render_helpers: Add GradientFadeTexture

2 files changed, 59 insertions, 0 deletions

diff --git a/src/render_helpers/shaders/gradient_fade.frag b/src/render_helpers/shaders/gradient_fade.frag
new file mode 100644
index 00000000..eccc7066
--- /dev/null
+++ b/src/render_helpers/shaders/gradient_fade.frag
@@ -0,0 +1,47 @@
+#version 100
+
+//_DEFINES_
+
+#if defined(EXTERNAL)
+#extension GL_OES_EGL_image_external : require
+#endif
+
+precision highp float;
+#if defined(EXTERNAL)
+uniform samplerExternalOES tex;
+#else
+uniform sampler2D tex;
+#endif
+
+uniform float alpha;
+varying vec2 v_coords;
+
+#if defined(DEBUG_FLAGS)
+uniform float tint;
+#endif
+
+// x is left edge, y is right edge of the gradient.
+uniform vec2 cutoff;
+
+void main() {
+    // Sample the texture.
+    vec4 color = texture2D(tex, v_coords);
+#if defined(NO_ALPHA)
+    color = vec4(color.rgb, 1.0);
+#endif
+
+    if (cutoff.x < cutoff.y) {
+        float fade = clamp((cutoff.y - v_coords.x) / (cutoff.y - cutoff.x), 0.0, 1.0);
+        color = color * fade;
+    }
+
+    // Apply final alpha and tint.
+    color = color * alpha;
+
+#if defined(DEBUG_FLAGS)
+    if (tint == 1.0)
+        color = vec4(0.0, 0.2, 0.0, 0.2) + color * 0.8;
+#endif
+
+    gl_FragColor = color;
+}
diff --git a/src/render_helpers/shaders/mod.rs b/src/render_helpers/shaders/mod.rs
index 2db00662..6fccce7f 100644
--- a/src/render_helpers/shaders/mod.rs
+++ b/src/render_helpers/shaders/mod.rs
@@ -14,6 +14,7 @@ pub struct Shaders {
     pub shadow: Option<ShaderProgram>,
     pub clipped_surface: Option<GlesTexProgram>,
     pub resize: Option<ShaderProgram>,
+    pub gradient_fade: Option<GlesTexProgram>,
     pub custom_resize: RefCell<Option<ShaderProgram>>,
     pub custom_close: RefCell<Option<ShaderProgram>>,
     pub custom_open: RefCell<Option<ShaderProgram>>,
@@ -96,11 +97,22 @@ impl Shaders {
             })
             .ok();
 
+        let gradient_fade = renderer
+            .compile_custom_texture_shader(
+                include_str!("gradient_fade.frag"),
+                &[UniformName::new("cutoff", UniformType::_2f)],
+            )
+            .map_err(|err| {
+                warn!("error compiling gradient fade shader: {err:?}");
+            })
+            .ok();
+
         Self {
             border,
             shadow,
             clipped_surface,
             resize,
+            gradient_fade,
             custom_resize: RefCell::new(None),
             custom_close: RefCell::new(None),
             custom_open: RefCell::new(None),