slint/examples/opengl_underlay/main.cpp
2025-09-09 07:07:49 +02:00

216 lines
8.5 KiB
C++

// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: MIT
#include "scene.h"
#include <cstdlib>
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <chrono>
#include <GLES2/gl2.h>
#include <GLES2/gl2platform.h>
static GLint compile_shader(GLuint program, GLuint shader_type, const GLchar *const *source)
{
auto shader_id = glCreateShader(shader_type);
glShaderSource(shader_id, 1, source, nullptr);
glCompileShader(shader_id);
GLint compiled = 0;
glGetShaderiv(shader_id, GL_COMPILE_STATUS, &compiled);
if (!compiled) {
GLint infoLen = 0;
glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &infoLen);
if (infoLen > 1) {
char *infoLog = reinterpret_cast<char *>(malloc(sizeof(char) * infoLen));
glGetShaderInfoLog(shader_id, infoLen, NULL, infoLog);
fprintf(stderr, "Error compiling %s shader:\n%s\n",
shader_type == GL_FRAGMENT_SHADER ? "fragment shader" : "vertex shader",
infoLog);
free(infoLog);
}
glDeleteShader(shader_id);
exit(1);
}
glAttachShader(program, shader_id);
return shader_id;
}
class OpenGLUnderlay
{
public:
OpenGLUnderlay(slint::ComponentWeakHandle<App> app) : app_weak(app) { }
void operator()(slint::RenderingState state, slint::GraphicsAPI)
{
switch (state) {
case slint::RenderingState::RenderingSetup:
setup();
break;
case slint::RenderingState::BeforeRendering:
if (auto app = app_weak.lock()) {
render((*app)->get_rotation_enabled());
(*app)->window().request_redraw();
}
break;
case slint::RenderingState::AfterRendering:
break;
case slint::RenderingState::RenderingTeardown:
teardown();
break;
}
}
private:
void setup()
{
program = glCreateProgram();
const GLchar *const fragment_shader =
"#version 100\n"
"#ifdef GL_FRAGMENT_PRECISION_HIGH\n"
" precision highp float;\n"
"#else\n"
" precision mediump float;\n"
"#endif\n"
"varying vec2 frag_position;\n"
"uniform float effect_time;\n"
"uniform float rotation_time;\n"
"const vec3 COLOR_BG_DARK = vec3(0.106, 0.106, 0.118);\n"
"const vec3 COLOR_DIAMOND = vec3(0.137, 0.149, 0.184);\n"
"const vec3 COLOR_ACCENT = vec3(0.12, 0.35, 0.75);\n"
"mat2 rotate(float angle) {\n"
" float s = sin(angle);\n"
" float c = cos(angle);\n"
" return mat2(c, -s, s, c);\n"
"}\n"
"void main() {\n"
" vec2 p_coords = frag_position;\n"
" float perspective_strength = 0.09;\n"
" float divisor = 1.0 + (-p_coords.y + 1.0) * perspective_strength;\n"
" p_coords /= divisor;\n"
" p_coords.y *= (1.0 + perspective_strength * 1.5);\n"
" const float MAX_ANGLE_DEGREES = 10.0;\n"
" float max_angle_rad = radians(MAX_ANGLE_DEGREES);\n"
" float oscillating_factor = sin(rotation_time / 1700.0);\n"
" float angle = oscillating_factor * max_angle_rad;\n"
" mat2 rotation_matrix = rotate(angle);\n"
" vec2 uv = rotation_matrix * p_coords * 6.0;\n"
" vec2 grid_id = floor(uv);\n"
" vec2 grid_uv = fract(uv) - 0.5;\n"
" float manhattan_dist = abs(grid_uv.x) + abs(grid_uv.y);\n"
" float wave_time = effect_time / 300.0;\n"
" float wave_offset = grid_id.x * 0.5 + grid_id.y * 0.15;\n"
" float accent_alpha = 0.5 + 0.5 * sin(wave_time + wave_offset);\n"
" accent_alpha = pow(accent_alpha, 2.0);\n"
" float diamond_size = 0.5;\n"
" float border_thickness = 0.03;\n"
" float diamond_fill_mask = 1.0 - smoothstep(diamond_size, diamond_size, "
"manhattan_dist);\n"
" float border_glow_mask = smoothstep(diamond_size - border_thickness, "
"diamond_size, manhattan_dist) -\n"
" smoothstep(diamond_size, diamond_size + "
"border_thickness, manhattan_dist);\n"
" vec3 final_color = COLOR_BG_DARK;\n"
" final_color = mix(final_color, COLOR_DIAMOND, diamond_fill_mask);\n"
" final_color = mix(final_color, COLOR_ACCENT, border_glow_mask * "
"accent_alpha);\n"
" gl_FragColor = vec4(final_color, 1.0);\n"
"}\n";
const GLchar *const vertex_shader = "#version 100\n"
"attribute vec2 position;\n"
"varying vec2 frag_position;\n"
"void main() {\n"
" frag_position = position;\n"
" gl_Position = vec4(position, 0.0, 1.0);\n"
"}\n";
auto fragment_shader_id = compile_shader(program, GL_FRAGMENT_SHADER, &fragment_shader);
auto vertex_shader_id = compile_shader(program, GL_VERTEX_SHADER, &vertex_shader);
GLint linked = 0;
glLinkProgram(program);
glGetProgramiv(program, GL_LINK_STATUS, &linked);
if (!linked) {
GLint infoLen = 0;
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLen);
if (infoLen > 1) {
char *infoLog = reinterpret_cast<char *>(malloc(sizeof(char) * infoLen));
glGetProgramInfoLog(program, infoLen, NULL, infoLog);
fprintf(stderr, "Error linking shader:\n%s\n", infoLog);
free(infoLog);
}
glDeleteProgram(program);
exit(1);
}
glDetachShader(program, fragment_shader_id);
glDetachShader(program, vertex_shader_id);
position_location = glGetAttribLocation(program, "position");
effect_time_location = glGetUniformLocation(program, "effect_time");
rotation_time_location = glGetUniformLocation(program, "rotation_time");
}
void render(bool enable_rotation)
{
glUseProgram(program);
const float vertices[] = { -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, 1.0, -1.0 };
glVertexAttribPointer(position_location, 2, GL_FLOAT, GL_FALSE, 0, vertices);
glEnableVertexAttribArray(position_location);
auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::steady_clock::now() - start_time);
glUniform1f(effect_time_location, elapsed.count());
// Handle the rotation and freezing of rotation via the UI toggle.
if (enable_rotation) {
if (!last_rotation_enabled) {
rotation_pause_offset = elapsed.count() - rotation_time;
}
rotation_time = elapsed.count() - rotation_pause_offset;
}
glUniform1f(rotation_time_location, rotation_time);
last_rotation_enabled = enable_rotation;
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glUseProgram(0);
}
void teardown() { glDeleteProgram(program); }
slint::ComponentWeakHandle<App> app_weak;
GLuint program = 0;
GLuint position_location = 0;
GLuint effect_time_location = 0;
GLuint rotation_time_location = 0;
std::chrono::time_point<std::chrono::steady_clock> start_time =
std::chrono::steady_clock::now();
double rotation_time = 0.0;
bool last_rotation_enabled = true;
double rotation_pause_offset = 0.0;
};
int main()
{
auto app = App::create();
if (auto error = app->window().set_rendering_notifier(OpenGLUnderlay(app))) {
if (*error == slint::SetRenderingNotifierError::Unsupported) {
fprintf(stderr,
"This example requires the use of a GL renderer. Please run with the "
"environment variable SLINT_BACKEND=winit-femtovg set.\n");
} else {
fprintf(stderr, "Unknown error calling set_rendering_notifier\n");
}
exit(EXIT_FAILURE);
}
app->run();
}