add stencil alpha control to ui

data/layout.xml

@@ -152,6 +152,7 @@
             <node height="20" justify="center"><text text="Spacing" font-face="arial" font-size="11"/></node>
             <node height="20" justify="center"><text text="Angle" font-face="arial" font-size="11"/></node>
             <node height="20" justify="center"><text text="Mixer" font-face="arial" font-size="11"/></node>
+            <node height="20" justify="center"><text text="Stencil" font-face="arial" font-size="11"/></node>
           </node>
           <border dir="col" align="center" grow="1" width="1">
             <node height="20" pad="1" width="100%" dir="row">
@@ -175,6 +176,7 @@
               </node>
             </node>
             <node height="20" pad="1" width="100%"><slider-h id="tip-mix"/></node>
+            <node height="20" pad="1" width="100%"><slider-h id="tip-stencil"/></node>
           </border>
         </node>
         

engine/app_shaders.cpp

@@ -248,6 +248,7 @@ void App::initShaders()
         "uniform mediump vec2 resolution;\n"
         "uniform mediump float alpha;\n"
         "uniform mediump vec2 stencil_offset;\n"
+        "uniform mediump float stencil_alpha;\n"
         "in mediump vec2 uv;\n"
         "in mediump float q;\n"
 #ifdef __IOS__
@@ -257,7 +258,7 @@ void App::initShaders()
 #endif
         "void main(){\n"
         "   mediump vec2 uv2 = gl_FragCoord.st / resolution;\n"
-        "   mediump float stencil = 1-(texture(tex_stencil, (uv2+stencil_offset) * 5.0).r * 0.9);\n"
+        "   mediump float stencil = 1-(texture(tex_stencil, (uv2+stencil_offset) * 5.0).r * 0.9) * stencil_alpha;\n"
         "   mediump float brush_alpha = ( 1.0 - texture(tex, uv/q).r ) * alpha;\n"
         "   mediump vec4 fg = vec4(col.rgb, brush_alpha);\n"
 #ifdef __IOS__

engine/brush.h

@@ -16,6 +16,7 @@ public:
     float m_tip_flow = 0;
     float m_tip_opacity = 0;
     float m_tip_angle = 0;
+    float m_tip_stencil = 0;
     bool  m_tip_angle_follow = false;
     bool  m_tip_flow_pressure = false;
     bool  m_tip_size_pressure = false;

engine/canvas.cpp

@@ -243,6 +243,7 @@ void ui::Canvas::stroke_draw()
             ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
             ShaderManager::u_vec2(kShaderUniform::Resolution, { m_width, m_height });
             ShaderManager::u_vec2(kShaderUniform::StencilOffset, glm::vec2((rand()%1000)*0.001f, (rand()%1000)*0.001f));
+            ShaderManager::u_float(kShaderUniform::StencilAlpha, m_brush.m_tip_stencil);
             for (const auto& s : samples)
             {
                 glm::vec2 dx(s.size * 0.5f, 0), dy(0, s.size * 0.5f);

engine/node_panel_stroke.cpp

@@ -26,6 +26,7 @@ void NodePanelStroke::set_params(const ui::Brush &b)
     m_tip_flow->m_value.x = glm::pow(b.m_tip_flow, 1.f/2.f);
     m_tip_opacity->m_value.x = b.m_tip_opacity;
     m_tip_angle->m_value.x = b.m_tip_angle;
+    m_tip_stencil->m_value.x = b.m_tip_stencil;
     m_jitter_scale->m_value.x = b.m_jitter_scale;
     m_jitter_angle->m_value.x = b.m_jitter_angle;
     m_jitter_spread->m_value.x = b.m_jitter_spread;
@@ -46,6 +47,7 @@ void NodePanelStroke::init_controls()
     init_slider(m_tip_flow, "tip-flow", &ui::Brush::m_tip_flow);
     init_slider(m_tip_opacity, "tip-opacity", &ui::Brush::m_tip_opacity);
     init_slider(m_tip_angle, "tip-angle", &ui::Brush::m_tip_angle);
+    init_slider(m_tip_stencil, "tip-stencil", &ui::Brush::m_tip_stencil);
     init_slider(m_jitter_scale, "jitter-scale", &ui::Brush::m_jitter_scale);
     init_slider(m_jitter_angle, "jitter-angle", &ui::Brush::m_jitter_angle);
     init_slider(m_jitter_spread, "jitter-spread", &ui::Brush::m_jitter_spread);

engine/node_panel_stroke.h

@@ -14,6 +14,7 @@ public:
     NodeSliderH* m_tip_flow;
     NodeSliderH* m_tip_opacity;
     NodeSliderH* m_tip_angle;
+    NodeSliderH* m_tip_stencil;
     NodeSliderH* m_jitter_scale;
     NodeSliderH* m_jitter_angle;
     NodeSliderH* m_jitter_spread;

engine/shader.h

@@ -13,6 +13,7 @@ enum class kShaderUniform : uint16_t
     TexStroke = const_hash("tex_stroke"),
     TexStencil= const_hash("tex_stencil"),
     StencilOffset = const_hash("stencil_offset"),
+    StencilAlpha = const_hash("stencil_alpha"),
     Lock = const_hash("lock"),
     Col = const_hash("col"),
     Tof = const_hash("tof"),