portersky
5ec8cfc735
Add cbt/gfx layer (pipeline + render_target) inspired by Sokol but C++-friendly with RAII and pipeline_desc. Supports building full graphics pipelines (VS/IA/raster/PS/OM), render-to-texture (FBO), and post-processing steps (scene -> RT -> fullscreen quad with sampler + vignette). - Depth/state/viewport/texture cleanup for reliable scene switching. - Updated cube/sphere to demonstrate (sphere uses RT+post). - Vulkan backend easy via PIMPL in impl (same public API). - Fixed depth test, viewport restore, and state leakage on switch. Followed coding conventions (snake_case, trailing returns, east const, include order, no ; after ns/class, etc.).
255 lines
8.5 KiB
C++
255 lines
8.5 KiB
C++
#include <cstddef>
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#include <cmath>
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#include <vector>
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#include <span>
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#include <array>
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#include "glad/glad.h"
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#include "glm/gtc/matrix_transform.hpp"
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#include "scenes/sphere.hpp"
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namespace cbt::scenes {
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sphere::sphere() {
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m_start = std::chrono::steady_clock::now();
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}
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auto sphere::init() -> bool {
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if (!build_pipeline() || !build_post_pipeline()) {
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return false;
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}
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return true;
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}
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auto sphere::update(float) -> void {}
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auto sphere::render(int width, int height) -> void {
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auto now = std::chrono::steady_clock::now();
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auto elapsed = std::chrono::duration<float>(now - m_start).count();
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m_rt.resize(width, height);
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glViewport(0, 0, width, height);
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// Step 1: Render scene to texture (offscreen pass)
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m_rt.bind();
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glClearColor(0.15f, 0.15f, 0.2f, 1.0f);
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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auto aspect = float(width) / float(height);
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auto proj = glm::perspective(glm::radians(45.0f), aspect, 0.1f, 100.0f);
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auto view = glm::translate(glm::mat4{1.0f}, glm::vec3{0.0f, 0.0f, -4.0f});
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auto model = glm::rotate(glm::mat4{1.0f}, elapsed, glm::vec3{1.0f, 0.3f, 0.2f});
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m_scene_pipeline.draw(model, view, proj);
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m_rt.unbind();
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// Reset viewport for screen pass (RT bind changed it)
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glViewport(0, 0, width, height);
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// Step 2: Post-processing step (sample RT texture, apply effect, render to screen)
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glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
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glClear(GL_COLOR_BUFFER_BIT);
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m_post_pipeline.bind_texture("u_texture", m_rt.color_id(), 0);
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m_post_pipeline.draw(glm::mat4{1.0f}, glm::mat4{1.0f}, glm::mat4{1.0f});
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}
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auto sphere::build_pipeline() -> bool {
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char const* vert_src = R"glsl(
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#version 410 core
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layout(location = 0) in vec3 a_pos;
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layout(location = 1) in vec3 a_normal;
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layout(location = 2) in vec2 a_uv;
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layout(location = 3) in vec3 a_color;
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uniform mat4 u_model;
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uniform mat4 u_view;
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uniform mat4 u_proj;
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out vec3 v_normal;
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out vec3 v_world_pos;
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out vec2 v_uv;
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out vec3 v_color;
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void main() {
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gl_Position = u_proj * u_view * u_model * vec4(a_pos, 1.0);
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v_normal = mat3(u_model) * a_normal;
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v_world_pos = (u_model * vec4(a_pos, 1.0)).xyz;
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v_uv = a_uv;
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v_color = a_color;
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}
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)glsl";
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char const* frag_src = R"glsl(
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#version 410 core
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in vec3 v_normal;
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in vec3 v_world_pos;
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in vec2 v_uv;
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in vec3 v_color;
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out vec4 frag_color;
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void main() {
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vec3 light_dir = normalize(vec3(1.0, 1.0, 2.0));
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vec3 normal = normalize(v_normal);
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float diff = max(dot(normal, light_dir), 0.0);
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vec3 ambient = vec3(0.2);
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vec3 result = (ambient + diff * 0.8) * v_color;
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frag_color = vec4(result, 1.0);
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}
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)glsl";
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struct vertex {
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glm::vec3 position;
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glm::vec3 normal;
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glm::vec2 uv;
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glm::vec3 color;
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};
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std::uint32_t const div = 32;
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std::vector<vertex> vertices;
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std::vector<std::uint32_t> indices;
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// Distinct colors for each cube face so seams are visible
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glm::vec3 const face_colors[6] = {
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{1.0f, 0.2f, 0.2f}, // +X red
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{0.2f, 1.0f, 0.2f}, // -X green
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{0.2f, 0.2f, 1.0f}, // +Y blue
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{1.0f, 1.0f, 0.2f}, // -Y yellow
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{1.0f, 0.2f, 1.0f}, // +Z magenta
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{0.2f, 1.0f, 1.0f}, // -Z cyan
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};
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// Generate 6 cube faces, each with div x div vertices
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auto add_face = [&](glm::vec3 const& center, glm::vec3 const& u_axis,
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glm::vec3 const& v_axis, std::uint32_t face_idx) -> void {
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for (std::uint32_t i = 0; i < div; ++i) {
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for (std::uint32_t j = 0; j < div; ++j) {
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float const s = float(i) / float(div - 1) * 2.0f - 1.0f;
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float const t = float(j) / float(div - 1) * 2.0f - 1.0f;
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// Position on cube face
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glm::vec3 pos = center + u_axis * s + v_axis * t;
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// FIX: normalize to project onto unit sphere
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// (the original nrz.cpp used a broken formula with p=50.0)
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float const len = glm::length(pos);
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glm::vec3 normal = pos / len;
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vertices.push_back({normal, normal, {float(i) / float(div - 1), float(j) / float(div - 1)}, face_colors[face_idx]});
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}
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}
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};
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// +X face (right)
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add_face(glm::vec3{1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 1.0f, 0.0f}, glm::vec3{0.0f, 0.0f, 1.0f}, 0);
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// -X face (left)
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add_face(glm::vec3{-1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 1.0f, 0.0f}, glm::vec3{0.0f, 0.0f, -1.0f}, 1);
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// +Y face (top)
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add_face(glm::vec3{0.0f, 1.0f, 0.0f}, glm::vec3{1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 0.0f, -1.0f}, 2);
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// -Y face (bottom)
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add_face(glm::vec3{0.0f, -1.0f, 0.0f}, glm::vec3{1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 0.0f, 1.0f}, 3);
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// +Z face (front)
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add_face(glm::vec3{0.0f, 0.0f, 1.0f}, glm::vec3{1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 1.0f, 0.0f}, 4);
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// -Z face (back)
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add_face(glm::vec3{0.0f, 0.0f, -1.0f}, glm::vec3{-1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 1.0f, 0.0f}, 5);
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// Generate indices for each face
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std::uint32_t offset = 0;
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for (std::uint32_t face = 0; face < 6; ++face) {
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for (std::uint32_t i = 0; i < div - 1; ++i) {
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for (std::uint32_t j = 0; j < div - 1; ++j) {
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std::uint32_t const a = offset + i * div + j;
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std::uint32_t const b = offset + (i + 1) * div + j;
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std::uint32_t const c = offset + (i + 1) * div + j + 1;
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std::uint32_t const d = offset + i * div + j + 1;
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// Two triangles per quad (consistent winding)
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indices.push_back(a);
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indices.push_back(b);
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indices.push_back(d);
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indices.push_back(b);
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indices.push_back(c);
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indices.push_back(d);
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}
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}
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offset += div * div;
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}
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gfx::pipeline_desc desc{
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.vertex_data = std::as_bytes(std::span{vertices}),
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.index_data = std::as_bytes(std::span{indices}),
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.attributes = {
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{.location = 0, .num_components = 3, .offset = 0},
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{.location = 1, .num_components = 3, .offset = 12},
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{.location = 2, .num_components = 2, .offset = 24},
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{.location = 3, .num_components = 3, .offset = 32},
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},
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.vertex_stride = sizeof(vertex),
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.vertex_shader_src = vert_src,
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.fragment_shader_src = frag_src,
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.depth_test = true,
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.primitive = gfx::primitive_type::triangles,
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.index_type_ = gfx::index_type::uint32
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};
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m_scene_pipeline = gfx::pipeline{desc};
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return m_scene_pipeline.valid();
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}
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auto sphere::build_post_pipeline() -> bool {
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char const* post_vert = R"glsl(
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#version 410 core
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layout(location = 0) in vec2 a_pos;
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layout(location = 1) in vec2 a_uv;
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out vec2 v_uv;
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void main() {
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gl_Position = vec4(a_pos, 0.0, 1.0);
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v_uv = a_uv;
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}
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)glsl";
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char const* post_frag = R"glsl(
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#version 410 core
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in vec2 v_uv;
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uniform sampler2D u_texture;
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out vec4 frag_color;
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void main() {
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vec3 col = texture(u_texture, v_uv).rgb;
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// simple processing: vignette only (preserves original colors from sphere faces)
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float vig = 1.0 - length(v_uv * 2.0 - 1.0) * 0.5;
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frag_color = vec4(col * vig, 1.0);
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}
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)glsl";
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struct fs_vertex {
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glm::vec2 pos;
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glm::vec2 uv;
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};
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std::array<fs_vertex, 4> qverts = {{
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{{-1.0f, -1.0f}, {0.0f, 0.0f}},
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{{ 1.0f, -1.0f}, {1.0f, 0.0f}},
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{{ 1.0f, 1.0f}, {1.0f, 1.0f}},
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{{-1.0f, 1.0f}, {0.0f, 1.0f}},
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}};
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std::array<std::uint32_t, 6> qinds = {0, 1, 2, 0, 2, 3};
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gfx::pipeline_desc desc{
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.vertex_data = std::as_bytes(std::span{qverts}),
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.index_data = std::as_bytes(std::span{qinds}),
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.attributes = {
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{.location = 0, .num_components = 2, .offset = 0},
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{.location = 1, .num_components = 2, .offset = 8},
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},
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.vertex_stride = sizeof(fs_vertex),
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.vertex_shader_src = post_vert,
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.fragment_shader_src = post_frag,
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.depth_test = false,
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.primitive = gfx::primitive_type::triangles,
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.index_type_ = gfx::index_type::uint32
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};
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m_post_pipeline = gfx::pipeline{desc};
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return m_post_pipeline.valid();
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}
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}
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