dear-imgui-glow

Glow (OpenGL) renderer for Dear ImGui.

This crate provides a Glow-based renderer for Dear ImGui, allowing you to render Dear ImGui interfaces using the Glow OpenGL abstraction.

Features

• Basic rendering: Render Dear ImGui draw data using OpenGL
• Texture support: Handle font textures and user textures
• Multi-viewport support: Support for multiple windows (feature-gated)
• OpenGL compatibility: Support for OpenGL 2.1+ and OpenGL ES 2.0+
• Feature-gated optimizations: Optional support for various OpenGL features

Usage

Add this to your Cargo.toml:

[dependencies]
dear-imgui-glow = "0.1"

Basic Example

use dear_imgui::Context;
use dear_imgui_glow::GlowRenderer;
use glow::HasContext;

// Initialize your OpenGL context and Dear ImGui context
let gl = glow::Context::from_loader_function(|s| {
    // Your OpenGL loader function
    load_gl_function(s)
});
let mut imgui = Context::create();

// Create the renderer
let mut renderer = GlowRenderer::new(gl, &mut imgui)?;

// In your render loop:
imgui.new_frame();
// ... build your UI ...
let draw_data = imgui.render();
renderer.render(draw_data)?;

Advanced Usage

For more control, you can use the Renderer directly:

use dear_imgui_glow::{Renderer, SimpleTextureMap};

let mut texture_map = SimpleTextureMap::new();
let mut renderer = Renderer::new(&gl, &mut imgui, &mut texture_map)?;

// In your render loop:
renderer.render(&gl, &texture_map, draw_data)?;

Features

The following features are available:

• docking: Enable docking features (requires Dear ImGui docking branch)
• multi-viewport: Enable multi-viewport support
• gl_extensions_support: Enable checking for OpenGL extensions
• debug_message_insert_support: Support for gl.debug_message_insert
• bind_vertex_array_support: Support for glBindVertexArray
• vertex_offset_support: Support for glDrawElementsBaseVertex
• clip_origin_support: Support for GL_CLIP_ORIGIN
• bind_sampler_support: Support for glBindSampler
• polygon_mode_support: Support for glPolygonMode
• primitive_restart_support: Support for GL_PRIMITIVE_RESTART

All features except docking and multi-viewport are enabled by default.

OpenGL Compatibility

This renderer supports:

• Desktop OpenGL: 2.1+ (with full feature support on 3.2+)
• OpenGL ES: 2.0+ (with full feature support on 3.0+)
• WebGL: 1.0 and 2.0

Feature support is automatically detected based on the OpenGL version and available extensions.

Multi-Viewport Support

Multi-viewport support allows Dear ImGui to create additional windows outside the main application window. To enable this:

1. Enable the multi-viewport feature
2. Enable multi-viewport in Dear ImGui: io.config_flags |= ConfigFlags::VIEWPORTS_ENABLE
3. Handle platform events for additional windows

Implementation Status

✅ Completed Features:

• Core Rendering: Complete OpenGL renderer with glow backend
• Font Management: Font atlas texture creation and management
• Buffer Management: Vertex and index buffer handling with dynamic sizing
• State Management: Complete OpenGL state backup and restoration
• Shader System: Dynamic shader compilation with version detection
• Texture System: Texture mapping and ImGui texture update support
• Device Objects: Proper creation/destruction of OpenGL resources
• Frame Management: NewFrame functionality for resource recreation
• Multi-viewport: Basic multi-viewport callback structure (feature-gated)
• Version Support: OpenGL 2.1+, ES 2.0+, ES 3.0+ compatibility
• Feature Detection: Runtime OpenGL capability detection
• Projection Matrix: Proper orthographic projection with clip origin support
• GlowRenderer: Simplified high-level renderer interface

🚧 In Progress:

• Complete multi-viewport implementation with context management
• Example applications and tutorials
• Performance optimizations

📋 TODO:

• Add comprehensive examples and documentation
• Implement texture atlas updates for dynamic fonts
• Add more OpenGL state optimizations
• Performance profiling and improvements
• Integration tests

Architecture

The crate is structured as follows:

• renderer.rs - Main renderer implementation (Renderer and GlowRenderer)
• shaders.rs - Shader compilation and management
• state.rs - OpenGL state backup/restoration
• texture.rs - Texture management and mapping
• versions.rs - OpenGL version detection and feature support
• error.rs - Error types and handling

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.