1 // ImGui Renderer for: OpenGL3 (modern OpenGL with shaders / programmatic pipeline)
2 // This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..)
3 // (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..)
5 // Implemented features:
6 // [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID in imgui.cpp.
8 // You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
9 // If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
10 // https://github.com/ocornut/imgui
13 // (minor and older changes stripped away, please see git history for details)
14 // 2018-07-10: OpenGL: Support for more GLSL versions (based on the GLSL version string). Added error output when shaders fail to compile/link.
15 // 2018-06-08: Misc: Extracted imgui_impl_opengl3.cpp/.h away from the old combined GLFW/SDL+OpenGL3 examples.
16 // 2018-06-08: OpenGL: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
17 // 2018-05-25: OpenGL: Removed unnecessary backup/restore of GL_ELEMENT_ARRAY_BUFFER_BINDING since this is part of the VAO state.
18 // 2018-05-14: OpenGL: Making the call to glBindSampler() optional so 3.2 context won't fail if the function is a NULL pointer.
19 // 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".
20 // 2018-02-23: OpenGL: Create the VAO in the render function so the setup can more easily be used with multiple shared GL context.
21 // 2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplSdlGL3_RenderDrawData() in the .h file so you can call it yourself.
22 // 2018-01-07: OpenGL: Changed GLSL shader version from 330 to 150.
23 // 2017-09-01: OpenGL: Save and restore current bound sampler. Save and restore current polygon mode.
24 // 2017-05-01: OpenGL: Fixed save and restore of current blend func state.
25 // 2017-05-01: OpenGL: Fixed save and restore of current GL_ACTIVE_TEXTURE.
26 // 2016-09-05: OpenGL: Fixed save and restore of current scissor rectangle.
27 // 2016-07-29: OpenGL: Explicitly setting GL_UNPACK_ROW_LENGTH to reduce issues because SDL changes it. (#752)
29 //----------------------------------------
31 // version version string
32 //----------------------------------------
33 // 2.0 110 "#version 110"
37 // 3.2 150 "#version 150"
43 // ES 2.0 100 "#version 100"
44 // ES 3.0 300 "#version 300 es"
45 //----------------------------------------
47 #if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
48 #define _CRT_SECURE_NO_WARNINGS
51 #include "imgui/imgui.h"
52 #include "imgui_impl_opengl3.h"
54 #if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
55 #include <stddef.h> // intptr_t
57 #include <stdint.h> // intptr_t
61 //#include "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.
64 //#include <glad/glad.h>
67 static char g_GlslVersionString
[32] = "";
68 static GLuint g_FontTexture
= 0;
69 static GLuint g_ShaderHandle
= 0, g_VertHandle
= 0, g_FragHandle
= 0;
70 static int g_AttribLocationTex
= 0, g_AttribLocationProjMtx
= 0;
71 static int g_AttribLocationPosition
= 0, g_AttribLocationUV
= 0, g_AttribLocationColor
= 0;
72 static unsigned int g_VboHandle
= 0, g_ElementsHandle
= 0;
75 bool ImGui_ImplOpenGL3_Init(const char* glsl_version
)
77 // 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.
78 if (glsl_version
== NULL
)
79 glsl_version
= "#version 130";
80 IM_ASSERT((int)strlen(glsl_version
) + 2 < IM_ARRAYSIZE(g_GlslVersionString
));
81 strcpy(g_GlslVersionString
, glsl_version
);
82 strcat(g_GlslVersionString
, "\n");
86 void ImGui_ImplOpenGL3_Shutdown()
88 ImGui_ImplOpenGL3_DestroyDeviceObjects();
91 void ImGui_ImplOpenGL3_NewFrame()
94 ImGui_ImplOpenGL3_CreateDeviceObjects();
97 // OpenGL3 Render function.
98 // (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop)
99 // 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.
100 void ImGui_ImplOpenGL3_RenderDrawData(ImDrawData
* draw_data
)
102 // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
103 ImGuiIO
& io
= ImGui::GetIO();
104 int fb_width
= (int)(draw_data
->DisplaySize
.x
* io
.DisplayFramebufferScale
.x
);
105 int fb_height
= (int)(draw_data
->DisplaySize
.y
* io
.DisplayFramebufferScale
.y
);
106 if (fb_width
<= 0 || fb_height
<= 0)
108 draw_data
->ScaleClipRects(io
.DisplayFramebufferScale
);
111 GLenum last_active_texture
; glGetIntegerv(GL_ACTIVE_TEXTURE
, (GLint
*)&last_active_texture
);
112 glActiveTexture(GL_TEXTURE0
);
113 GLint last_program
; glGetIntegerv(GL_CURRENT_PROGRAM
, &last_program
);
114 GLint last_texture
; glGetIntegerv(GL_TEXTURE_BINDING_2D
, &last_texture
);
115 GLint last_sampler
; glGetIntegerv(GL_SAMPLER_BINDING
, &last_sampler
);
116 GLint last_array_buffer
; glGetIntegerv(GL_ARRAY_BUFFER_BINDING
, &last_array_buffer
);
117 GLint last_vertex_array
; glGetIntegerv(GL_VERTEX_ARRAY_BINDING
, &last_vertex_array
);
118 GLint last_polygon_mode
[2]; glGetIntegerv(GL_POLYGON_MODE
, last_polygon_mode
);
119 GLint last_viewport
[4]; glGetIntegerv(GL_VIEWPORT
, last_viewport
);
120 GLint last_scissor_box
[4]; glGetIntegerv(GL_SCISSOR_BOX
, last_scissor_box
);
121 GLenum last_blend_src_rgb
; glGetIntegerv(GL_BLEND_SRC_RGB
, (GLint
*)&last_blend_src_rgb
);
122 GLenum last_blend_dst_rgb
; glGetIntegerv(GL_BLEND_DST_RGB
, (GLint
*)&last_blend_dst_rgb
);
123 GLenum last_blend_src_alpha
; glGetIntegerv(GL_BLEND_SRC_ALPHA
, (GLint
*)&last_blend_src_alpha
);
124 GLenum last_blend_dst_alpha
; glGetIntegerv(GL_BLEND_DST_ALPHA
, (GLint
*)&last_blend_dst_alpha
);
125 GLenum last_blend_equation_rgb
; glGetIntegerv(GL_BLEND_EQUATION_RGB
, (GLint
*)&last_blend_equation_rgb
);
126 GLenum last_blend_equation_alpha
; glGetIntegerv(GL_BLEND_EQUATION_ALPHA
, (GLint
*)&last_blend_equation_alpha
);
127 GLboolean last_enable_blend
= glIsEnabled(GL_BLEND
);
128 GLboolean last_enable_cull_face
= glIsEnabled(GL_CULL_FACE
);
129 GLboolean last_enable_depth_test
= glIsEnabled(GL_DEPTH_TEST
);
130 GLboolean last_enable_scissor_test
= glIsEnabled(GL_SCISSOR_TEST
);
132 // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, polygon fill
134 glBlendEquation(GL_FUNC_ADD
);
135 glBlendFunc(GL_SRC_ALPHA
, GL_ONE_MINUS_SRC_ALPHA
);
136 glDisable(GL_CULL_FACE
);
137 glDisable(GL_DEPTH_TEST
);
138 glEnable(GL_SCISSOR_TEST
);
139 glPolygonMode(GL_FRONT_AND_BACK
, GL_FILL
);
141 // Setup viewport, orthographic projection matrix
142 // 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.
143 glViewport(0, 0, (GLsizei
)fb_width
, (GLsizei
)fb_height
);
144 float L
= draw_data
->DisplayPos
.x
;
145 float R
= draw_data
->DisplayPos
.x
+ draw_data
->DisplaySize
.x
;
146 float T
= draw_data
->DisplayPos
.y
;
147 float B
= draw_data
->DisplayPos
.y
+ draw_data
->DisplaySize
.y
;
148 const float ortho_projection
[4][4] =
150 { 2.0f
/(R
-L
), 0.0f
, 0.0f
, 0.0f
},
151 { 0.0f
, 2.0f
/(T
-B
), 0.0f
, 0.0f
},
152 { 0.0f
, 0.0f
, -1.0f
, 0.0f
},
153 { (R
+L
)/(L
-R
), (T
+B
)/(B
-T
), 0.0f
, 1.0f
},
155 glUseProgram(g_ShaderHandle
);
156 glUniform1i(g_AttribLocationTex
, 0);
157 glUniformMatrix4fv(g_AttribLocationProjMtx
, 1, GL_FALSE
, &ortho_projection
[0][0]);
158 if (glBindSampler
) glBindSampler(0, 0); // We use combined texture/sampler state. Applications using GL 3.3 may set that otherwise.
160 // Recreate the VAO every time
161 // (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.)
162 GLuint vao_handle
= 0;
163 glGenVertexArrays(1, &vao_handle
);
164 glBindVertexArray(vao_handle
);
165 glBindBuffer(GL_ARRAY_BUFFER
, g_VboHandle
);
166 glEnableVertexAttribArray(g_AttribLocationPosition
);
167 glEnableVertexAttribArray(g_AttribLocationUV
);
168 glEnableVertexAttribArray(g_AttribLocationColor
);
169 glVertexAttribPointer(g_AttribLocationPosition
, 2, GL_FLOAT
, GL_FALSE
, sizeof(ImDrawVert
), (GLvoid
*)IM_OFFSETOF(ImDrawVert
, pos
));
170 glVertexAttribPointer(g_AttribLocationUV
, 2, GL_FLOAT
, GL_FALSE
, sizeof(ImDrawVert
), (GLvoid
*)IM_OFFSETOF(ImDrawVert
, uv
));
171 glVertexAttribPointer(g_AttribLocationColor
, 4, GL_UNSIGNED_BYTE
, GL_TRUE
, sizeof(ImDrawVert
), (GLvoid
*)IM_OFFSETOF(ImDrawVert
, col
));
174 ImVec2 pos
= draw_data
->DisplayPos
;
175 for (int n
= 0; n
< draw_data
->CmdListsCount
; n
++)
177 const ImDrawList
* cmd_list
= draw_data
->CmdLists
[n
];
178 const ImDrawIdx
* idx_buffer_offset
= 0;
180 glBindBuffer(GL_ARRAY_BUFFER
, g_VboHandle
);
181 glBufferData(GL_ARRAY_BUFFER
, (GLsizeiptr
)cmd_list
->VtxBuffer
.Size
* sizeof(ImDrawVert
), (const GLvoid
*)cmd_list
->VtxBuffer
.Data
, GL_STREAM_DRAW
);
183 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER
, g_ElementsHandle
);
184 glBufferData(GL_ELEMENT_ARRAY_BUFFER
, (GLsizeiptr
)cmd_list
->IdxBuffer
.Size
* sizeof(ImDrawIdx
), (const GLvoid
*)cmd_list
->IdxBuffer
.Data
, GL_STREAM_DRAW
);
186 for (int cmd_i
= 0; cmd_i
< cmd_list
->CmdBuffer
.Size
; cmd_i
++)
188 const ImDrawCmd
* pcmd
= &cmd_list
->CmdBuffer
[cmd_i
];
189 if (pcmd
->UserCallback
)
191 // User callback (registered via ImDrawList::AddCallback)
192 pcmd
->UserCallback(cmd_list
, pcmd
);
196 ImVec4 clip_rect
= ImVec4(pcmd
->ClipRect
.x
- pos
.x
, pcmd
->ClipRect
.y
- pos
.y
, pcmd
->ClipRect
.z
- pos
.x
, pcmd
->ClipRect
.w
- pos
.y
);
197 if (clip_rect
.x
< fb_width
&& clip_rect
.y
< fb_height
&& clip_rect
.z
>= 0.0f
&& clip_rect
.w
>= 0.0f
)
199 // Apply scissor/clipping rectangle
200 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
));
202 // Bind texture, Draw
203 glBindTexture(GL_TEXTURE_2D
, (GLuint
)(intptr_t)pcmd
->TextureId
);
204 glDrawElements(GL_TRIANGLES
, (GLsizei
)pcmd
->ElemCount
, sizeof(ImDrawIdx
) == 2 ? GL_UNSIGNED_SHORT
: GL_UNSIGNED_INT
, idx_buffer_offset
);
207 idx_buffer_offset
+= pcmd
->ElemCount
;
210 glDeleteVertexArrays(1, &vao_handle
);
212 // Restore modified GL state
213 glUseProgram(last_program
);
214 glBindTexture(GL_TEXTURE_2D
, last_texture
);
215 if (glBindSampler
) glBindSampler(0, last_sampler
);
216 glActiveTexture(last_active_texture
);
217 glBindVertexArray(last_vertex_array
);
218 glBindBuffer(GL_ARRAY_BUFFER
, last_array_buffer
);
219 glBlendEquationSeparate(last_blend_equation_rgb
, last_blend_equation_alpha
);
220 glBlendFuncSeparate(last_blend_src_rgb
, last_blend_dst_rgb
, last_blend_src_alpha
, last_blend_dst_alpha
);
221 if (last_enable_blend
) glEnable(GL_BLEND
); else glDisable(GL_BLEND
);
222 if (last_enable_cull_face
) glEnable(GL_CULL_FACE
); else glDisable(GL_CULL_FACE
);
223 if (last_enable_depth_test
) glEnable(GL_DEPTH_TEST
); else glDisable(GL_DEPTH_TEST
);
224 if (last_enable_scissor_test
) glEnable(GL_SCISSOR_TEST
); else glDisable(GL_SCISSOR_TEST
);
225 glPolygonMode(GL_FRONT_AND_BACK
, (GLenum
)last_polygon_mode
[0]);
226 glViewport(last_viewport
[0], last_viewport
[1], (GLsizei
)last_viewport
[2], (GLsizei
)last_viewport
[3]);
227 glScissor(last_scissor_box
[0], last_scissor_box
[1], (GLsizei
)last_scissor_box
[2], (GLsizei
)last_scissor_box
[3]);
230 bool ImGui_ImplOpenGL3_CreateFontsTexture()
232 // Build texture atlas
233 ImGuiIO
& io
= ImGui::GetIO();
234 unsigned char* pixels
;
236 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.
238 // Upload texture to graphics system
240 glGetIntegerv(GL_TEXTURE_BINDING_2D
, &last_texture
);
241 glGenTextures(1, &g_FontTexture
);
242 glBindTexture(GL_TEXTURE_2D
, g_FontTexture
);
243 glTexParameteri(GL_TEXTURE_2D
, GL_TEXTURE_MIN_FILTER
, GL_LINEAR
);
244 glTexParameteri(GL_TEXTURE_2D
, GL_TEXTURE_MAG_FILTER
, GL_LINEAR
);
245 glPixelStorei(GL_UNPACK_ROW_LENGTH
, 0);
246 glTexImage2D(GL_TEXTURE_2D
, 0, GL_RGBA
, width
, height
, 0, GL_RGBA
, GL_UNSIGNED_BYTE
, pixels
);
248 // Store our identifier
249 io
.Fonts
->TexID
= (void *)(intptr_t)g_FontTexture
;
252 glBindTexture(GL_TEXTURE_2D
, last_texture
);
257 void ImGui_ImplOpenGL3_DestroyFontsTexture()
261 ImGuiIO
& io
= ImGui::GetIO();
262 glDeleteTextures(1, &g_FontTexture
);
268 // If you get an error please report on github. You may try different GL context version or GLSL version.
269 static bool CheckShader(GLuint handle
, const char* desc
)
271 GLint status
= 0, log_length
= 0;
272 glGetShaderiv(handle
, GL_COMPILE_STATUS
, &status
);
273 glGetShaderiv(handle
, GL_INFO_LOG_LENGTH
, &log_length
);
274 if (status
== GL_FALSE
)
275 fprintf(stderr
, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to compile %s!\n", desc
);
279 buf
.resize((int)(log_length
+ 1));
280 glGetShaderInfoLog(handle
, log_length
, NULL
, (GLchar
*)buf
.begin());
281 fprintf(stderr
, "%s\n", buf
.begin());
283 return status
== GL_TRUE
;
286 // If you get an error please report on github. You may try different GL context version or GLSL version.
287 static bool CheckProgram(GLuint handle
, const char* desc
)
289 GLint status
= 0, log_length
= 0;
290 glGetProgramiv(handle
, GL_LINK_STATUS
, &status
);
291 glGetProgramiv(handle
, GL_INFO_LOG_LENGTH
, &log_length
);
292 if (status
== GL_FALSE
)
293 fprintf(stderr
, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to link %s!\n", desc
);
297 buf
.resize((int)(log_length
+ 1));
298 glGetProgramInfoLog(handle
, log_length
, NULL
, (GLchar
*)buf
.begin());
299 fprintf(stderr
, "%s\n", buf
.begin());
301 return status
== GL_TRUE
;
304 bool ImGui_ImplOpenGL3_CreateDeviceObjects()
307 GLint last_texture
, last_array_buffer
, last_vertex_array
;
308 glGetIntegerv(GL_TEXTURE_BINDING_2D
, &last_texture
);
309 glGetIntegerv(GL_ARRAY_BUFFER_BINDING
, &last_array_buffer
);
310 glGetIntegerv(GL_VERTEX_ARRAY_BINDING
, &last_vertex_array
);
312 // Parse GLSL version string
313 int glsl_version
= 130;
314 sscanf(g_GlslVersionString
, "#version %d", &glsl_version
);
316 const GLchar
* vertex_shader_glsl_120
=
317 "uniform mat4 ProjMtx;\n"
318 "attribute vec2 Position;\n"
319 "attribute vec2 UV;\n"
320 "attribute vec4 Color;\n"
321 "varying vec2 Frag_UV;\n"
322 "varying vec4 Frag_Color;\n"
326 " Frag_Color = Color;\n"
327 " gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
330 const GLchar
* vertex_shader_glsl_130
=
331 "uniform mat4 ProjMtx;\n"
332 "in vec2 Position;\n"
335 "out vec2 Frag_UV;\n"
336 "out vec4 Frag_Color;\n"
340 " Frag_Color = Color;\n"
341 " gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
344 const GLchar
* fragment_shader_glsl_120
=
346 " precision mediump float;\n"
348 "uniform sampler2D Texture;\n"
349 "varying vec2 Frag_UV;\n"
350 "varying vec4 Frag_Color;\n"
353 " gl_FragColor = Frag_Color * texture2D(Texture, Frag_UV.st);\n"
356 const GLchar
* fragment_shader_glsl_130
=
357 "uniform sampler2D Texture;\n"
359 "in vec4 Frag_Color;\n"
360 "out vec4 Out_Color;\n"
363 " Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
366 // Select shaders matching our GLSL versions
367 const GLchar
* vertex_shader
= NULL
;
368 const GLchar
* fragment_shader
= NULL
;
369 if (glsl_version
< 130)
371 vertex_shader
= vertex_shader_glsl_120
;
372 fragment_shader
= fragment_shader_glsl_120
;
376 vertex_shader
= vertex_shader_glsl_130
;
377 fragment_shader
= fragment_shader_glsl_130
;
381 const GLchar
* vertex_shader_with_version
[2] = { g_GlslVersionString
, vertex_shader
};
382 g_VertHandle
= glCreateShader(GL_VERTEX_SHADER
);
383 glShaderSource(g_VertHandle
, 2, vertex_shader_with_version
, NULL
);
384 glCompileShader(g_VertHandle
);
385 CheckShader(g_VertHandle
, "vertex shader");
387 const GLchar
* fragment_shader_with_version
[2] = { g_GlslVersionString
, fragment_shader
};
388 g_FragHandle
= glCreateShader(GL_FRAGMENT_SHADER
);
389 glShaderSource(g_FragHandle
, 2, fragment_shader_with_version
, NULL
);
390 glCompileShader(g_FragHandle
);
391 CheckShader(g_FragHandle
, "fragment shader");
393 g_ShaderHandle
= glCreateProgram();
394 glAttachShader(g_ShaderHandle
, g_VertHandle
);
395 glAttachShader(g_ShaderHandle
, g_FragHandle
);
396 glLinkProgram(g_ShaderHandle
);
397 CheckProgram(g_ShaderHandle
, "shader program");
399 g_AttribLocationTex
= glGetUniformLocation(g_ShaderHandle
, "Texture");
400 g_AttribLocationProjMtx
= glGetUniformLocation(g_ShaderHandle
, "ProjMtx");
401 g_AttribLocationPosition
= glGetAttribLocation(g_ShaderHandle
, "Position");
402 g_AttribLocationUV
= glGetAttribLocation(g_ShaderHandle
, "UV");
403 g_AttribLocationColor
= glGetAttribLocation(g_ShaderHandle
, "Color");
406 glGenBuffers(1, &g_VboHandle
);
407 glGenBuffers(1, &g_ElementsHandle
);
409 ImGui_ImplOpenGL3_CreateFontsTexture();
411 // Restore modified GL state
412 glBindTexture(GL_TEXTURE_2D
, last_texture
);
413 glBindBuffer(GL_ARRAY_BUFFER
, last_array_buffer
);
414 glBindVertexArray(last_vertex_array
);
419 void ImGui_ImplOpenGL3_DestroyDeviceObjects()
421 if (g_VboHandle
) glDeleteBuffers(1, &g_VboHandle
);
422 if (g_ElementsHandle
) glDeleteBuffers(1, &g_ElementsHandle
);
423 g_VboHandle
= g_ElementsHandle
= 0;
425 if (g_ShaderHandle
&& g_VertHandle
) glDetachShader(g_ShaderHandle
, g_VertHandle
);
426 if (g_VertHandle
) glDeleteShader(g_VertHandle
);
429 if (g_ShaderHandle
&& g_FragHandle
) glDetachShader(g_ShaderHandle
, g_FragHandle
);
430 if (g_FragHandle
) glDeleteShader(g_FragHandle
);
433 if (g_ShaderHandle
) glDeleteProgram(g_ShaderHandle
);
436 ImGui_ImplOpenGL3_DestroyFontsTexture();