Migrate vertex-instancing.

examples/common/src/instancing-fs.glsl

@@ -0,0 +1,12 @@
+in vec3 v_color;
+in float v_instance_bias;
+
+out vec4 frag;
+
+uniform float t;
+
+void main() {
+  float q = v_instance_bias * 10. + t;
+  frag = vec4(v_color * vec3(pow(cos(q), 2.), pow(sin(q), 2.), cos(q * .5)), 1.);
+  frag = pow(frag, vec4(1./2.2));
+}

examples/common/src/instancing-vs.glsl

@@ -0,0 +1,13 @@
+in vec2 co;
+in vec3 color;
+in vec2 position;
+in float weight;
+
+out vec3 v_color;
+out float v_instance_bias;
+
+void main() {
+  gl_Position = vec4(co * weight + position, 0., 1.);
+  v_color = color;
+  v_instance_bias = float(gl_InstanceID);
+}

examples/common/src/lib.rs

@@ -36,6 +36,7 @@ pub mod shader_uniforms;
 pub mod shared;
 pub mod sliced_tess;
 pub mod texture;
+pub mod vertex_instancing;
 
 /// Example interface.
 pub trait Example: Sized {

examples/common/src/vertex_instancing.rs

@@ -0,0 +1,138 @@
+//! This program shows you how to do *vertex instancing*, the easy way.
+//!
+//! Press <escape> to quit or close the window.
+//!
+//! https://docs.rs/luminance
+
+use crate::{
+  shared::{
+    Instance, Semantics, Vertex, VertexColor, VertexInstancePosition, VertexPosition, VertexWeight,
+  },
+  Example, InputAction, LoopFeedback, PlatformServices,
+};
+use luminance::context::GraphicsContext;
+use luminance_front::{
+  framebuffer::Framebuffer,
+  pipeline::PipelineState,
+  render_state::RenderState,
+  shader::Program,
+  tess::{Mode, Tess},
+  texture::Dim2,
+  Backend,
+};
+
+const VS: &'static str = include_str!("instancing-vs.glsl");
+const FS: &'static str = include_str!("instancing-fs.glsl");
+
+// Only one triangle this time.
+const TRI_VERTICES: [Vertex; 3] = [
+  Vertex {
+    pos: VertexPosition::new([0.5, -0.5]),
+    rgb: VertexColor::new([1., 0., 0.]),
+  },
+  Vertex {
+    pos: VertexPosition::new([0.0, 0.5]),
+    rgb: VertexColor::new([0., 1., 0.]),
+  },
+  Vertex {
+    pos: VertexPosition::new([-0.5, -0.5]),
+    rgb: VertexColor::new([0., 0., 1.]),
+  },
+];
+
+// Instances. We’ll be using five triangles.
+const INSTANCES: [Instance; 5] = [
+  Instance {
+    pos: VertexInstancePosition::new([0., 0.]),
+    w: VertexWeight::new(0.1),
+  },
+  Instance {
+    pos: VertexInstancePosition::new([-0.5, 0.5]),
+    w: VertexWeight::new(0.5),
+  },
+  Instance {
+    pos: VertexInstancePosition::new([-0.25, -0.1]),
+    w: VertexWeight::new(0.1),
+  },
+  Instance {
+    pos: VertexInstancePosition::new([0.45, 0.25]),
+    w: VertexWeight::new(0.75),
+  },
+  Instance {
+    pos: VertexInstancePosition::new([0.6, -0.3]),
+    w: VertexWeight::new(0.3),
+  },
+];
+
+pub struct LocalExample {
+  program: Program<Semantics, (), ()>,
+  triangle: Tess<Vertex, (), Instance>,
+}
+
+impl Example for LocalExample {
+  fn bootstrap(
+    _: &mut impl PlatformServices,
+    context: &mut impl GraphicsContext<Backend = Backend>,
+  ) -> Self {
+    // notice that we don’t set a uniform interface here: we’re going to look it up on the fly
+    let program = context
+      .new_shader_program::<Semantics, (), ()>()
+      .from_strings(VS, None, None, FS)
+      .expect("program creation")
+      .ignore_warnings();
+
+    let triangle = context
+      .new_tess()
+      .set_vertices(&TRI_VERTICES[..])
+      .set_instances(&INSTANCES[..])
+      .set_mode(Mode::Triangle)
+      .build()
+      .unwrap();
+
+    Self { program, triangle }
+  }
+
+  fn render_frame(
+    mut self,
+    t: f32,
+    back_buffer: Framebuffer<Dim2, (), ()>,
+    actions: impl Iterator<Item = InputAction>,
+    context: &mut impl GraphicsContext<Backend = Backend>,
+  ) -> LoopFeedback<Self> {
+    for action in actions {
+      match action {
+        InputAction::Quit => return LoopFeedback::Exit,
+
+        _ => (),
+      }
+    }
+
+    let program = &mut self.program;
+    let triangle = &self.triangle;
+
+    let render = context
+      .new_pipeline_gate()
+      .pipeline(
+        &back_buffer,
+        &PipelineState::default(),
+        |_, mut shd_gate| {
+          shd_gate.shade(program, |mut iface, _, mut rdr_gate| {
+            if let Ok(ref time_u) = iface.query().unwrap().ask("t") {
+              iface.set(time_u, t);
+            }
+
+            rdr_gate.render(&RenderState::default(), |mut tess_gate| {
+              tess_gate.render(triangle)
+            })
+          })
+        },
+      )
+      .assume();
+
+    if render.is_ok() {
+      LoopFeedback::Continue(self)
+    } else {
+      LoopFeedback::Exit
+    }
+  }
+}

examples/desktop/src/main.rs

@@ -131,7 +131,8 @@ examples! {
   "texture", texture,
   "offscreen", offscreen,
   "shader-uniform-adapt", shader_uniform_adapt,
-  "dynamic-uniform-interface", dynamic_uniform_interface
+  "dynamic-uniform-interface", dynamic_uniform_interface,
+  "vertex-instancing", vertex_instancing
 }
 
 fn main() {

examples/web/src/lib.rs

@@ -174,7 +174,8 @@ examples! {
   "texture", texture,
   "offscreen", offscreen,
   "shader-uniform-adapt", shader_uniform_adapt,
-  "dynamic-uniform-interface", dynamic_uniform_interface
+  "dynamic-uniform-interface", dynamic_uniform_interface,
+  "vertex-instancing", vertex_instancing
 }
 
 #[wasm_bindgen]