RENDERING.md

Rendering in Renderlib

Forward Rendering

Forward rendering is the simplest rendering technique where each object is rendered in a single pass with lighting calculated in the fragment shader.

Mesh Data → Vertex Shader → Fragment Shader → Framebuffer

In renderlib:

• Used in forward.rs example
• Simple to implement
• Good for scenes with few light sources

Deferred Rendering

Deferred rendering separates geometry processing from lighting calculation using a G-buffer:

Phase 1 (Geometry Pass):
Mesh Data → Vertex Shader → Fragment Shader → G-Buffer (Position, Normal, Albedo)

Phase 2 (Lighting Pass):
Full-screen Quad → Sample G-Buffer → Calculate Lighting → Framebuffer

In renderlib:

• Used in deferred.rs and deferred_with_camera_controls.rs examples
• Uses [GBuffer] from the deferred module
• Efficient for scenes with many light sources
• More memory usage due to G-buffer storage

Custom Pipelines

Create custom rendering pipelines using [RenderPipelineBuilder] from device_helpers:

use renderlib::device_helpers::RenderPipelineBuilder;

let pipeline = RenderPipelineBuilder::new(device)
    .with_shader_module(shader_module)
    .with_vertex_entry("vs_main")
    .with_fragment_entry("fs_main")
    .with_vertex_buffers(vec![vertex_layout])
    .with_color_formats(vec![surface_format])
    .build()?;

Multiple Render Passes

For techniques like deferred rendering, use multiple render passes:

// Geometry pass
let mut geometry_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
    color_attachments: &gbuffer.color_attachments(),
    depth_stencil_attachment: Some(depth_attachment),
    ..Default::default()
});
// Draw meshes...

// Lighting pass
let mut lighting_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
    color_attachments: &[Some(output_attachment)],
    ..Default::default()
});
// Draw full-screen quad...

Performance Tips

• Minimize draw calls: Batch similar objects
• Reuse pipelines: Create pipelines once, reuse often
• Efficient buffers: Use appropriate buffer usages
• Depth testing: Enable for proper occlusion
• Shader hot-reload: Press 'R' to reload shaders during development