Tech ENABLE_GL_IMGUI_SHADERS - Render imgui using shaders

(cherry picked from commit prusa3d/PrusaSlicer@d0d89a4d5b)

resources/shaders/imgui.fs

@@ -0,0 +1,11 @@
+#version 110
+
+uniform sampler2D Texture;
+
+varying vec2 Frag_UV;
+varying vec4 Frag_Color;
+
+void main()
+{
+	gl_FragColor = Frag_Color * texture2D(Texture, Frag_UV.st);
+}

resources/shaders/imgui.vs

@@ -0,0 +1,17 @@
+#version 110
+
+uniform mat4 ProjMtx;
+
+attribute vec2 Position;
+attribute vec2 UV;
+attribute vec4 Color;
+
+varying vec2 Frag_UV;
+varying vec4 Frag_Color;
+
+void main()
+{
+	Frag_UV = UV;
+	Frag_Color = Color;
+    gl_Position = ProjMtx * vec4(Position.xy, 0.0, 1.0);
+}

src/slic3r/GUI/GLShader.cpp

@@ -122,8 +122,7 @@ bool GLShaderProgram::init_from_texts(const std::string& name, const ShaderSourc
 
     for (size_t i = 0; i < static_cast<size_t>(EShaderType::Count); ++i) {
         const std::string& source = sources[i];
-        if (!source.empty())
+        if (!source.empty()) {
-        {
             EShaderType type = static_cast<EShaderType>(i);
             auto [result, id] = create_shader(type);
             if (result)
@@ -301,6 +300,17 @@ void GLShaderProgram::set_uniform(int id, const Matrix3d& value) const
     set_uniform(id, (Matrix3f)value.cast<float>());
 }
 
+void GLShaderProgram::set_uniform(int id, const Matrix4f& value) const
+{
+    if (id >= 0)
+        glsafe(::glUniformMatrix4fv(id, 1, GL_FALSE, static_cast<const GLfloat*>(value.data())));
+}
+
+void GLShaderProgram::set_uniform(int id, const Matrix4d& value) const
+{
+    set_uniform(id, (Matrix4f)value.cast<float>());
+}
+
 void GLShaderProgram::set_uniform(int id, const Vec3f& value) const
 {
     if (id >= 0)

src/slic3r/GUI/GLShader.hpp

@@ -11,6 +11,7 @@ namespace Slic3r {
 
 class ColorRGB;
 class ColorRGBA;
+
 class GLShaderProgram
 {
 public:
@@ -61,6 +62,8 @@ public:
     void set_uniform(const char* name, const Transform3d& value) const { set_uniform(get_uniform_location(name), value); }
     void set_uniform(const char* name, const Matrix3f& value) const { set_uniform(get_uniform_location(name), value); }
     void set_uniform(const char* name, const Matrix3d& value) const { set_uniform(get_uniform_location(name), value); }
+    void set_uniform(const char* name, const Matrix4f& value) const { set_uniform(get_uniform_location(name), value); }
+    void set_uniform(const char* name, const Matrix4d& value) const { set_uniform(get_uniform_location(name), value); }
     void set_uniform(const char* name, const Vec3f& value) const { set_uniform(get_uniform_location(name), value); }
     void set_uniform(const char* name, const Vec3d& value) const { set_uniform(get_uniform_location(name), value); }
     void set_uniform(const char* name, const ColorRGB& value) const { set_uniform(get_uniform_location(name), value); }
@@ -81,6 +84,8 @@ public:
     void set_uniform(int id, const Transform3d& value) const;
     void set_uniform(int id, const Matrix3f& value) const;
     void set_uniform(int id, const Matrix3d& value) const;
+    void set_uniform(int id, const Matrix4f& value) const;
+    void set_uniform(int id, const Matrix4d& value) const;
     void set_uniform(int id, const Vec3f& value) const;
     void set_uniform(int id, const Vec3d& value) const;
     void set_uniform(int id, const ColorRGB& value) const;

src/slic3r/GUI/GLShadersManager.cpp

@@ -33,6 +33,8 @@ std::pair<bool, std::string> GLShadersManager::init()
 
     bool valid = true;
 
+    // imgui shader
+    valid &= append_shader("imgui", { "imgui.vs", "imgui.fs" });
     // basic shader, used to render all what was previously rendered using the immediate mode
     valid &= append_shader("flat_attr", { "flat_attr.vs", "flat.fs" });
     // basic shader for textures, used to render textures

src/slic3r/GUI/ImGuiWrapper.cpp

@@ -29,13 +29,16 @@
 #include "libslic3r/Utils.hpp"
 #include "libslic3r/Color.hpp"
 #include "libslic3r/Shape/TextShape.hpp"
+
 #include "3DScene.hpp"
 #include "GUI.hpp"
 #include "I18N.hpp"
 #include "Search.hpp"
 #include "BitmapCache.hpp"
+#include "GUI_App.hpp"
 
 #include "../Utils/MacDarkMode.hpp"
+
 #include "nanosvg/nanosvg.h"
 #include "nanosvg/nanosvgrast.h"
 #include "OpenGLManager.hpp"
@@ -2386,13 +2389,25 @@ void ImGuiWrapper::init_style()
 
 void ImGuiWrapper::render_draw_data(ImDrawData *draw_data)
 {
+    if (draw_data == nullptr || draw_data->CmdListsCount == 0)
+        return;
+
+    GLShaderProgram* shader = wxGetApp().get_shader("imgui");
+    if (shader == nullptr)
+        return;
+
     // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
     ImGuiIO& io = ImGui::GetIO();
-    const int fb_width = (int)(draw_data->DisplaySize.x * io.DisplayFramebufferScale.x);
+    const int fb_width  = (int)(draw_data->DisplaySize.x * io.DisplayFramebufferScale.x);
     const int fb_height = (int)(draw_data->DisplaySize.y * io.DisplayFramebufferScale.y);
     if (fb_width == 0 || fb_height == 0)
         return;
-    draw_data->ScaleClipRects(io.DisplayFramebufferScale);
+
+    GLShaderProgram* curr_shader = wxGetApp().get_current_shader();
+    if (curr_shader != nullptr)
+        curr_shader->stop_using();
+
+    shader->start_using();
 
     // We are using the OpenGL fixed pipeline to make the example code simpler to read!
     // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill.
@@ -2400,45 +2415,72 @@ void ImGuiWrapper::render_draw_data(ImDrawData *draw_data)
     GLint last_polygon_mode[2]; glsafe(::glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode));
     GLint last_viewport[4]; glsafe(::glGetIntegerv(GL_VIEWPORT, last_viewport));
     GLint last_scissor_box[4]; glsafe(::glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box));
+    GLint last_texture_env_mode; glsafe(::glGetTexEnviv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, &last_texture_env_mode));
     glsafe(::glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT));
     glsafe(::glEnable(GL_BLEND));
     glsafe(::glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA));
     glsafe(::glDisable(GL_CULL_FACE));
     glsafe(::glDisable(GL_DEPTH_TEST));
-    glsafe(::glDisable(GL_LIGHTING));
-    glsafe(::glDisable(GL_COLOR_MATERIAL));
     glsafe(::glEnable(GL_SCISSOR_TEST));
-    glsafe(::glEnableClientState(GL_VERTEX_ARRAY));
-    glsafe(::glEnableClientState(GL_TEXTURE_COORD_ARRAY));
-    glsafe(::glEnableClientState(GL_COLOR_ARRAY));
     glsafe(::glEnable(GL_TEXTURE_2D));
     glsafe(::glPolygonMode(GL_FRONT_AND_BACK, GL_FILL));
     glsafe(::glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE));
-    GLint texture_env_mode = GL_MODULATE;
-    glsafe(::glGetTexEnviv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, &texture_env_mode));
-    glsafe(::glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE));
-    //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
 
     // 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.
+    // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
     glsafe(::glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height));
-    glsafe(::glMatrixMode(GL_PROJECTION));
+    const float L = draw_data->DisplayPos.x;
-    glsafe(::glPushMatrix());
+    const float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
-    glsafe(::glLoadIdentity());
+    const float T = draw_data->DisplayPos.y;
-    glsafe(::glOrtho(draw_data->DisplayPos.x, draw_data->DisplayPos.x + draw_data->DisplaySize.x, draw_data->DisplayPos.y + draw_data->DisplaySize.y, draw_data->DisplayPos.y, -1.0f, +1.0f));
+    const float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
-    glsafe(::glMatrixMode(GL_MODELVIEW));
+
-    glsafe(::glPushMatrix());
+    Matrix4f ortho_projection;
-    glsafe(::glLoadIdentity());
+    ortho_projection <<
+        2.0f / (R - L), 0.0f,           0.0f,  (R + L) / (L - R),
+        0.0f,           2.0f / (T - B), 0.0f,  (T + B) / (B - T),
+        0.0f,           0.0f,           -1.0f, 0.0f,
+        0.0f,           0.0f,           0.0f,  1.0f;
+
+    shader->set_uniform("Texture", 0);
+    shader->set_uniform("ProjMtx", ortho_projection);
+
+    // Will project scissor/clipping rectangles into framebuffer space
+    const ImVec2 clip_off   = draw_data->DisplayPos;         // (0,0) unless using multi-viewports
+    const ImVec2 clip_scale = draw_data->FramebufferScale; // (1,1) unless using retina display which are often (2,2)
 
     // Render command lists
-    ImVec2 pos = draw_data->DisplayPos;
     for (int n = 0; n < draw_data->CmdListsCount; ++n) {
         const ImDrawList* cmd_list = draw_data->CmdLists[n];
         const ImDrawVert* vtx_buffer = cmd_list->VtxBuffer.Data;
         const ImDrawIdx* idx_buffer = cmd_list->IdxBuffer.Data;
-        glsafe(::glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, pos))));
+        const GLsizeiptr vtx_buffer_size = (GLsizeiptr)cmd_list->VtxBuffer.Size * (int)sizeof(ImDrawVert);
-        glsafe(::glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, uv))));
+        const GLsizeiptr idx_buffer_size = (GLsizeiptr)cmd_list->IdxBuffer.Size * (int)sizeof(ImDrawIdx);
-        glsafe(::glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, col))));
+
+        GLuint vbo_id;
+        glsafe(::glGenBuffers(1, &vbo_id));
+        glsafe(::glBindBuffer(GL_ARRAY_BUFFER, vbo_id));
+        glsafe(::glBufferData(GL_ARRAY_BUFFER, vtx_buffer_size, vtx_buffer, GL_STATIC_DRAW));
+
+        GLuint ibo_id;
+        glsafe(::glGenBuffers(1, &ibo_id));
+        glsafe(::glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo_id));
+        glsafe(::glBufferData(GL_ELEMENT_ARRAY_BUFFER, idx_buffer_size, idx_buffer, GL_STATIC_DRAW));
+
+        const int position_id = shader->get_attrib_location("Position");
+        if (position_id != -1) {
+            glsafe(::glVertexAttribPointer(position_id, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, pos)));
+            glsafe(::glEnableVertexAttribArray(position_id));
+        }
+        const int uv_id = shader->get_attrib_location("UV");
+        if (uv_id != -1) {
+            glsafe(::glVertexAttribPointer(uv_id, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, uv)));
+            glsafe(::glEnableVertexAttribArray(uv_id));
+        }
+        const int color_id = shader->get_attrib_location("Color");
+        if (color_id != -1) {
+            glsafe(::glVertexAttribPointer(color_id, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, col)));
+            glsafe(::glEnableVertexAttribArray(color_id));
+        }
 
         for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; ++cmd_i) {
             const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
@@ -2446,34 +2488,46 @@ void ImGuiWrapper::render_draw_data(ImDrawData *draw_data)
                 // 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);
+                // Project scissor/clipping rectangles into framebuffer space
-                if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f) {
+                const ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y);
-                    // Apply scissor/clipping rectangle
+                const ImVec2 clip_max((pcmd->ClipRect.z - clip_off.x) * clip_scale.x, (pcmd->ClipRect.w - clip_off.y) * clip_scale.y);
-                    glsafe(::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)));
+                if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y)
+                    continue;
 
-                    // Bind texture, Draw
+                // Apply scissor/clipping rectangle (Y is inverted in OpenGL)
-                    glsafe(::glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->TextureId));
+                glsafe(::glScissor((int)clip_min.x, (int)(fb_height - clip_max.y), (int)(clip_max.x - clip_min.x), (int)(clip_max.y - clip_min.y)));
-                    glsafe(::glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer));
+
-                }
+                // Bind texture, Draw
+                glsafe(::glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->GetTexID()));
+                glsafe(::glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, (void*)(intptr_t)(pcmd->IdxOffset * sizeof(ImDrawIdx))));
             }
             idx_buffer += pcmd->ElemCount;
         }
+
+        if (position_id != -1)
+            glsafe(::glDisableVertexAttribArray(position_id));
+        if (uv_id != -1)
+            glsafe(::glDisableVertexAttribArray(uv_id));
+        if (color_id != -1)
+            glsafe(::glDisableVertexAttribArray(color_id));
+
+        glsafe(::glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0));
+        glsafe(::glBindBuffer(GL_ARRAY_BUFFER, 0));
+
+        glsafe(::glDeleteBuffers(1, &ibo_id));
+        glsafe(::glDeleteBuffers(1, &vbo_id));
     }
 
     // Restore modified state
-    glsafe(::glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, texture_env_mode));
+    glsafe(::glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, last_texture_env_mode));
-    glsafe(::glDisableClientState(GL_COLOR_ARRAY));
-    glsafe(::glDisableClientState(GL_TEXTURE_COORD_ARRAY));
-    glsafe(::glDisableClientState(GL_VERTEX_ARRAY));
     glsafe(::glBindTexture(GL_TEXTURE_2D, (GLuint)last_texture));
-    glsafe(::glMatrixMode(GL_MODELVIEW));
-    glsafe(::glPopMatrix());
-    glsafe(::glMatrixMode(GL_PROJECTION));
-    glsafe(::glPopMatrix());
     glsafe(::glPopAttrib());
     glsafe(::glPolygonMode(GL_FRONT, (GLenum)last_polygon_mode[0]); glPolygonMode(GL_BACK, (GLenum)last_polygon_mode[1]));
     glsafe(::glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]));
     glsafe(::glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]));
+
+    if (curr_shader != nullptr)
+        curr_shader->start_using();
 }
 
 bool ImGuiWrapper::display_initialized() const