implement brush outline

src/app_shaders.cpp

@@ -161,7 +161,15 @@ void App::initShaders()
         "out mediump vec4 frag;\n"
         "void main() {\n"
         "   mediump float stroke = 1.0 - texture(tex, uv).r;\n"
-        "   frag = vec4(col.rgb, stroke * alpha);\n"
+        "   int zero_count = 0;\n"
+        "   for (int x = -1; x <= 1; x++){\n"
+        "       for (int y = -1; y <= 1; y++){\n"
+        "           if (textureOffset(tex, uv, ivec2(x, y)).r == 1.0) \n"
+        "               zero_count++;\n"
+        "       }\n"
+        "   }\n"
+        "   float edge = (zero_count > 1 && zero_count < 9) ? 0.75 : 0.0;\n"
+        "   frag = vec4(col.rgb, edge);\n"
         "}\n";
     // TEXTURE COMP ERASE
     static const char* shader_comp_erase_f =

src/canvas.cpp

@@ -1090,8 +1090,9 @@ bool Canvas::create(int width, int height)
     }
     m_sampler.create(GL_NEAREST);
     m_sampler.create(GL_LINEAR);
-    m_sampler_brush.create();
+    m_sampler_brush.create(GL_LINEAR, GL_CLAMP_TO_BORDER);
     m_sampler_brush.set_filter(GL_LINEAR_MIPMAP_LINEAR, GL_LINEAR);
+    m_sampler_brush.set_border({ 1, 1, 1, 1 });
     m_sampler_bg.create(GL_NEAREST);
     m_sampler_mask.create(GL_LINEAR);
     m_sampler_stencil.create(GL_LINEAR, GL_REPEAT);

src/texture.cpp

@@ -134,6 +134,12 @@ void Sampler::set_filter(GLint filter_min, GLint filter_mag)
     glSamplerParameteri(id, GL_TEXTURE_MAG_FILTER, filter_mag);
 #endif // USE_SAMPLER
 }
+void Sampler::set_border(glm::vec4 rgba)
+{
+#if USE_SAMPLER
+    glSamplerParameterfv(id, GL_TEXTURE_BORDER_COLOR, glm::value_ptr(rgba));
+#endif // USE_SAMPLER
+}
 void Sampler::bind(int unit) const
 {
     current_unit = unit;

src/texture.h

@@ -32,6 +32,7 @@ public:
     bool create(GLint filter = GL_LINEAR, GLint wrap = GL_CLAMP_TO_EDGE);
     void set(GLint filter = GL_LINEAR, GLint wrap = GL_CLAMP_TO_EDGE);
     void set_filter(GLint filter_min, GLint filter_mag);
+    void set_border(glm::vec4 rgba);
     void bind(int unit) const;
     void unbind();
     bool ready() const { return id != 0; }