Implement gradient borders

2 files changed, 93 insertions, 0 deletions

diff --git a/src/render_helpers/shaders/gradient_border.frag b/src/render_helpers/shaders/gradient_border.frag
new file mode 100644
index 00000000..354968cf
--- /dev/null
+++ b/src/render_helpers/shaders/gradient_border.frag
@@ -0,0 +1,46 @@
+precision mediump float;
+uniform float alpha;
+#if defined(DEBUG_FLAGS)
+uniform float tint;
+#endif
+uniform vec2 size;
+varying vec2 v_coords;
+
+uniform vec4 color_from;
+uniform vec4 color_to;
+uniform float angle;
+uniform vec2 gradient_offset;
+uniform float gradient_width;
+uniform float gradient_total;
+
+#define FRAC_PI_2   1.57079632679
+#define PI          3.14159265359
+#define FRAC_3_PI_2 4.71238898038
+#define TAU         6.28318530718
+
+void main() {
+    vec2 coords = v_coords * size + gradient_offset;
+
+    if ((FRAC_PI_2 <= angle && angle < PI) || (FRAC_3_PI_2 <= angle && angle < TAU))
+        coords.x -= gradient_width;
+
+    float frag_angle = FRAC_PI_2;
+    if (coords.x != 0.0)
+        frag_angle = atan(coords.y, coords.x);
+
+    float angle_frag_to_grad = frag_angle - angle;
+
+    float frac = cos(angle_frag_to_grad) * length(coords) / gradient_total;
+    if (PI <= angle)
+        frac += 1.0;
+    frac = clamp(frac, 0.0, 1.0);
+
+    vec4 out_color = mix(color_from, color_to, frac);
+
+#if defined(DEBUG_FLAGS)
+    if (tint == 1.0)
+        out_color = vec4(0.0, 0.3, 0.0, 0.2) + out_color * 0.8;
+#endif
+
+    gl_FragColor = out_color;
+}
diff --git a/src/render_helpers/shaders/mod.rs b/src/render_helpers/shaders/mod.rs
new file mode 100644
index 00000000..72e9fa1c
--- /dev/null
+++ b/src/render_helpers/shaders/mod.rs
@@ -0,0 +1,47 @@
+use smithay::backend::renderer::gles::{GlesPixelProgram, GlesRenderer, UniformName, UniformType};
+
+use super::renderer::NiriRenderer;
+
+pub struct Shaders {
+    pub gradient_border: Option<GlesPixelProgram>,
+}
+
+impl Shaders {
+    fn compile(renderer: &mut GlesRenderer) -> Self {
+        let _span = tracy_client::span!("Shaders::compile");
+
+        let gradient_border = renderer
+            .compile_custom_pixel_shader(
+                include_str!("gradient_border.frag"),
+                &[
+                    UniformName::new("color_from", UniformType::_4f),
+                    UniformName::new("color_to", UniformType::_4f),
+                    UniformName::new("angle", UniformType::_1f),
+                    UniformName::new("gradient_offset", UniformType::_2f),
+                    UniformName::new("gradient_width", UniformType::_1f),
+                    UniformName::new("gradient_total", UniformType::_1f),
+                ],
+            )
+            .map_err(|err| {
+                warn!("error compiling gradient border shader: {err:?}");
+            })
+            .ok();
+
+        Self { gradient_border }
+    }
+
+    pub fn get(renderer: &mut impl NiriRenderer) -> &Self {
+        let renderer = renderer.as_gles_renderer();
+        let data = renderer.egl_context().user_data();
+        data.get()
+            .expect("shaders::init() must be called when creating the renderer")
+    }
+}
+
+pub fn init(renderer: &mut GlesRenderer) {
+    let shaders = Shaders::compile(renderer);
+    let data = renderer.egl_context().user_data();
+    if !data.insert_if_missing(|| shaders) {
+        error!("shaders were already compiled");
+    }
+}