Add a procedural fire example
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examples/fire.cpp
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326
examples/fire.cpp
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#include <psemek/app/app.hpp>
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#include <psemek/app/main.hpp>
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#include <psemek/gfx/mesh.hpp>
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#include <psemek/gfx/program.hpp>
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#include <psemek/gfx/texture.hpp>
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#include <psemek/geom/camera.hpp>
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#include <psemek/geom/math.hpp>
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#include <psemek/geom/rotation.hpp>
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#include <psemek/geom/scale.hpp>
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#include <psemek/geom/translation.hpp>
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#include <psemek/geom/easing.hpp>
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#include <psemek/geom/gradient.hpp>
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#include <psemek/pcg/random/device.hpp>
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#include <psemek/pcg/random/generator.hpp>
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#include <psemek/pcg/random/uniform_sphere.hpp>
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#include <psemek/pcg/perlin.hpp>
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#include <psemek/util/clock.hpp>
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using namespace psemek;
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static char const vertex_source[] =
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R"(#version 330
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uniform mat4 u_transform;
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uniform vec3 u_camera_pos;
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layout (location = 0) in vec4 in_position;
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layout (location = 1) in vec3 in_instance_pos;
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layout (location = 2) in vec3 in_instance_z;
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layout (location = 3) in float in_instance_size;
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layout (location = 4) in vec2 in_instance_noise_offset;
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out vec2 texcoord;
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out vec2 noise_offset;
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out float z;
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void main()
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{
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vec3 instance_y = u_camera_pos - in_instance_pos;
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instance_y -= dot(in_instance_z, instance_y) * in_instance_z;
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instance_y = -normalize(instance_y);
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vec3 instance_x = cross(instance_y, in_instance_z);
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mat4 transform;
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transform[0] = vec4(instance_x, 0.0);
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transform[1] = vec4(instance_y, 0.0);
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transform[2] = vec4(in_instance_z, 0.0);
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transform[3] = vec4(in_instance_pos, 1.0);
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gl_Position = u_transform * (transform * in_position);
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texcoord = in_position.xz * 0.5 + vec2(0.5, 0.5);
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noise_offset = in_instance_noise_offset;
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z = in_position.z;
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}
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)";
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static char const fragment_source[] =
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R"(#version 330
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uniform sampler2D u_texture;
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uniform sampler2D u_noise_texture;
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uniform float u_time;
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in vec2 texcoord;
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in vec2 noise_offset;
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in float z;
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out vec4 out_color;
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void main()
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{
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vec2 tc = texcoord + (2.0 * texture(u_noise_texture, texcoord + noise_offset * u_time).xy - vec2(1.0, 1.0)) * 0.1 * z;
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out_color = texture(u_texture, tc);
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}
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)";
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struct candle_renderer
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{
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candle_renderer();
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void add(geom::point<float, 3> const & pos, geom::vector<float, 3> const & dir, float size);
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void render(geom::camera const & camera, float time);
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private:
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struct candle
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{
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geom::point<float, 3> pos;
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geom::vector<float, 3> dir;
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float size;
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geom::vector<float, 2> noise_offset;
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};
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std::vector<candle> candles_;
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bool instances_need_update_ = false;
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gfx::program program_{vertex_source, fragment_source};
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gfx::instanced_mesh mesh_;
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gfx::texture_2d texture_;
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gfx::texture_2d noise_texture_;
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void update_instances();
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};
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candle_renderer::candle_renderer()
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{
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std::vector<geom::point<float, 3>> vertices;
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vertices.push_back({-1.f, 0.f, -1.f});
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vertices.push_back({ 1.f, 0.f, -1.f});
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vertices.push_back({ 1.f, 0.f, 1.f});
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vertices.push_back({-1.f, 0.f, -1.f});
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vertices.push_back({ 1.f, 0.f, 1.f});
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vertices.push_back({-1.f, 0.f, 1.f});
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mesh_.setup<geom::point<float, 3>, gfx::instanced<geom::point<float, 3>>, gfx::instanced<geom::vector<float, 3>>, gfx::instanced<float>, gfx::instanced<geom::vector<float, 2>>>();
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mesh_.load(vertices, gl::TRIANGLES);
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geom::vector<float, 4> c0 {1.f, 0.99f, 0.98f, 1.f};
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geom::vector<float, 4> c1 {1.f, 0.4f, 0.f, 0.75f};
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geom::vector<float, 4> c2 {c1[0], c1[1], c1[2], 0.f};
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geom::gradient<float> gy{
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std::make_pair(0.f, 0.f),
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geom::easing_type::quadratic_in,
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std::make_pair(1.f, 2.f),
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};
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geom::gradient<float, geom::vector<float, 4>> gc
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{
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std::make_pair(0.1f, c0),
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geom::easing_type::linear,
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std::pair{0.8f, c1},
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geom::easing_type::cubic,
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std::pair{1.2f, c2}
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};
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{
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gfx::pixmap_rgba pm({512, 512}, {0, 0, 0, 0});
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for (auto idx : pm.indices())
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{
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float x = 2.f * (idx[0] + 0.5f) / pm.width() - 1.f;
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float y = 2.f * (idx[1] + 0.5f) / pm.height() - 1.f;
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float d = 10.f;
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float size = 0.1f;
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if (y >= 0)
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{
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d = std::abs(x) / size + gy(y);
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}
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else
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{
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d = std::sqrt(x * x + y * y) / size;
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}
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pm(idx) = gfx::to_coloru8(gc(d));
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}
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texture_.load(pm);
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texture_.linear_filter();
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texture_.anisotropy();
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texture_.generate_mipmap();
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texture_.clamp();
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}
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{
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pcg::generator rng;
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pcg::uniform_sphere_vector_distribution<float, 2> d;
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util::array<geom::vector<float, 2>, 2> grad({16, 16});
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for (auto & v : grad) v = d(rng);
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pcg::perlin<float, 2> perlinx(grad, pcg::seamless);
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for (auto & v : grad) v = d(rng);
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pcg::perlin<float, 2> perliny(grad, pcg::seamless);
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gfx::basic_pixmap<geom::vector<std::uint8_t, 2>> pm({512, 512});
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for (auto idx : pm.indices())
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{
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float x = (0.5f + idx[0]) / pm.width();
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float y = (0.5f + idx[1]) / pm.height();
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pm(idx) = gfx::to_coloru8(geom::vector{perlinx({x, y}), perliny({x, y})});
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}
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noise_texture_.load(pm);
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noise_texture_.linear_filter();
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noise_texture_.anisotropy();
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noise_texture_.generate_mipmap();
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noise_texture_.repeat();
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}
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}
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void candle_renderer::add(geom::point<float, 3> const & pos, geom::vector<float, 3> const & dir, float size)
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{
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pcg::generator rng{pcg::random_device{}};
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pcg::uniform_sphere_vector_distribution<float, 2> d;
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geom::vector<float, 2> noise_offset;
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while (true)
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{
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noise_offset = d(rng);
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if (std::abs(noise_offset[0]) < 0.5f)
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break;
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}
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if (noise_offset[1] > 0.f)
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noise_offset[1] *= -1.f;
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candles_.push_back({pos, dir, size, noise_offset * 0.5f});
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instances_need_update_ = true;
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}
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void candle_renderer::render(geom::camera const & camera, float time)
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{
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if (instances_need_update_) update_instances();
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program_.bind();
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program_["u_transform"] = camera.transform();
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program_["u_camera_pos"] = camera.position();
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program_["u_texture"] = 0;
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program_["u_noise_texture"] = 1;
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program_["u_time"] = time;
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gl::ActiveTexture(gl::TEXTURE0);
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texture_.bind();
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gl::ActiveTexture(gl::TEXTURE1);
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noise_texture_.bind();
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(void)time;
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mesh_.draw();
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}
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void candle_renderer::update_instances()
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{
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struct instance
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{
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geom::point<float, 3> pos;
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geom::vector<float, 3> dir;
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float size;
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geom::vector<float, 2> noise_offset;
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};
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std::vector<instance> instances;
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instances.reserve(candles_.size());
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for (candle const & c: candles_)
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{
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instances.push_back({c.pos, c.dir, c.size, c.noise_offset});
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}
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mesh_.load_instance(instances);
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}
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struct fire_app
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: app::app
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{
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geom::spherical_camera camera;
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candle_renderer candles;
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util::clock<std::chrono::duration<float>> clock;
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float time = 0.f;
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fire_app()
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: app("Fire")
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{
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camera.fov_y = geom::rad(45.f);
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camera.near_clip = 0.01f;
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camera.far_clip = 1000.f;
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camera.target = {0.f, 0.f, 0.f};
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camera.elevation_angle = 0.f;
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camera.azimuthal_angle = 0.f;
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camera.distance = 4.f;
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candles.add({0.f, 0.f, 0.f}, {0.f, 0.f, 1.f}, 1.f);
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}
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void on_resize(int width, int height) override
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{
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app::on_resize(width, height);
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camera.set_fov(camera.fov_y, (1.f * width) / height);
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}
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void on_mouse_move(int x, int y, int dx, int dy) override
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{
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app::on_mouse_move(x, y, dx, dy);
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if (is_middle_button_down())
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{
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camera.azimuthal_angle -= dx * 0.01f;
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camera.elevation_angle += dy * 0.01f;
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}
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}
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void on_mouse_wheel(int delta) override
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{
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app::on_mouse_wheel(delta);
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camera.distance *= std::pow(0.8f, delta);
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}
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void update() override
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{
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if (!is_key_down(SDLK_SPACE))
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time += clock.restart().count();
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}
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void render() override
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{
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gl::ClearColor(0.f, 0.f, 0.f, 1.f);
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gl::Clear(gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT);
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gl::Enable(gl::BLEND);
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gl::BlendFunc(gl::SRC_ALPHA, gl::ONE_MINUS_SRC_ALPHA);
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candles.render(camera, time);
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}
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};
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int main()
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{
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return app::main<fire_app>();
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}
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