From 47a43fecb108065487348015ea9b1a3f0a4d4639 Mon Sep 17 00:00:00 2001
From: Gary Talent <gary@drinkingtea.net>
Date: Sat, 20 Mar 2021 15:31:13 -0500
Subject: [PATCH] [nostalgia/core/userland] Cleanup shader cleanup with
 unique_ptr-like GLobject type

---
 src/nostalgia/core/userland/gfx_opengl.cpp |  6 +--
 src/nostalgia/core/userland/glutils.cpp    | 29 +++++-------
 src/nostalgia/core/userland/glutils.hpp    | 51 +++++++++++++++++++++-
 3 files changed, 64 insertions(+), 22 deletions(-)

diff --git a/src/nostalgia/core/userland/gfx_opengl.cpp b/src/nostalgia/core/userland/gfx_opengl.cpp
index 1b3588e6..6cc0a123 100644
--- a/src/nostalgia/core/userland/gfx_opengl.cpp
+++ b/src/nostalgia/core/userland/gfx_opengl.cpp
@@ -38,7 +38,7 @@ struct Background: public Bufferset {
 };
 
 struct GlImplData {
-	GLuint bgShader = 0;
+	Program bgShader;
 	int64_t prevFpsCheckTime = 0;
 	uint64_t draws = 0;
 	std::array<Background, 4> backgrounds;
@@ -191,7 +191,7 @@ static void drawBackgrounds(GlImplData *id) {
 ox::Error init(Context *ctx) {
 	const auto id = new GlImplData;
 	ctx->setRendererData(id);
-	oxReturnError(buildShaderProgram(bgvshad, bgfshad).get(&id->bgShader));
+	oxReturnError(buildShaderProgram(bgvshad, bgfshad).moveTo(&id->bgShader));
 	for (auto &bg : id->backgrounds) {
 		initBackgroundBufferset(ctx, id->bgShader, &bg);
 	}
@@ -200,8 +200,6 @@ ox::Error init(Context *ctx) {
 
 ox::Error shutdown(Context *ctx) {
 	const auto id = ctx->rendererData<GlImplData>();
-	glDeleteProgram(id->bgShader);
-	id->bgShader = 0;
 	for (auto &bg : id->backgrounds) {
 		destroy(bg);
 	}
diff --git a/src/nostalgia/core/userland/glutils.cpp b/src/nostalgia/core/userland/glutils.cpp
index 71635be0..134c5b91 100644
--- a/src/nostalgia/core/userland/glutils.cpp
+++ b/src/nostalgia/core/userland/glutils.cpp
@@ -15,8 +15,11 @@
 
 namespace nostalgia::core::renderer {
 
+template struct GLobject<glDeleteProgram>;
+template struct GLobject<glDeleteShader>;
+
 [[nodiscard]]
-static ox::Result<GLuint> buildShader(GLuint shaderType, const GLchar *src, const char *shaderName) {
+static ox::Result<Shader> buildShader(GLuint shaderType, const GLchar *src, const char *shaderName) {
 	const auto shader = glCreateShader(shaderType);
 	glShaderSource(shader, 1, &src, nullptr);
 	glCompileShader(shader);
@@ -29,26 +32,18 @@ static ox::Result<GLuint> buildShader(GLuint shaderType, const GLchar *src, cons
 		glDeleteShader(shader);
 		return OxError(1, "shader compile error");
 	}
-	return shader;
+	return Shader(shader);
 }
 
 [[nodiscard]]
-ox::Result<GLuint> buildShaderProgram(const GLchar *vert, const GLchar *frag) {
-	ox::Result<GLuint> out;
+ox::Result<Program> buildShaderProgram(const GLchar *vert, const GLchar *frag) {
 	oxRequire(vs, buildShader(GL_VERTEX_SHADER, vert, "vshad"));
-	auto [fs, fserr] = buildShader(GL_FRAGMENT_SHADER, frag, "fshad");
-	if (!fserr) {
-		auto prgm = glCreateProgram();
-		glAttachShader(prgm, vs);
-		glAttachShader(prgm, fs);
-		glLinkProgram(prgm);
-		out = prgm;
-	} else {
-		out = fserr;
-	}
-	glDeleteShader(fs);
-	glDeleteShader(vs);
-	return out;
+	oxRequire(fs, buildShader(GL_FRAGMENT_SHADER, frag, "fshad"));
+	Program prgm(glCreateProgram());
+	glAttachShader(prgm, vs);
+	glAttachShader(prgm, fs);
+	glLinkProgram(prgm);
+	return ox::move(prgm);
 }
 
 void destroy(const Bufferset &bufferset) {
diff --git a/src/nostalgia/core/userland/glutils.hpp b/src/nostalgia/core/userland/glutils.hpp
index 49eaefd7..f5320eb3 100644
--- a/src/nostalgia/core/userland/glutils.hpp
+++ b/src/nostalgia/core/userland/glutils.hpp
@@ -15,9 +15,58 @@
 #endif
 
 #include <ox/std/error.hpp>
+#include <ox/std/trace.hpp>
 
 namespace nostalgia::core::renderer {
 
+template<auto del>
+struct GLobject {
+
+	GLuint id = 0;
+
+	constexpr GLobject() = default;
+
+	explicit constexpr GLobject(GLuint id) {
+		this->id = id;
+	}
+
+	constexpr GLobject(GLobject &&o) {
+		id = o.id;
+		o.id = 0;
+	}
+
+	~GLobject() {
+		oxDebugf("Deleting {}", id);
+		del(id);
+	}
+
+	GLobject &operator=(GLobject &&o) {
+		id = o.id;
+		o.id = 0;
+		return *this;
+	}
+
+	constexpr GLuint release() noexcept {
+		auto out = id;
+		id = 0;
+		return out;
+	}
+
+	constexpr operator GLuint&() noexcept {
+		return id;
+	}
+
+	constexpr operator const GLuint&() const noexcept {
+		return id;
+	}
+
+};
+
+extern template struct GLobject<glDeleteProgram>;
+extern template struct GLobject<glDeleteShader>;
+using Shader = GLobject<glDeleteShader>;
+using Program = GLobject<glDeleteProgram>;
+
 struct Texture {
 
 	GLuint texId = 0;
@@ -43,7 +92,7 @@ struct Bufferset {
 };
 
 [[nodiscard]]
-ox::Result<GLuint> buildShaderProgram(const GLchar *vert, const GLchar *frag);
+ox::Result<Program> buildShaderProgram(const GLchar *vert, const GLchar *frag);
 
 void destroy(const Bufferset &bufferset);