Improve rasterization rendering and add LCD rasterization (with subpixels).

app/qml/ApplicationSettings.qml

@@ -104,6 +104,7 @@ QtObject {
     readonly property int no_rasterization: 0
     readonly property int scanline_rasterization: 1
     readonly property int pixel_rasterization: 2
+    readonly property int lcd_rasterization: 3
 
     property int rasterization: no_rasterization
 
@@ -145,6 +146,13 @@ QtObject {
                     target: fontManager
                     source: "FontPixels.qml"
                 }
+            },
+            State {
+                when: rasterization == lcd_rasterization
+                PropertyChanges {
+                    target: fontManager
+                    source: "FontPixels.qml"
+                }
             }
         ]
 

app/qml/BurnInEffect.qml

@@ -89,6 +89,10 @@ Loader {
             }
         }
 
+        ShaderLibrary {
+            id: shaderLibrary
+        }
+
         ShaderEffect {
             id: burnInShaderEffect
 
@@ -118,9 +122,7 @@ Loader {
 
                  uniform highp float prevLastUpdate;" +
 
-                "float rgb2grey(vec3 v){
+                shaderLibrary.rgb2grey +
-                    return dot(v, vec3(0.21, 0.72, 0.04));
-                }" +
 
                 "void main() {
                     vec2 coords = qt_TexCoord0;

app/qml/NewTerminalFrame.qml

@@ -34,6 +34,10 @@ ShaderEffect {
 
     property size aadelta: Qt.size(1.0 / width, 1.0 / height)
 
+    ShaderLibrary {
+        id: shaderLibrary
+    }
+
     fragmentShader: "
         #ifdef GL_ES
             precision mediump float;
@@ -52,22 +56,14 @@ ShaderEffect {
             float dist = dot(cc, cc) * screenCurvature;
             return (coords + cc * (1.0 + dist) * dist);
         }
+        " +
 
-        float max2(vec2 v) {
+        shaderLibrary.max2 +
-            return max(v.x, v.y);
+        shaderLibrary.min2 +
-        }
+        shaderLibrary.prod2 +
+        shaderLibrary.sum2 +
 
-        float min2(vec2 v) {
+        "
-            return min(v.x, v.y);
-        }
-
-        float prod2(vec2 v) {
-            return v.x * v.y;
-        }
-
-        float sum2(vec2 v) {
-            return v.x + v.y;
-        }
 
         void main(){
             vec2 staticCoords = qt_TexCoord0;

app/qml/SettingsTerminalTab.qml

@@ -41,7 +41,7 @@ ColumnLayout {
                 property string selectedElement: model[currentIndex]
 
                 Layout.fillWidth: true
-                model: [qsTr("Default"), qsTr("Scanlines"), qsTr("Pixels")]
+                model: [qsTr("Default"), qsTr("Scanlines"), qsTr("Pixels"), qsTr("LCD")]
                 currentIndex: appSettings.rasterization
                 onCurrentIndexChanged: {
                     appSettings.rasterization = currentIndex

app/qml/ShaderLibrary.qml

@@ -0,0 +1,88 @@
+import QtQuick 2.0
+
+QtObject {
+    property string rasterizationShader:
+        (appSettings.rasterization === appSettings.no_rasterization ? "
+            lowp vec3 applyRasterization(vec2 screenCoords, lowp vec3 texel, vec2 virtualResolution, float intensity) {
+                return texel;
+            }" : "") +
+
+        (appSettings.rasterization === appSettings.scanline_rasterization ? "
+            #define INTENSITY 0.30
+            #define BRIGHTBOOST 0.30
+
+            lowp vec3 applyRasterization(vec2 screenCoords, lowp vec3 texel, vec2 virtualResolution, float intensity) {
+                lowp vec3 result = texel;
+
+                lowp vec3 pixelHigh = ((1.0 + BRIGHTBOOST) - (0.2 * texel)) * texel;
+                lowp vec3 pixelLow  = ((1.0 - INTENSITY) + (0.1 * texel)) * texel;
+
+                vec2 coords = fract(screenCoords * virtualResolution) * 2.0 - vec2(1.0);
+                lowp float mask = 1.0 - abs(coords.y);
+
+                lowp vec3 rasterizationColor = mix(pixelLow, pixelHigh, mask);
+                return mix(texel, rasterizationColor, intensity);
+            }" : "") +
+
+        (appSettings.rasterization === appSettings.pixel_rasterization ? "
+            #define INTENSITY 0.30
+            #define BRIGHTBOOST 0.30
+
+            lowp vec3 applyRasterization(vec2 screenCoords, lowp vec3 texel, vec2 virtualResolution, float intensity) {
+                lowp vec3 result = texel;
+
+                lowp vec3 pixelHigh = ((1.0 + BRIGHTBOOST) - (0.2 * texel)) * texel;
+                lowp vec3 pixelLow  = ((1.0 - INTENSITY) + (0.1 * texel)) * texel;
+
+                vec2 coords = fract(screenCoords * virtualResolution) * 2.0 - vec2(1.0);
+                coords = coords * coords;
+                lowp float mask = 1.0 - coords.x - coords.y;
+
+                lowp vec3 rasterizationColor = mix(pixelLow, pixelHigh, mask);
+                return mix(texel, rasterizationColor, intensity);
+            }" : "") +
+
+        (appSettings.rasterization === appSettings.lcd_rasterization ? "
+            #define brighten_scanlines 16.0
+            #define brighten_lcd 4.0
+            const vec3 offsets = vec3(3.141592654) * vec3(1.0/2.0,1.0/2.0 - 2.0/3.0,1.0/2.0-4.0/3.0);
+
+            lowp vec3 applyRasterization(vec2 screenCoords, lowp vec3 texel, vec2 virtualResolution, float intensity) {
+                vec2 omega = vec2(3.141592654) * vec2(2.0) * virtualResolution;
+
+                vec2 angle = screenCoords * omega;
+
+                float yfactor = (brighten_scanlines + sin(angle.y)) / (brighten_scanlines + 1.0);
+                vec3 xfactors = (brighten_lcd + sin(angle.x + offsets)) / (brighten_lcd + 1.0);
+
+                lowp vec3 rasterizationColor = yfactor * xfactors * texel;
+                return mix(texel, rasterizationColor, intensity);
+            }" : "") +
+
+        "\n\n"
+
+    property string min2: "
+        float min2(vec2 v) {
+            return min(v.x, v.y);
+        }\n\n"
+
+    property string rgb2grey: "
+        float rgb2grey(vec3 v) {
+            return dot(v, vec3(0.21, 0.72, 0.04));
+        }\n\n"
+
+    property string max2: "
+        float max2(vec2 v) {
+            return max(v.x, v.y);
+        }\n\n"
+
+    property string prod2: "
+        float prod2(vec2 v) {
+            return v.x * v.y;
+        }\n\n"
+
+    property string sum2: "
+        float sum2(vec2 v) {
+            return v.x + v.y;
+        }\n\n"
+}

app/qml/ShaderTerminal.qml

@@ -38,11 +38,19 @@ Item {
 
     property real ambientLight: appSettings.ambientLight * 0.2
 
-    property size virtual_resolution
+    property size virtualResolution
+    property size screenResolution
+
+    property real _screenDensity: Math.min(
+        screenResolution.width / virtualResolution.width,
+        screenResolution.height / virtualResolution.height
+    )
 
      ShaderEffect {
          id: dynamicShader
 
+         property ShaderLibrary shaderLibrary: ShaderLibrary { }
+
          property ShaderEffectSource screenBuffer: frameBuffer
          property ShaderEffectSource burnInSource: burnInEffect.source
          property ShaderEffectSource frameSource: terminalFrameLoader.item
@@ -74,7 +82,11 @@ Item {
          property size scaleNoiseSize: Qt.size((width) / (noiseTexture.width * appSettings.windowScaling * appSettings.totalFontScaling),
                                                (height) / (noiseTexture.height * appSettings.windowScaling * appSettings.totalFontScaling))
 
-         property size virtual_resolution: parent.virtual_resolution
+         property size virtualResolution: parent.virtualResolution
+
+         // Rasterization might display oversamping issues if virtual resolution is close to physical display resolution.
+         // We progressively disable rasterization from 4x up to 2x resolution.
+         property real rasterizationIntensity: Utils.smoothstep(2.0, 4.0, _screenDensity)
 
          property real time: timeManager.time
          property ShaderEffectSource noiseSource: noiseShaderSource
@@ -164,7 +176,8 @@ Item {
              uniform highp vec4 backgroundColor;
              uniform lowp float shadowLength;
 
-             uniform highp vec2 virtual_resolution;" +
+             uniform highp vec2 virtualResolution;
+             uniform lowp float rasterizationIntensity;\n" +
 
              (burnIn !== 0 ? "
                  uniform sampler2D burnInSource;
@@ -174,8 +187,7 @@ Item {
                  uniform sampler2D slowBurnInSource;" : "") +
              (staticNoise !== 0 ? "
                  uniform highp float staticNoise;" : "") +
-             (((staticNoise !== 0 || jitter !== 0)
+             (((staticNoise !== 0 || jitter !== 0) ||(fallBack && (flickering || horizontalSync))) ? "
-               ||(fallBack && (flickering || horizontalSync))) ? "
                  uniform lowp sampler2D noiseSource;
                  uniform highp vec2 scaleNoiseSize;" : "") +
              (screenCurvature !== 0 ? "
@@ -203,17 +215,14 @@ Item {
 
              (glowingLine !== 0 ? "
                  float randomPass(vec2 coords){
-                     return fract(smoothstep(-120.0, 0.0, coords.y - (virtual_resolution.y + 120.0) * fract(time * 0.00015)));
+                     return fract(smoothstep(-120.0, 0.0, coords.y - (virtualResolution.y + 120.0) * fract(time * 0.00015)));
                  }" : "") +
 
-             "float min2(vec2 v) {
+             shaderLibrary.min2 +
-                 return min(v.x, v.y);
+             shaderLibrary.rgb2grey +
-             }
+             shaderLibrary.rasterizationShader +
-
-             float rgb2grey(vec3 v){
-                 return dot(v, vec3(0.21, 0.72, 0.04));
-             }
 
+             "
              float isInScreen(vec2 v) {
                  return min2(step(0.0, v) - step(1.0, v));
              }
@@ -291,7 +300,7 @@ Item {
                      color += noiseVal * noise * (1.0 - distance * 1.3);" : "") +
 
                  (glowingLine !== 0 ? "
-                     color += randomPass(coords * virtual_resolution) * glowingLine;" : "") +
+                     color += randomPass(coords * virtualResolution) * glowingLine;" : "") +
 
                  "vec3 txt_color = texture2D(screenBuffer, txt_coords).rgb;" +
 
@@ -309,6 +318,8 @@ Item {
 
                   "txt_color += fontColor.rgb * vec3(color);" +
 
+                  "txt_color = applyRasterization(staticCoords, txt_color, virtualResolution, rasterizationIntensity);\n" +
+
                  "vec3 finalColor = txt_color;" +
 
                  (flickering !== 0 ? "
@@ -360,6 +371,10 @@ Item {
          }
      }
 
+     ShaderLibrary {
+         id: shaderLibrary
+     }
+
      ShaderEffect {
          id: staticShader
 
@@ -385,7 +400,7 @@ Item {
 
          property real ambientLight: parent.ambientLight
 
-         property size virtual_resolution: parent.virtual_resolution
+         property size virtualResolution: parent.virtualResolution
 
          blending: false
          visible: false
@@ -408,7 +423,7 @@ Item {
              uniform highp vec4 backgroundColor;
              uniform lowp float screen_brightness;
 
-             uniform highp vec2 virtual_resolution;" +
+             uniform highp vec2 virtualResolution;" +
 
              (bloom !== 0 ? "
                  uniform highp sampler2D bloomSource;
@@ -426,25 +441,7 @@ Item {
              (ambientLight !== 0 ? "
                  uniform lowp float ambientLight;" : "") +
 
-             "highp float getScanlineIntensity(vec2 coords) {
+             "
-                 float result = 1.0;" +
-
-                (appSettings.rasterization != appSettings.no_rasterization ?
-                    "float val = 0.0;
-                     vec2 rasterizationCoords = fract(coords * virtual_resolution);
-                     val += smoothstep(0.0, 0.5, rasterizationCoords.y);
-                     val -= smoothstep(0.5, 1.0, rasterizationCoords.y);
-                     result *= mix(0.5, 1.0, val);" : "") +
-
-                (appSettings.rasterization == appSettings.pixel_rasterization ?
-                    "val = 0.0;
-                     val += smoothstep(0.0, 0.5, rasterizationCoords.x);
-                     val -= smoothstep(0.5, 1.0, rasterizationCoords.x);
-                     result *= mix(0.5, 1.0, val);" : "") + "
-
-                return result;
-             }
-
              float min2(vec2 v) {
                  return min(v.x, v.y);
              }
@@ -468,6 +465,7 @@ Item {
              "  return outColor;
              }" +
 
+             shaderLibrary.rasterizationShader +
 
              "void main() {" +
                  "vec2 cc = vec2(0.5) - qt_TexCoord0;" +
@@ -490,8 +488,6 @@ Item {
                      txt_color.b = leftColor.b * 0.30 + rightColor.b * 0.10 + txt_color.b * 0.60;
                  " : "") +
 
-                  "txt_color *= getScanlineIntensity(txt_coords);" +
-
                   "txt_color += vec3(0.0001);" +
                   "float greyscale_color = rgb2grey(txt_color);" +
 

app/qml/TerminalContainer.qml

@@ -26,13 +26,19 @@ ShaderTerminal {
     property alias title: terminal.title
     property alias terminalSize: terminal.terminalSize
 
+    property real devicePixelRatio: terminalWindow.screen.devicePixelRatio
+
     id: mainShader
     opacity: appSettings.windowOpacity * 0.3 + 0.7
 
     source: terminal.mainSource
     burnInEffect: terminal.burnInEffect
     slowBurnInEffect: terminal.slowBurnInEffect
-    virtual_resolution: terminal.virtualResolution
+    virtualResolution: terminal.virtualResolution
+    screenResolution: Qt.size(
+        terminalWindow.width * devicePixelRatio * appSettings.windowScaling,
+        terminalWindow.height * devicePixelRatio * appSettings.windowScaling
+    )
 
     TimeManager {
         id: timeManager

app/qml/resources.qrc

@@ -45,5 +45,6 @@
         <file>menus/WindowMenu.qml</file>
         <file>menus/FullContextMenu.qml</file>
         <file>menus/ShortContextMenu.qml</file>
+        <file>ShaderLibrary.qml</file>
     </qresource>
 </RCC>

app/qml/utils.js

@@ -31,13 +31,18 @@ function lint(a, b, t) {
     return (1 - t) * a + (t) * b;
 }
 
-function mix(c1, c2, alpha){
+function mix(c1, c2, alpha) {
     return Qt.rgba(c1.r * alpha + c2.r * (1-alpha),
                    c1.g * alpha + c2.g * (1-alpha),
                    c1.b * alpha + c2.b * (1-alpha),
                    c1.a * alpha + c2.a * (1-alpha))
 }
 
+function smoothstep(min, max, value) {
+    let x = Math.max(0, Math.min(1, (value - min) / (max - min)));
+    return x * x * (3 - 2 * x);
+}
+
 function strToColor(s){
     var r = parseInt(s.substring(1,3), 16) / 256;
     var g = parseInt(s.substring(3,5), 16) / 256;