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