blend_equation_rgb; glGetIntegerv(GL_BLEND_EQUATION_RGB, (GLint*)&last_blend_equation_rgb); GLenum last_blend_equation_alpha; glGetIntegerv(GL_BLEND_EQUATION_ALPHA, (GLint*)&last_blend_equation_alpha); GLboolean last_enable_blend = glIsEnabled(GL_BLEND); GLboolean last_enable_cull_face = glIsEnabled(GL_CULL_FACE); GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST); GLboolean last_enable_scissor_test = glIsEnabled(GL_SCISSOR_TEST); // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, polygon fill glEnable(GL_BLEND); glBlendEquation(GL_FUNC_ADD); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glDisable(GL_CULL_FACE); glDisable(GL_DEPTH_TEST); glEnable(GL_SCISSOR_TEST); glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); // Setup viewport, orthographic projection matrix // Our visible imgui space lies from draw_data->DisplayPps (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayMin is typically (0,0) for single viewport apps. glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height); float L = draw_data->DisplayPos.x; float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x; float T = draw_data->DisplayPos.y; float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y; const float ortho_projection[4][4] = { { 2.0f/(R-L), 0.0f, 0.0f, 0.0f }, { 0.0f, 2.0f/(T-B), 0.0f, 0.0f }, { 0.0f, 0.0f, -1.0f, 0.0f }, { (R+L)/(L-R), (T+B)/(B-T), 0.0f, 1.0f }, }; glUseProgram(g_ShaderHandle); glUniform1i(g_AttribLocationTex, 0); glUniformMatrix4fv(g_AttribLocationProjMtx, 1, GL_FALSE, &ortho_projection[0][0]); glBindSampler(0, 0); // Rely on combined texture/sampler state. // Recreate the VAO every time // (This is to easily allow multiple GL contexts. VAO are not shared among GL contexts, and we don't track creation/deletion of windows so we don't have an obvious key to use to cache them.) GLuint vao_handle = 0; glGenVertexArrays(1, &vao_handle); glBindVertexArray(vao_handle); glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle); glEnableVertexAttribArray(g_AttribLocationPosition); glEnableVertexAttribArray(g_AttribLocationUV); glEnableVertexAttribArray(g_AttribLocationColor); glVertexAttribPointer(g_AttribLocationPosition, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, pos)); glVertexAttribPointer(g_AttribLocationUV, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, uv)); glVertexAttribPointer(g_AttribLocationColor, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, col)); // Draw ImVec2 display_pos = draw_data->DisplayPos; for (int n = 0; n < draw_data->CmdListsCount; n++) { const ImDrawList* cmd_list = draw_data->CmdLists[n]; const ImDrawIdx* idx_buffer_offset = 0; glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle); glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)cmd_list->VtxBuffer.Size * sizeof(ImDrawVert), (const GLvoid*)cmd_list->VtxBuffer.Data, GL_STREAM_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_ElementsHandle); glBufferData(GL_ELEMENT_ARRAY_BUFFER, (GLsizeiptr)cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx), (const GLvoid*)cmd_list->IdxBuffer.Data, GL_STREAM_DRAW); for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++) { const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i]; if (pcmd->UserCallback) { // User callback (registered via ImDrawList::AddCallback) pcmd->UserCallback(cmd_list, pcmd); } else { ImVec4 clip_rect = ImVec4(pcmd->ClipRect.x - display_pos.x, pcmd->ClipRect.y - display_pos.y, pcmd->ClipRect.z - display_pos.x, pcmd->ClipRect.w - display_pos.y); if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f) { // Apply scissor/clipping rectangle glScissor((int)clip_rect.x, (int)(fb_height - clip_rect.w), (int)(clip_rect.z - clip_rect.x), (int)(clip_rect.w - clip_rect.y)); // Bind texture, Draw glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->TextureId); glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer_offset); } } idx_buffer_offset += pcmd->ElemCount; } } glDeleteVertexArrays(1, &vao_handle); // Restore modified GL state glUseProgram(last_program); glBindTexture(GL_TEXTURE_2D, last_texture); glBindSampler(0, last_sampler); glActiveTexture(last_active_texture); glBindVertexArray(last_vertex_array); glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, last_element_array_buffer); glBlendEquationSeparate(last_blend_equation_rgb, last_blend_equation_alpha); glBlendFuncSeparate(last_blend_src_rgb, last_blend_dst_rgb, last_blend_src_alpha, last_blend_dst_alpha); if (last_enable_blend) glEnable(GL_BLEND); else glDisable(GL_BLEND); if (last_enable_cull_face) glEnable(GL_CULL_FACE); else glDisable(GL_CULL_FACE); if (last_enable_depth_test) glEnable(GL_DEPTH_TEST); else glDisable(GL_DEPTH_TEST); if (last_enable_scissor_test) glEnable(GL_SCISSOR_TEST); else glDisable(GL_SCISSOR_TEST); glPolygonMode(GL_FRONT_AND_BACK, (GLenum)last_polygon_mode[0]); glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]); glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]); } bool ImGui_ImplOpenGL3_CreateFontsTexture() { // Build texture atlas ImGuiIO& io = ImGui::GetIO(); unsigned char* pixels; int width, height; io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height); // Load as RGBA 32-bits (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory. // Upload texture to graphics system GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture); glGenTextures(1, &g_FontTexture); glBindTexture(GL_TEXTURE_2D, g_FontTexture); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glPixelStorei(GL_UNPACK_ROW_LENGTH, 0); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels); // Store our identifier io.Fonts->TexID = (void *)(intptr_t)g_FontTexture; // Restore state glBindTexture(GL_TEXTURE_2D, last_texture); return true; } void ImGui_ImplOpenGL3_DestroyFontsTexture() { if (g_FontTexture) { ImGuiIO& io = ImGui::GetIO(); glDeleteTextures(1, &g_FontTexture); io.Fonts->TexID = 0; g_FontTexture = 0; } } bool ImGui_ImplOpenGL3_CreateDeviceObjects() { // Backup GL state GLint last_texture, last_array_buffer, last_vertex_array; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture); glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer); glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array); // Create shaders const GLchar *vertex_shader = "uniform mat4 ProjMtx;\n" "in vec2 Position;\n" "in vec2 UV;\n" "in vec4 Color;\n" "out vec2 Frag_UV;\n" "out vec4 Frag_Color;\n" "void main()\n" "{\n" " Frag_UV = UV;\n" " Frag_Color = Color;\n" " gl_Position = ProjMtx * vec4(Position.xy,0,1);\n" "}\n"; const GLchar* fragment_shader = "uniform sampler2D Texture;\n" "in vec2 Frag_UV;\n" "in vec4 Frag_Color;\n" "out vec4 Out_Color;\n" "void main()\n" "{\n" " Out_Color = Frag_Color * texture( Texture, Frag_UV.st);\n" "}\n"; const GLchar* vertex_shader_with_version[2] = { g_GlslVersion, vertex_shader }; const GLchar* fragment_shader_with_version[2] = { g_GlslVersion, fragment_shader }; g_ShaderHandle = glCreateProgram(); g_VertHandle = glCreateShader(GL_VERTEX_SHADER); g_FragHandle = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(g_VertHandle, 2, vertex_shader_with_version, NULL); glShaderSource(g_FragHandle, 2, fragment_shader_with_version, NULL); glCompileShader(g_VertHandle); glCompileShader(g_FragHandle); glAttachShader(g_ShaderHandle, g_VertHandle); glAttachShader(g_ShaderHandle, g_FragHandle); glLinkProgram(g_ShaderHandle); g_AttribLocationTex = glGetUniformLocation(g_ShaderHandle, "Texture"); g_AttribLocationProjMtx = glGetUniformLocation(g_ShaderHandle, "ProjMtx"); g_AttribLocationPosition = glGetAttribLocation(g_ShaderHandle, "Position"); g_AttribLocationUV = glGetAttribLocation(g_ShaderHandle, "UV"); g_AttribLocationColor = glGetAttribLocation(g_ShaderHandle, "Color"); glGenBuffers(1, &g_VboHandle); glGenBuffers(1, &g_ElementsHandle); ImGui_ImplOpenGL3_CreateFontsTexture(); // Restore modified GL state glBindTexture(GL_TEXTURE_2D, last_texture); glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer); glBindVertexArray(last_vertex_array); return true; } void ImGui_ImplOpenGL3_DestroyDeviceObjects() { if (g_VboHandle) glDeleteBuffers(1, &g_VboHandle); if (g_ElementsHandle) glDeleteBuffers(1, &g_ElementsHandle); g_VboHandle = g_ElementsHandle = 0; if (g_ShaderHandle && g_VertHandle) glDetachShader(g_ShaderHandle, g_VertHandle); if (g_VertHandle) glDeleteShader(g_VertHandle); g_VertHandle = 0; if (g_ShaderHandle && g_FragHandle) glDetachShader(g_ShaderHandle, g_FragHandle); if (g_FragHandle) glDeleteShader(g_FragHandle); g_FragHandle = 0; if (g_ShaderHandle) glDeleteProgram(g_ShaderHandle); g_ShaderHandle = 0; ImGui_ImplOpenGL3_DestroyFontsTexture(); } //-------------------------------------------------------------------------------------------------------- // Platform Interface (Optional, for multi-viewport support) //-------------------------------------------------------------------------------------------------------- static void ImGui_ImplOpenGL3_RenderWindow(ImGuiViewport* viewport, void*) { if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear)) { ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f); glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w); glClear(GL_COLOR_BUFFER_BIT); } ImGui_ImplOpenGL3_RenderDrawData(viewport->DrawData); } static void ImGui_ImplOpenGL3_InitPlatformInterface() { ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO(); platform_io.Renderer_RenderWindow = ImGui_ImplOpenGL3_RenderWindow; } static void ImGui_ImplOpenGL3_ShutdownPlatformInterface() { ImGui::DestroyPlatformWindows(); }