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main.cpp
217 lines (179 loc) · 4.84 KB
/
main.cpp
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#include <SDL2/SDL.h>
#define GL_GLEXT_PROTOTYPES
#include <GL/gl.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <cmath>
int main (int argc, char ** argv)
{
if (argc < 2)
{
std::cerr << "Usage: " << argv[0] << " <shader-file-1> [<shader-file-2> ...]" << std::endl;
return 1;
}
SDL_Init(SDL_INIT_VIDEO);
SDL_Window * window = SDL_CreateWindow("Shaders", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 600, 600, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
SDL_GLContext gl_context = SDL_GL_CreateContext(window);
GLenum shader_program = 0;
std::vector<std::string> saved_source;
GLint time_location = -1;
GLint mouse_location = -1;
auto reload = [&]()
{
char const * common = "varying vec2 position;\nuniform float time;uniform vec2 mouse;\n";
std::vector<std::string> source;
for (int i = 1; i < argc; ++i)
{
std::ifstream ifs(argv[i]);
std::ostringstream oss;
oss << ifs.rdbuf();
source.push_back(oss.str());
}
if (saved_source == source) return;
saved_source = source;
if (shader_program)
glDeleteProgram(shader_program);
shader_program = glCreateProgram();
GLenum vertex_shader = glCreateShader(GL_VERTEX_SHADER);
{
char const * s = "void main ( ) { gl_Position = gl_Vertex; position = (gl_ModelViewMatrix * gl_Vertex).xy; }\n";
char const * source[] = {common, s};
glShaderSource(vertex_shader, 2, source, nullptr);
}
glCompileShader(vertex_shader);
{
std::vector<char> log(4096);
GLsizei length;
glGetShaderInfoLog(vertex_shader, log.size(), &length, log.data());
std::cout << "Vertex shader compilation log:\n" << log.data() << std::flush;
}
GLenum fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
{
char const * s = "void main ( ) { gl_FragColor = color(); }";
std::vector<char const *> src;
src.push_back(common);
for (auto const & str : source)
src.push_back(str.c_str());
src.push_back(s);
glShaderSource(fragment_shader, src.size(), src.data(), nullptr);
}
glCompileShader(fragment_shader);
{
std::vector<char> log(4096);
GLsizei length;
glGetShaderInfoLog(fragment_shader, log.size(), &length, log.data());
std::cout << "Fragment shader compilation log:\n" << log.data() << std::flush;
}
glAttachShader(shader_program, vertex_shader);
glAttachShader(shader_program, fragment_shader);
glLinkProgram(shader_program);
glUseProgram(shader_program);
time_location = glGetUniformLocation(shader_program, "time");
mouse_location = glGetUniformLocation(shader_program, "mouse");
};
bool quit = false;
std::size_t frame_number = 0;
int width = 600, height = 600;
float screen_ratio = 1.0;
float mouse_x, mouse_y;
bool lbutton = false;
float cx = 0.0, cy = 0.0, scale = 1.0, rscale = 1.0;
while (!quit)
{
SDL_Event event;
while (SDL_PollEvent(&event)) switch (event.type)
{
case SDL_QUIT:
quit = true;
break;
case SDL_WINDOWEVENT:
switch (event.window.event)
{
case SDL_WINDOWEVENT_RESIZED:
width = event.window.data1;
height = event.window.data2;
glViewport(0, 0, width, height);
screen_ratio = static_cast<float>(width) / height;
break;
}
break;
case SDL_KEYDOWN:
switch (event.key.keysym.sym)
{
case SDLK_ESCAPE:
quit = true;
break;
case SDLK_l:
reload();
break;
case SDLK_r:
cx = 0.0;
cy = 0.0;
scale = 1.0;
rscale = 1.0;
break;
}
break;
case SDL_MOUSEBUTTONDOWN:
if (event.button.button == SDL_BUTTON_LEFT)
{
lbutton = true;
}
break;
case SDL_MOUSEBUTTONUP:
if (event.button.button == SDL_BUTTON_LEFT)
{
lbutton = false;
}
break;
case SDL_MOUSEMOTION:
{
float old_x = mouse_x;
float old_y = mouse_y;
mouse_x = (2.0 * event.motion.x - width) / width * screen_ratio;
mouse_y = -(2.0 * event.motion.y - height) / height;
if (lbutton)
{
cx -= (mouse_x - old_x) * scale;
cy -= (mouse_y - old_y) * scale;
}
break;
}
case SDL_MOUSEWHEEL:
{
scale *= std::pow(0.8, event.wheel.y);
break;
}
}
if (frame_number % 20 == 0)
reload();
if (time_location != -1)
glUniform1f(time_location, frame_number * 0.01f);
if (mouse_location != -1)
glUniform2f(mouse_location, mouse_x * rscale + cx, mouse_y * rscale + cy);
glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glTranslated(cx, cy, 0.0);
glScaled(rscale, rscale, 1.0);
glScaled(screen_ratio, 1.0, 1.0);
glBegin(GL_QUADS);
glVertex2d(-1.0, -1.0);
glVertex2d( 1.0, -1.0);
glVertex2d( 1.0, 1.0);
glVertex2d(-1.0, 1.0);
glEnd();
SDL_GL_SwapWindow(window);
++frame_number;
{
float old_rscale = rscale;
rscale += (scale - rscale) * 0.25;
cx += mouse_x * (old_rscale - rscale);
cy += mouse_y * (old_rscale - rscale);
}
}
SDL_GL_DeleteContext(gl_context);
SDL_DestroyWindow(window);
}