Shaders: add a "screenshot" for LineGL.

OMG PRETTY!!!

doc/generated/shaders.cpp

@@ -55,12 +55,14 @@
 #include <Magnum/Math/Matrix3.h>
 #include <Magnum/Math/Matrix4.h>
 #include <Magnum/MeshTools/Compile.h>
+#include <Magnum/MeshTools/CompileLines.h>
 #include <Magnum/MeshTools/Interleave.h>
 #include <Magnum/Primitives/Square.h>
 #include <Magnum/Primitives/Circle.h>
 #include <Magnum/Primitives/Icosphere.h>
 #include <Magnum/Primitives/UVSphere.h>
 #include <Magnum/Shaders/FlatGL.h>
+#include <Magnum/Shaders/LineGL.h>
 #include <Magnum/Shaders/MeshVisualizerGL.h>
 #include <Magnum/Shaders/PhongGL.h>
 #include <Magnum/Shaders/VertexColorGL.h>
@@ -80,6 +82,7 @@ struct ShaderVisualizer: Platform::WindowlessApplication {
     int exec() override;
 
     Containers::StringView phong();
+    Containers::StringView line();
     Containers::StringView meshVisualizer2D();
     Containers::StringView meshVisualizer2DPrimitiveId();
     Containers::StringView meshVisualizer3D();
@@ -132,6 +135,7 @@ int ShaderVisualizer::exec() {
     GL::Renderer::setClearColor(0x000000_srgbaf);
 
     for(auto fun: {&ShaderVisualizer::phong,
+                   &ShaderVisualizer::line,
                    &ShaderVisualizer::meshVisualizer2D,
                    &ShaderVisualizer::meshVisualizer2DPrimitiveId,
                    &ShaderVisualizer::meshVisualizer3D,
@@ -175,6 +179,43 @@ Containers::StringView ShaderVisualizer::phong() {
     return "phong.png";
 }
 
+Containers::StringView ShaderVisualizer::line() {
+    struct Vertex {
+        Vector2 position;
+        Color3ub color;
+    };
+    Containers::Array<Vertex> vertices{NoInit, 1024};
+    const auto map = DebugTools::ColorMap::turbo();
+
+    for(std::size_t i = 0; i != vertices.size(); ++i) {
+        const Rad t{Constants::tau()*Float(i)/Float(vertices.size())};
+        vertices[i].position = {
+            /* Original from https://www.quantamagazine.org/how-to-create-art-with-mathematics-20151008/
+                Math::cos(t) + Math::cos(6*t)/2 + Math::sin(14*t)/3,
+                Math::sin(t) + Math::sin(6*t)/2 + Math::cos(14*t)/3 */
+            Math::cos(t) + Math::cos(6*t)/3 + Math::sin(14*t)/3,
+            Math::sin(t) + Math::sin(6*t)/3 + Math::cos(14*t)/3
+        };
+        vertices[i].color = map[i/4];
+    }
+
+    Trade::MeshData mesh{MeshPrimitive::LineLoop, {}, vertices, {
+        Trade::MeshAttributeData{Trade::MeshAttribute::Position, stridedArrayView(vertices).slice(&Vertex::position)},
+        Trade::MeshAttributeData{Trade::MeshAttribute::Color, stridedArrayView(vertices).slice(&Vertex::color)},
+    }};
+
+    Shaders::LineGL2D shader{Shaders::LineGL2D::Configuration{}
+        .setFlags(Shaders::LineGL2D::Flag::VertexColor)};
+    shader
+        .setTransformationProjectionMatrix(Matrix3::scaling(Vector2{0.5f}))
+        .setViewportSize(Vector2{ImageSize})
+        .setWidth(5.0f)
+        .setSmoothness(1.0f)
+        .draw(MeshTools::compileLines(mesh));
+
+    return "line.png";
+}
+
 Containers::StringView ShaderVisualizer::meshVisualizer2D() {
     const Matrix3 projection =
         Matrix3::projection(Vector2{3.0f})*

doc/namespaces.dox

@@ -685,19 +685,24 @@ See @ref building, @ref cmake and @ref shaders for more information.
 
 @parblock
 
-@m_div{m-col-m-4 m-col-t-6 m-text-center m-nopadt m-nopadx}
+@m_div{m-col-m-3 m-col-t-6 m-text-center m-nopadt m-nopadx}
 @image html shaders-flat.png width=256px
 @ref FlatGL @m_class{m-label m-success} **2D** @m_class{m-label m-primary} **3D**
 @m_enddiv
 
-@m_div{m-col-m-4 m-col-t-6 m-text-center m-nopadt m-nopadx}
+@m_div{m-col-m-3 m-col-t-6 m-text-center m-nopadt m-nopadx}
 @image html shaders-phong.png width=256px
 @ref PhongGL @m_class{m-label m-primary} **3D**
 @m_enddiv
 
 @m_div{m-clearfix-t} @m_enddiv
 
-@m_div{m-col-m-4 m-push-t-3 m-push-m-0 m-col-t-6 m-text-center m-nopadt m-nopadx}
+@m_div{m-col-m-3 m-col-t-6 m-text-center m-nopadt m-nopadx}
+@image html shaders-line.png width=256px
+@ref LineGL @m_class{m-label m-success} **2D** @m_class{m-label m-primary} **3D**
+@m_enddiv
+
+@m_div{m-col-m-3 m-col-t-6 m-text-center m-nopadt m-nopadx}
 @image html shaders-vertexcolor.png width=256px
 @ref VertexColorGL @m_class{m-label m-success} **2D** @m_class{m-label m-primary} **3D**
 @m_enddiv

src/Magnum/Shaders/LineGL.h

@@ -68,6 +68,8 @@ Renders lines expanded to quads in screen space. Compared to builtin GPU line
 rendering, the lines can be of arbitrary width, with configurable join and cap
 styles, and antialiased independently of MSAA being used or not.
 
+@image html shaders-line.png width=256px
+
 @requires_gl30 Extension @gl_extension{EXT,gpu_shader4}
 @requires_gles30 Requires integer support in shaders which is not available in
     OpenGL ES 2.0.