Migrate to NanoGUI / Eigen for GUI and linear algebra.

Also introduce a GUI play/pause button.

vis/include/cgl/vertexarray.hpp

@@ -0,0 +1,75 @@
+#pragma once
+
+#include <functional>
+#include <string>
+#include <utility>
+
+#include <nanogui/opengl.h>
+
+#include <cgl/error.hpp>
+#include <cgl/buffer.hpp>
+
+namespace cgl {
+    class VertexArray {
+        GLuint id{};
+
+    public:
+        VertexArray() {
+            glCreateVertexArrays(1, &id);
+        }
+
+        VertexArray(VertexArray &) = delete;
+
+        VertexArray(VertexArray &&o) noexcept {
+            id = std::exchange(o.id, 0);
+        }
+
+        ~VertexArray() {
+            glDeleteVertexArrays(1, &id);
+            id = 0;
+        }
+
+        operator GLuint() const {
+            return id;
+        }
+
+        void bound(const std::function<void()> &action) const {
+            glBindVertexArray(id);
+            action();
+            glBindVertexArray(0);
+        }
+
+        template<class T>
+        void pointer(
+            GLuint index,
+            const Buffer<T> &buf,
+            unsigned size,
+            GLenum type,
+            bool normalized = false,
+            unsigned stride = 0
+        ) const {
+            bound([&]() {
+                glEnableVertexAttribArray(index);
+                buf.bound(GL_ARRAY_BUFFER, [&]() {
+                    glVertexAttribPointer(index, size, type, normalized, stride, nullptr);
+                });
+            });
+        }
+
+        template<class T>
+        void ipointer(
+            GLuint index,
+            const Buffer<T> &buf,
+            unsigned size,
+            GLenum type,
+            unsigned stride = 0
+        ) const {
+            bound([&]() {
+                glEnableVertexAttribArray(index);
+                buf.bound(GL_ARRAY_BUFFER, [&]() {
+                    glVertexAttribIPointer(index, size, type, stride, nullptr);
+                });
+            });
+        }
+    };
+}