dual-brush blend modes

data/layout.xml

@@ -360,7 +360,7 @@
               </node>
             </node>
             <node height="30" width="100%" pad="1" dir="row" margin="0 0 5 0">
-              <combobox id="db-blend" width="100%" height="28" combo-list="Normal,-,Multiply,Screen,-,Color Dodge,Overlay" default="0"/>
+              <combobox id="dual-blend-mode" width="100%" height="28" combo-list="Normal,-,Multiply,Screen,-,Color Dodge,Overlay" default="0"/>
             </node>
             <node align="center" dir="row">
               <checkbox id="dual-randflip" height="20" width="20"/>

src/app_shaders.cpp

@@ -38,6 +38,16 @@
     "   else return vec4(1, 0, 0, 1);\n"\
     "}\n"
 
+#define SHADER_FUNCTION_BLEND_STROKE \
+    "mediump float blend_stroke(mediump float base, mediump float stroke, int mode) {\n"\
+    "   if      (mode == 0) return (base + stroke) * 0.5;\n"\
+    "   else if (mode == 1) return base * stroke;\n"\
+    "   else if (mode == 2) return 1.0-(1.0-base)*(1.0-stroke);\n"\
+    "   else if (mode == 3) return base/(1.0-stroke);\n"\
+    "   else if (mode == 4) return mix(2.0*base*stroke, 1.0-2.0*(1.0-base)*(1.0-stroke), floor(base*2.0));\n"\
+    "   else return 1;\n"\
+    "}\n"
+
 #define SHADER_FUNCTION_HSV \
     "mediump vec3 rgb2hsv(mediump vec3 c) {\n"\
     "    mediump vec4 k = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);\n"\
@@ -223,13 +233,16 @@ void App::initShaders()
         "out mediump vec4 frag;\n"
         SHADER_FUNCTION_BLUR
         SHADER_FUNCTION_BLEND
+        SHADER_FUNCTION_BLEND_STROKE
         "void main() {\n"
         "   mediump vec2 uv2 = fragUV2 ? (gl_FragCoord.st / resolution) : uv;\n"
         "   mediump vec4 base = texture(tex, uv2);\n"
         "   mediump vec4 stroke = texture(tex_stroke, uv);\n"
+        "   if (use_dual){\n"
         "       mediump vec4 dual = texture(tex_dual, uv);\n"
-        "   if (use_dual)\n"
+        //"       stroke.a = stroke.a * dual.a;\n"
-        "       stroke.a = stroke.a * dual.a;\n"
+        "       stroke.a = blend_stroke(stroke.a, dual.a, dual_blend_mode);\n"
+        "   }\n"
         "   stroke.a = mask ? stroke.a * stroke_alpha * blur(tex_mask, uv2).r : stroke.a * stroke_alpha;\n"
         "   if (!lock && base.a == 0.0) { frag = stroke * vec4(1.0, 1.0, 1.0, alpha); return; }\n"
         "   mediump vec4 blended = blend(base, stroke, blend_mode);\n"

src/canvas.cpp

@@ -562,8 +562,12 @@ void Canvas::stroke_draw()
                 if (P.size() < 3)
                     continue;
                 m_tmp_dual[i].bindFramebuffer();
-                stroke_draw_samples(i, P);
+                auto rect = stroke_draw_samples(i, P);
                 m_tmp_dual[i].unbindFramebuffer();
+
+                // this mode overflows the main brush boundries
+                if (brush->m_dual_blend_mode == 0)
+                    m_dirty_box[i] = glm::clamp(box_union(m_dirty_box[i], rect), glm::vec4(0), glm::vec4(m_width));
             }
         }
         glActiveTexture(GL_TEXTURE2);
@@ -791,8 +795,8 @@ void Canvas::stroke_commit()
             ShaderManager::u_int(kShaderUniform::BlendMode, m_current_stroke->m_brush->m_blend_mode);
             ShaderManager::u_mat4(kShaderUniform::MVP, glm::ortho(-.5f, .5f, -.5f, .5f, -1.f, 1.f));
             ShaderManager::u_int(kShaderUniform::TexDual, 3);
-            ShaderManager::u_int(kShaderUniform::UseDual, true);
+            ShaderManager::u_int(kShaderUniform::UseDual, m_current_stroke->m_brush->m_dual_enabled);
-            ShaderManager::u_int(kShaderUniform::DualBlendMode, 1);
+            ShaderManager::u_int(kShaderUniform::DualBlendMode, m_current_stroke->m_brush->m_dual_blend_mode);
 
             glActiveTexture(GL_TEXTURE0);
             m_tex2[i].bind();

src/node_canvas.cpp

@@ -214,8 +214,8 @@ void NodeCanvas::draw()
                 ShaderManager::u_int(kShaderUniform::BlendMode, m_canvas->m_current_stroke->m_brush->m_blend_mode);
                 ShaderManager::u_mat4(kShaderUniform::MVP, plane_mvp_z);
                 ShaderManager::u_int(kShaderUniform::TexDual, 3);
-                ShaderManager::u_int(kShaderUniform::UseDual, true);
+                ShaderManager::u_int(kShaderUniform::UseDual, m_canvas->m_current_stroke->m_brush->m_dual_enabled);
-                ShaderManager::u_int(kShaderUniform::DualBlendMode, 1);
+                ShaderManager::u_int(kShaderUniform::DualBlendMode, m_canvas->m_current_stroke->m_brush->m_dual_blend_mode);
 
                 glActiveTexture(GL_TEXTURE0);
                 m_canvas->m_layers[layer_index].m_rtt[plane_index].bindTexture();

src/node_panel_stroke.cpp

@@ -146,11 +146,9 @@ void NodePanelStroke::init_controls()
             m_preview->draw_stroke();
             m_preset_preview->draw_stroke();
             m_brush_thumb->set_image(b->m_brush_thumb_path);
+            m_dual_brush_thumb->set_image(b->m_dual_thumb_path);
             m_preset_thumb->set_image(b->m_brush_thumb_path);
             update_controls();
-
-            //m_presets_popup->mouse_release();
-            //m_presets_popup->parent->remove_child(m_presets_popup.get());
         };
     };
 
@@ -299,7 +297,7 @@ void NodePanelStroke::init_controls()
             on_stroke_change(this);
     };
 
-    m_dual_blend_mode = find<NodeComboBox>("blend-mode");
+    m_dual_blend_mode = find<NodeComboBox>("dual-blend-mode");
     m_dual_blend_mode->on_select = [this](Node*, int index) {
         Canvas::I->m_current_brush->m_dual_blend_mode = index;
         m_preview->draw_stroke();

src/shader.h

@@ -28,7 +28,7 @@ enum class kShaderUniform : uint16_t
     Resolution = const_hash("resolution"),
     Highlight = const_hash("highlight"),
     BlendMode = const_hash("blend_mode"),
-    DualBlendMode = const_hash("blend_mode"),
+    DualBlendMode = const_hash("dual_blend_mode"),
     Noise = const_hash("noise"),
     Direction = const_hash("dir"),
     UseFragCoordUV2 = const_hash("fragUV2"),