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feat: render spinning 3D cube with glm

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- Add glm dependency for matrix transformations
- Replace triangle with 6-face colored cube
- Add MVP shader uniforms (model, view, projection)
- Enable depth testing for proper 3D rendering
- Spin cube around (1, 0.5, 0.3) axis

style: fix trailing return type for move assignment operators

- buffer/texture/shader/vao: use auto fn() -> T& style
- Document trailing return type convention in AGENTS.md
This commit is contained in:
portersky
2026-05-05 22:19:33 +02:00
parent 9114eaabc6
commit 30ddaf7d39
7 changed files with 91 additions and 18 deletions
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AGENTS.md
+2 -1
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@@ -38,11 +38,12 @@ to the custom scripts instead of system-installed packages.
## Coding Conventions
- **Language:** C++23
- **Trailing return type** for function signatures
- **Trailing return type** for function signatures (e.g. `auto fn() -> void`)
- **4-space indentation**
- **No semicolons after closing braces** for namespaces/classes
- `auto` for obvious types (e.g. `auto main(...) -> int`)
- **East const** (e.g. `char const*` not `const char*`)
- **Trailing return type** for all function definitions, including operators (e.g. `auto operator=(T&&) noexcept -> T&`)
- `<>` includes only for system headers (std, OS, etc.)
- `""` includes for third-party dependencies (e.g. `fmt`, `nlohmann/json`)
- **Naming:** `snake_case` for variables, functions, and classes
CMakeLists.txt
+2 -1
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@@ -16,6 +16,7 @@ find_package(fmt REQUIRED)
find_package(glfw3 REQUIRED)
find_package(glad REQUIRED)
find_package(asio REQUIRED)
find_package(glm REQUIRED)
# Target setup
add_executable(cuber "cuber.cpp"
@@ -30,4 +31,4 @@ target_include_directories(cuber PRIVATE ".")
target_compile_features(cuber PRIVATE cxx_std_23)
target_compile_options(cuber PRIVATE ${BASE_OPTIONS})
target_compile_definitions(cuber PRIVATE ${BASE_DEFINITIONS})
target_link_libraries(cuber PRIVATE fmt::fmt glfw::glfw glad::glad asio::asio ${BASE_LIBRARIES})
target_link_libraries(cuber PRIVATE fmt::fmt glfw::glfw glad::glad asio::asio glm::glm ${BASE_LIBRARIES})
cbt/opengl/buffer.cpp
+1 -1
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@@ -25,7 +25,7 @@ buffer::buffer(buffer&& other) noexcept
other.m_id = 0;
}
buffer& buffer::operator=(buffer&& other) noexcept {
auto buffer::operator=(buffer&& other) noexcept -> buffer& {
if (this != &other) {
if (m_id) {
glDeleteBuffers(1, &m_id);
cbt/opengl/shader.cpp
+1 -1
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@@ -20,7 +20,7 @@ shader::shader(shader&& other) noexcept
other.m_id = 0;
}
shader& shader::operator=(shader&& other) noexcept {
auto shader::operator=(shader&& other) noexcept -> shader& {
if (this != &other) {
if (m_id) {
glDeleteProgram(m_id);
cbt/opengl/texture.cpp
+1 -1
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@@ -25,7 +25,7 @@ texture::texture(texture&& other) noexcept
other.m_id = 0;
}
texture& texture::operator=(texture&& other) noexcept {
auto texture::operator=(texture&& other) noexcept -> texture& {
if (this != &other) {
if (m_id) {
glDeleteTextures(1, &m_id);
cbt/opengl/vao.cpp
+1 -1
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@@ -17,7 +17,7 @@ vao::vao(vao&& other) noexcept
other.m_id = 0;
}
vao& vao::operator=(vao&& other) noexcept {
auto vao::operator=(vao&& other) noexcept -> vao& {
if (this != &other) {
if (m_id) {
glDeleteVertexArrays(1, &m_id);
cuber.cpp
+83 -12
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@@ -6,10 +6,16 @@
#include "cbt/opengl/buffer.hpp"
#include "cbt/opengl/vao.hpp"
#include "asio.hpp"
#include <chrono>
#include <asio.hpp>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "glad/glad.h"
auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
auto main(int, char const*[]) -> int {
auto ctx = cbt::opengl::context("cuber", 1280, 720);
if (!ctx.valid()) {
@@ -23,9 +29,12 @@ auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
#version 410 core
layout(location = 0) in vec3 a_pos;
layout(location = 1) in vec3 a_color;
uniform mat4 u_model;
uniform mat4 u_view;
uniform mat4 u_proj;
out vec3 v_color;
void main() {
gl_Position = vec4(a_pos, 1.0);
gl_Position = u_proj * u_view * u_model * vec4(a_pos, 1.0);
v_color = a_color;
}
)glsl";
@@ -43,12 +52,56 @@ auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
return 1;
}
// vertex data: triangle with per-vertex colors
// red, green, blue corners
std::array<float, 18> vertices = {
-0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f,
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.5f, 0.0f, 0.0f, 0.0f, 1.0f,
// cube vertices: 6 faces, 2 triangles per face, 3 verts each = 36 vertices
// each vertex: x, y, z, r, g, b
std::array<float, 36 * 6> vertices = {
// front face (cyan)
0.5f, -0.5f, 0.5f, 0.0f, 1.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 0.0f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 0.0f, 1.0f, 1.0f,
-0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 1.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 1.0f,
// back face (magenta)
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 1.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 1.0f,
0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 1.0f,
// top face (yellow)
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.0f,
// bottom face (white)
0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f,
0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f,
-0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f,
0.5f, -0.5f, 0.5f, 1.0f, 1.0f, 1.0f,
// right face (lime)
0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, -0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f,
0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
// left face (orange)
-0.5f, -0.5f, -0.5f, 1.0f, 0.5f, 0.0f,
-0.5f, -0.5f, 0.5f, 1.0f, 0.5f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.5f, 0.0f,
-0.5f, -0.5f, -0.5f, 1.0f, 0.5f, 0.0f,
-0.5f, 0.5f, 0.5f, 1.0f, 0.5f, 0.0f,
-0.5f, 0.5f, -0.5f, 1.0f, 0.5f, 0.0f,
};
auto vbo = cbt::opengl::buffer(cbt::opengl::buffer_type::vertex);
@@ -66,6 +119,9 @@ auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
vbo.unbind();
vao.unbind();
// enable depth testing
glEnable(GL_DEPTH_TEST);
// signal handling
asio::io_context io;
asio::signal_set signals(io, SIGINT, SIGTERM);
@@ -81,6 +137,8 @@ auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
};
// render loop
auto start = std::chrono::steady_clock::now();
while (!ctx.should_close()) {
process_signals();
@@ -88,12 +146,25 @@ auto main([[maybe_unused]]int argc, [[maybe_unused]]char const* argv[]) -> int {
break;
}
glClearColor(0.6f, 0.8f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
auto now = std::chrono::steady_clock::now();
auto elapsed = std::chrono::duration<float>(now - start).count();
glClearColor(0.15f, 0.15f, 0.2f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// compute MVP matrices
auto aspect = 1280.0f / 720.0f;
auto proj = glm::perspective(glm::radians(45.0f), aspect, 0.1f, 100.0f);
auto view = glm::translate(glm::mat4{1.0f}, glm::vec3{0.0f, 0.0f, -3.0f});
auto model = glm::rotate(glm::mat4{1.0f}, elapsed, glm::vec3{1.0f, 0.5f, 0.3f});
prog.use();
glUniformMatrix4fv(glGetUniformLocation(prog.id(), "u_proj"), 1, GL_FALSE, glm::value_ptr(proj));
glUniformMatrix4fv(glGetUniformLocation(prog.id(), "u_view"), 1, GL_FALSE, glm::value_ptr(view));
glUniformMatrix4fv(glGetUniformLocation(prog.id(), "u_model"), 1, GL_FALSE, glm::value_ptr(model));
vao.bind();
glDrawArrays(GL_TRIANGLES, 0, 3);
glDrawArrays(GL_TRIANGLES, 0, 36);
vao.unbind();
prog.unuse();