feat: render per-vertex color triangle

- Add shader class for vertex/fragment program compilation
- Add vao class for vertex array object management
- Render RGB gradient triangle with interpolated vertex colors

cbt/opengl/shader.cpp

@@ -0,0 +1,110 @@
+#include "cbt/opengl/shader.hpp"
+
+#include <iostream>
+#include <string>
+
+#include "fmt/std.h"
+
+namespace cbt::opengl {
+
+shader::shader() {}
+
+shader::~shader() {
+    if (m_id) {
+        glDeleteProgram(m_id);
+    }
+}
+
+shader::shader(shader&& other) noexcept
+    : m_id(other.m_id) {
+    other.m_id = 0;
+}
+
+shader& shader::operator=(shader&& other) noexcept {
+    if (this != &other) {
+        if (m_id) {
+            glDeleteProgram(m_id);
+        }
+        m_id = other.m_id;
+        other.m_id = 0;
+    }
+    return *this;
+}
+
+auto shader::compile_vertex(const char* source) -> bool {
+    auto vert = glCreateShader(GL_VERTEX_SHADER);
+    glShaderSource(vert, 1, &source, nullptr);
+    glCompileShader(vert);
+
+    GLint success;
+    glGetShaderiv(vert, GL_COMPILE_STATUS, &success);
+    if (!success) {
+        GLchar info[512];
+        glGetShaderInfoLog(vert, 512, nullptr, info);
+        fmt::print("Vertex shader compile error:\n{}\n", info);
+        glDeleteShader(vert);
+        return false;
+    }
+
+    if (m_id) {
+        glDeleteProgram(m_id);
+    }
+    m_id = glCreateProgram();
+    glAttachShader(m_id, vert);
+    glDeleteShader(vert);
+    return true;
+}
+
+auto shader::compile_fragment(const char* source) -> bool {
+    auto frag = glCreateShader(GL_FRAGMENT_SHADER);
+    glShaderSource(frag, 1, &source, nullptr);
+    glCompileShader(frag);
+
+    GLint success;
+    glGetShaderiv(frag, GL_COMPILE_STATUS, &success);
+    if (!success) {
+        GLchar info[512];
+        glGetShaderInfoLog(frag, 512, nullptr, info);
+        fmt::print("Fragment shader compile error:\n{}\n", info);
+        glDeleteShader(frag);
+        return false;
+    }
+
+    glAttachShader(m_id, frag);
+    glDeleteShader(frag);
+    return true;
+}
+
+auto shader::link() -> bool {
+    glLinkProgram(m_id);
+
+    GLint success;
+    glGetProgramiv(m_id, GL_LINK_STATUS, &success);
+    if (!success) {
+        GLchar info[512];
+        glGetProgramInfoLog(m_id, 512, nullptr, info);
+        fmt::print("Shader link error:\n{}\n", info);
+        glDeleteProgram(m_id);
+        m_id = 0;
+        return false;
+    }
+    return true;
+}
+
+auto shader::use() const -> void {
+    glUseProgram(m_id);
+}
+
+auto shader::unuse() const -> void {
+    glUseProgram(0);
+}
+
+auto shader::id() const -> GLuint {
+    return m_id;
+}
+
+auto shader::valid() const -> bool {
+    return m_id != 0;
+}
+
+}

cbt/opengl/shader.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <string>
+
+#include "glad/glad.h"
+
+namespace cbt::opengl {
+
+class shader {
+    GLuint m_id = 0;
+
+public:
+    shader();
+    ~shader();
+
+    shader(const shader&) = delete;
+    shader& operator=(const shader&) = delete;
+
+    shader(shader&& other) noexcept;
+    shader& operator=(shader&& other) noexcept;
+
+    auto compile_vertex(const char* source) -> bool;
+    auto compile_fragment(const char* source) -> bool;
+    auto link() -> bool;
+    auto use() const -> void;
+    auto unuse() const -> void;
+    auto id() const -> GLuint;
+    auto valid() const -> bool;
+};
+
+}

cbt/opengl/vao.cpp

@@ -0,0 +1,47 @@
+#include "cbt/opengl/vao.hpp"
+
+namespace cbt::opengl {
+
+vao::vao() {
+    glGenVertexArrays(1, &m_id);
+}
+
+vao::~vao() {
+    if (m_id) {
+        glDeleteVertexArrays(1, &m_id);
+    }
+}
+
+vao::vao(vao&& other) noexcept
+    : m_id(other.m_id) {
+    other.m_id = 0;
+}
+
+vao& vao::operator=(vao&& other) noexcept {
+    if (this != &other) {
+        if (m_id) {
+            glDeleteVertexArrays(1, &m_id);
+        }
+        m_id = other.m_id;
+        other.m_id = 0;
+    }
+    return *this;
+}
+
+auto vao::bind() const -> void {
+    glBindVertexArray(m_id);
+}
+
+auto vao::unbind() const -> void {
+    glBindVertexArray(0);
+}
+
+auto vao::id() const -> GLuint {
+    return m_id;
+}
+
+auto vao::valid() const -> bool {
+    return m_id != 0;
+}
+
+}

cbt/opengl/vao.hpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "glad/glad.h"
+
+namespace cbt::opengl {
+
+class vao {
+    GLuint m_id = 0;
+
+public:
+    vao();
+    ~vao();
+
+    vao(const vao&) = delete;
+    vao& operator=(const vao&) = delete;
+
+    vao(vao&& other) noexcept;
+    vao& operator=(vao&& other) noexcept;
+
+    auto bind() const -> void;
+    auto unbind() const -> void;
+    auto id() const -> GLuint;
+    auto valid() const -> bool;
+};
+
+}