Triangles fade from bottom and behave better on antialiased mask edges

default.vert

@@ -0,0 +1,12 @@
+#version 440
+layout(location = 0) in vec4 qt_Vertex;
+layout(location = 1) in vec2 qt_MultiTexCoord0;
+layout(location = 0) out vec2 coord;
+layout(std140, binding = 0) uniform buf {
+    mat4 qt_Matrix;
+    float qt_Opacity;
+};
+void main() {
+    coord = qt_MultiTexCoord0;
+    gl_Position = qt_Matrix * qt_Vertex;
+}