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imgui/examples/imgui_impl_opengl3.cpp

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// 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] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID in imgui.cpp.
// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2018-07-10: OpenGL: Support for more GLSL versions (based on the GLSL version string). Added error output when shaders fail to compile/link.
// 2018-06-08: Misc: Extracted imgui_impl_opengl3.cpp/.h away from the old combined GLFW/SDL+OpenGL3 examples.
// 2018-06-08: OpenGL: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
// 2018-05-25: OpenGL: Removed unnecessary backup/restore of GL_ELEMENT_ARRAY_BUFFER_BINDING since this is part of the VAO state.
// 2018-05-14: OpenGL: Making the call to glBindSampler() optional so 3.2 context won't fail if the function is a NULL pointer.
// 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)
//----------------------------------------
// OpenGL GLSL GLSL
// version version string
//----------------------------------------
// 2.0 110 "#version 110"
// 2.1 120
// 3.0 130
// 3.1 140
// 3.2 150 "#version 150"
// 3.3 330
// 4.0 400
// 4.1 410
// 4.2 420
// 4.3 430
// ES 2.0 100 "#version 100"
// ES 3.0 300 "#version 300 es"
//----------------------------------------
#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS
#endif
#include "imgui.h"
#include "imgui_impl_opengl3.h"
#include <stdio.h>
#if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
#include <stddef.h> // intptr_t
#else
#include <stdint.h> // intptr_t
#endif
#include <GL/gl3w.h> // This example is using gl3w to access OpenGL functions. You may use another OpenGL loader/header such as: glew, glext, glad, glLoadGen, etc.
//#include <glew.h>
//#include <glext.h>
//#include <glad/glad.h>
// OpenGL Data
static char g_GlslVersionString[32] = "";
static GLuint g_FontTexture = 0;
static GLuint 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;
// Functions
bool ImGui_ImplOpenGL3_Init(const char* glsl_version)
{
// Store GLSL version string so we can refer to it later in case we recreate shaders. Note: GLSL version is NOT the same as GL version. Leave this to NULL if unsure.
if (glsl_version == NULL)
glsl_version = "#version 130";
IM_ASSERT((int)strlen(glsl_version) + 2 < IM_ARRAYSIZE(g_GlslVersionString));
strcpy(g_GlslVersionString, glsl_version);
strcat(g_GlslVersionString, "\n");
return true;
}
void ImGui_ImplOpenGL3_Shutdown()
{
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_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]);
if (glBindSampler) glBindSampler(0, 0); // We use combined texture/sampler state. Applications using GL 3.3 may set that otherwise.
// 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 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 - pos.x, pcmd->ClipRect.y - pos.y, pcmd->ClipRect.z - pos.x, pcmd->ClipRect.w - 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);
if (glBindSampler) glBindSampler(0, last_sampler);
glActiveTexture(last_active_texture);
glBindVertexArray(last_vertex_array);
glBindBuffer(GL_ARRAY_BUFFER, last_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;
}
}
// If you get an error please report on github. You may try different GL context version or GLSL version.
static bool CheckShader(GLuint handle, const char* desc)
{
GLint status = 0, log_length = 0;
glGetShaderiv(handle, GL_COMPILE_STATUS, &status);
glGetShaderiv(handle, GL_INFO_LOG_LENGTH, &log_length);
if (status == GL_FALSE)
fprintf(stderr, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to compile %s!\n", desc);
if (log_length > 0)
{
ImVector<char> buf;
buf.resize((int)(log_length + 1));
glGetShaderInfoLog(handle, log_length, NULL, (GLchar*)buf.begin());
fprintf(stderr, "%s\n", buf.begin());
}
return status == GL_TRUE;
}
// If you get an error please report on github. You may try different GL context version or GLSL version.
static bool CheckProgram(GLuint handle, const char* desc)
{
GLint status = 0, log_length = 0;
glGetProgramiv(handle, GL_LINK_STATUS, &status);
glGetProgramiv(handle, GL_INFO_LOG_LENGTH, &log_length);
if (status == GL_FALSE)
fprintf(stderr, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to link %s!\n", desc);
if (log_length > 0)
{
ImVector<char> buf;
buf.resize((int)(log_length + 1));
glGetProgramInfoLog(handle, log_length, NULL, (GLchar*)buf.begin());
fprintf(stderr, "%s\n", buf.begin());
}
return status == GL_TRUE;
}
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);
// Parse GLSL version string
int glsl_version = 130;
sscanf(g_GlslVersionString, "#version %d", &glsl_version);
const GLchar* vertex_shader_glsl_120 =
"uniform mat4 ProjMtx;\n"
"attribute vec2 Position;\n"
"attribute vec2 UV;\n"
"attribute vec4 Color;\n"
"varying vec2 Frag_UV;\n"
"varying 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* vertex_shader_glsl_130 =
"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_glsl_120 =
"#ifdef GL_ES\n"
" precision mediump float;\n"
"#endif\n"
"uniform sampler2D Texture;\n"
"varying vec2 Frag_UV;\n"
"varying vec4 Frag_Color;\n"
"void main()\n"
"{\n"
" gl_FragColor = Frag_Color * texture2D(Texture, Frag_UV.st);\n"
"}\n";
const GLchar* fragment_shader_glsl_130 =
"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";
// Select shaders matching our GLSL versions
const GLchar* vertex_shader = NULL;
const GLchar* fragment_shader = NULL;
if (glsl_version < 130)
{
vertex_shader = vertex_shader_glsl_120;
fragment_shader = fragment_shader_glsl_120;
}
else
{
vertex_shader = vertex_shader_glsl_130;
fragment_shader = fragment_shader_glsl_130;
}
// Create shaders
const GLchar* vertex_shader_with_version[2] = { g_GlslVersionString, vertex_shader };
g_VertHandle = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(g_VertHandle, 2, vertex_shader_with_version, NULL);
glCompileShader(g_VertHandle);
CheckShader(g_VertHandle, "vertex shader");
const GLchar* fragment_shader_with_version[2] = { g_GlslVersionString, fragment_shader };
g_FragHandle = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(g_FragHandle, 2, fragment_shader_with_version, NULL);
glCompileShader(g_FragHandle);
CheckShader(g_FragHandle, "fragment shader");
g_ShaderHandle = glCreateProgram();
glAttachShader(g_ShaderHandle, g_VertHandle);
glAttachShader(g_ShaderHandle, g_FragHandle);
glLinkProgram(g_ShaderHandle);
CheckProgram(g_ShaderHandle, "shader program");
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");
// Create buffers
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();
}
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