[FX Renderer] Add blur (#30)

* Initial blur implementation

* Added additional blur effects from SwayFX

* Simplified blur pass functions to match the other pass functions

* Minor fixes

* Added support for optimized blur

* tinywl: Don't set decoration values every frame

* Updated public blur function docs

* Simplified blur buffer management

* Moved ignore transparent bool into a per buffer option

* Clip the scene_buffer when blur is enabled

* Added back corner and shadow checks in opaque_region function

* Renamed fx_render_blur_options to fx_render_blur_pass_options

* Fixed nits

* Removed unused fx_framebuffer_bind_wlr_fbo function

* Removed wlr_scene impl. Should be moved into future PR instead

* Made blur impl independent of wlr_scene

* Moved shader init back into fx_renderer.c

* Renamed fx_framebuffer_get_or_create_bufferless to fx_framebuffer_get_or_create_custom

6 files changed, 115 insertions, 7 deletions

diff --git a/render/fx_renderer/gles2/shaders/blur1.frag b/render/fx_renderer/gles2/shaders/blur1.frag
new file mode 100644
index 0000000..e7cb1be
--- /dev/null
+++ b/render/fx_renderer/gles2/shaders/blur1.frag
@@ -0,0 +1,18 @@
+precision mediump float;
+varying mediump vec2 v_texcoord;
+uniform sampler2D tex;
+
+uniform float radius;
+uniform vec2 halfpixel;
+
+void main() {
+    vec2 uv = v_texcoord * 2.0;
+
+    vec4 sum = texture2D(tex, uv) * 4.0;
+    sum += texture2D(tex, uv - halfpixel.xy * radius);
+    sum += texture2D(tex, uv + halfpixel.xy * radius);
+    sum += texture2D(tex, uv + vec2(halfpixel.x, -halfpixel.y) * radius);
+    sum += texture2D(tex, uv - vec2(halfpixel.x, -halfpixel.y) * radius);
+
+    gl_FragColor = sum / 8.0;
+}
diff --git a/render/fx_renderer/gles2/shaders/blur2.frag b/render/fx_renderer/gles2/shaders/blur2.frag
new file mode 100644
index 0000000..3755a29
--- /dev/null
+++ b/render/fx_renderer/gles2/shaders/blur2.frag
@@ -0,0 +1,22 @@
+precision mediump float;
+varying mediump vec2 v_texcoord;
+uniform sampler2D tex;
+
+uniform float radius;
+uniform vec2 halfpixel;
+
+void main() {
+    vec2 uv = v_texcoord / 2.0;
+
+    vec4 sum = texture2D(tex, uv + vec2(-halfpixel.x * 2.0, 0.0) * radius);
+
+    sum += texture2D(tex, uv + vec2(-halfpixel.x, halfpixel.y) * radius) * 2.0;
+    sum += texture2D(tex, uv + vec2(0.0, halfpixel.y * 2.0) * radius);
+    sum += texture2D(tex, uv + vec2(halfpixel.x, halfpixel.y) * radius) * 2.0;
+    sum += texture2D(tex, uv + vec2(halfpixel.x * 2.0, 0.0) * radius);
+    sum += texture2D(tex, uv + vec2(halfpixel.x, -halfpixel.y) * radius) * 2.0;
+    sum += texture2D(tex, uv + vec2(0.0, -halfpixel.y * 2.0) * radius);
+    sum += texture2D(tex, uv + vec2(-halfpixel.x, -halfpixel.y) * radius) * 2.0;
+
+    gl_FragColor = sum / 12.0;
+}
diff --git a/render/fx_renderer/gles2/shaders/blur_effects.frag b/render/fx_renderer/gles2/shaders/blur_effects.frag
new file mode 100644
index 0000000..fcead5d
--- /dev/null
+++ b/render/fx_renderer/gles2/shaders/blur_effects.frag
@@ -0,0 +1,60 @@
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
+precision mediump float;
+#endif
+
+varying vec2 v_texcoord;
+
+uniform sampler2D tex;
+
+uniform float noise;
+uniform float brightness;
+uniform float contrast;
+uniform float saturation;
+
+mat4 brightnessMatrix() {
+	float b = brightness - 1.0;
+	return mat4(1, 0, 0, 0,
+				0, 1, 0, 0,
+				0, 0, 1, 0,
+				b, b, b, 1);
+}
+
+mat4 contrastMatrix() {
+	float t = (1.0 - contrast) / 2.0;
+	return mat4(contrast, 0, 0, 0,
+				0, contrast, 0, 0,
+				0, 0, contrast, 0,
+				t, t, t, 1);
+}
+
+mat4 saturationMatrix() {
+	vec3 luminance = vec3(0.3086, 0.6094, 0.0820);
+	float oneMinusSat = 1.0 - saturation;
+	vec3 red = vec3(luminance.x * oneMinusSat);
+	red+= vec3(saturation, 0, 0);
+	vec3 green = vec3(luminance.y * oneMinusSat);
+	green += vec3(0, saturation, 0);
+	vec3 blue = vec3(luminance.z * oneMinusSat);
+	blue += vec3(0, 0, saturation);
+	return mat4(red, 0,
+				green, 0,
+				blue, 0,
+				0, 0, 0, 1);
+}
+
+// Fast generative noise function
+float hash(vec2 p) {
+	return fract(sin(dot(p, vec2(12.9898, 78.233))) * 43758.5453);
+}
+
+void main() {
+	vec4 color = texture2D(tex, v_texcoord);
+	color *= brightnessMatrix() * contrastMatrix() * saturationMatrix();
+	float noiseHash = hash(v_texcoord);
+	float noiseAmount = (mod(noiseHash, 1.0) - 0.5);
+	color.rgb += noiseAmount * noise;
+
+	gl_FragColor = color;
+}
diff --git a/render/fx_renderer/gles2/shaders/meson.build b/render/fx_renderer/gles2/shaders/meson.build
index 42f066e..a751e1a 100644
--- a/render/fx_renderer/gles2/shaders/meson.build
+++ b/render/fx_renderer/gles2/shaders/meson.build
@@ -6,6 +6,9 @@ shaders = [
     'tex.frag',
     'box_shadow.frag',
     'stencil_mask.frag',
+    'blur1.frag',
+    'blur2.frag',
+    'blur_effects.frag',
 ]
 
 foreach name : shaders
diff --git a/render/fx_renderer/gles2/shaders/stencil_mask.frag b/render/fx_renderer/gles2/shaders/stencil_mask.frag
index 523adc8..e1fd76a 100644
--- a/render/fx_renderer/gles2/shaders/stencil_mask.frag
+++ b/render/fx_renderer/gles2/shaders/stencil_mask.frag
@@ -11,12 +11,12 @@ uniform vec2 position;
 uniform float radius;
 
 void main() {
-    vec2 q = abs(gl_FragCoord.xy - position - half_size) - half_size + radius;
-    float dist = min(max(q.x,q.y), 0.0) + length(max(q, 0.0)) - radius;
-    float smoothedAlpha = 1.0 - smoothstep(-1.0, 0.5, dist);
-    gl_FragColor = mix(vec4(0.0), vec4(1.0), smoothedAlpha);
+	vec2 q = abs(gl_FragCoord.xy - position - half_size) - half_size + radius;
+	float dist = min(max(q.x,q.y), 0.0) + length(max(q, 0.0)) - radius;
+	float smoothedAlpha = 1.0 - smoothstep(-1.0, 0.5, dist);
+	gl_FragColor = mix(vec4(0.0), vec4(1.0), smoothedAlpha);
 
-    if (gl_FragColor.a < 1.0) {
-        discard;
-    }
+	if (gl_FragColor.a < 1.0) {
+		discard;
+	}
 }
diff --git a/render/fx_renderer/gles2/shaders/tex.frag b/render/fx_renderer/gles2/shaders/tex.frag
index 8c14373..b7ba3fc 100644
--- a/render/fx_renderer/gles2/shaders/tex.frag
+++ b/render/fx_renderer/gles2/shaders/tex.frag
@@ -29,6 +29,7 @@ uniform float alpha;
 uniform vec2 size;
 uniform vec2 position;
 uniform float radius;
+uniform bool discard_transparent;
 
 vec4 sample_texture() {
 #if SOURCE == SOURCE_TEXTURE_RGBA || SOURCE == SOURCE_TEXTURE_EXTERNAL
@@ -46,4 +47,8 @@ void main() {
 		float smooth = smoothstep(-1.0, 0.5, d);
 		gl_FragColor = mix(vec4(0), gl_FragColor, smooth);
 	}
+
+	if (discard_transparent && gl_FragColor.a == 0.0) {
+		discard;
+	}
 }