Migrate to NanoGUI / Eigen for GUI and linear algebra.

Also introduce a GUI play/pause button.

vis/include/cgl/shader.hpp

@@ -0,0 +1,80 @@
+#pragma once
+
+#include <string>
+#include <utility>
+
+#include <nanogui/opengl.h>
+
+#include <cgl/error.hpp>
+
+#include <util.hpp>
+
+namespace cgl {
+    template<GLenum mode>
+    class Shader {
+    protected:
+        GLuint id{};
+
+    public:
+        Shader() {
+            id = glCreateShader(mode);
+        }
+
+        Shader(const std::string &src) : Shader() {
+            set_source(src);
+
+            if (!compile())
+                throw ShaderError(get_info_log());
+        }
+
+        static Shader<mode> file(const std::string &name) {
+            return Shader<mode>(utilReadFile(name));
+        }
+
+        Shader(Shader &) = delete;
+
+        Shader(Shader &&o) noexcept {
+            id = std::exchange(o.id, 0);
+        };
+
+        ~Shader() {
+            glDeleteShader(id);
+        }
+
+        operator GLuint() const {
+            return id;
+        }
+
+        [[nodiscard]] int get(GLenum pname) const {
+            GLint res;
+            glGetShaderiv(id, pname, &res);
+            return (int) res;
+        }
+
+        [[nodiscard]] std::string get_info_log() const {
+            auto len = (size_t) get(GL_INFO_LOG_LENGTH);
+            char buffer[len];
+            glGetShaderInfoLog(id, len, nullptr, buffer);
+            return std::string(buffer);
+        }
+
+        void set_source(const std::string &src) {
+            const char *c_src = src.c_str();
+            glShaderSource(id, 1, &c_src, nullptr);
+        }
+
+        bool compile() {
+            glCompileShader(id);
+            return (bool) get(GL_COMPILE_STATUS);
+        }
+    };
+
+    namespace sh {
+        using vert = Shader<GL_VERTEX_SHADER>;
+        using tcs = Shader<GL_TESS_CONTROL_SHADER>;
+        using tes = Shader<GL_TESS_EVALUATION_SHADER>;
+        using geom = Shader<GL_GEOMETRY_SHADER>;
+        using frag = Shader<GL_FRAGMENT_SHADER>;
+        using comp = Shader<GL_COMPUTE_SHADER>;
+    }
+}