shadermeh/shadermeh.c

/* SPDX-License-Identifier: ISC */

/*
 * shadermeh.c
 *
 * Copyright (C) 2022 David Oberhollenzer <goliath@infraroot.at>
 */
#include "shadermeh.h"
#include <fcntl.h>
#include <errno.h>
#define HAVE_ARCH_STRUCT_FLOCK
#include <linux/fcntl.h>

static GLfloat vertex_buffer[] = {
	-1.0f, -1.0f, 0.0f,	/* lower left corner */
	 1.0f,  1.0f, 1.0f,

	+1.0f, -1.0f, 0.0f,	/* lower right corner */
	 1.0f,  1.0f, 1.0f,

	-1.0f,  1.0f, 0.0f,	/* uper left corner */
	 1.0f,  1.0f, 1.0f,

	+1.0f, +1.0f, 0.0f,	/* upper right corner */
	 1.0f,  1.0f, 1.0f,
};

static double diff_timespec(const struct timespec *time1,
			    const struct timespec *time0)
{
	return (time1->tv_sec - time0->tv_sec)
		+ (time1->tv_nsec - time0->tv_nsec) / 1000000000.0;
}

static void convert_for_ffmpeg(const uint8_t *in, uint8_t *out,
			       size_t width, size_t height)
{
	size_t x, y;

	for (y = 0; y < height; ++y) {
		const uint8_t *src = in + y * width * 4;
		uint8_t *dst = out + (height - 1 - y) * width * 3;

		for (x = 0; x < width; ++x) {
			*(dst++) = *(src++);
			*(dst++) = *(src++);
			*(dst++) = *(src++);
			++src;
		}
	}
}

static int write_retry(int fd, const void *buffer, size_t size)
{
	while (size > 0) {
		int ret = write(fd, buffer, size);

		if (ret < 0) {
			if (errno == EINTR){
                                continue;
                        }else if(errno == EAGAIN){
                                perror("Output pipe probably has O_NONBLOCK "
                                        "set! Removing setting");
                                ret = fcntl(STDOUT_FILENO, F_SETFL,
                                        fcntl(STDOUT_FILENO,F_GETFL)
                                        &(~O_NONBLOCK));
				if(ret == -1){
					perror("Failed to set STDOUT blocking");
					return -1;
				}
                                continue;
                        }else{
                                perror("write");
                        }
                        return -1;
		}

		if (ret == 0)
			return -1;

		size -= ret;
		buffer = (const char *)buffer + ret;
	}

	return 0;
}

static const struct option long_opts[] = {
	{ "width", required_argument, NULL, 'w' },
 	{ "height", required_argument, NULL, 'h' },
	{ "shader", required_argument, NULL, 's' },
	{ "sampling-rate", required_argument, NULL, 'r' },
	{ "to-stdout", no_argument, NULL, 'S' },
	{ NULL, 0, NULL, 0 },
};

static const char *short_opts = "r:w:h:s:S";

static const char *usage_str =
"shadermeh OPTIONS...\n"
"\n"
"Possible options:\n"
"\n"
"  --width, -w <pixels>\n"
"  --height, -h <pixels>\n"
"  --sampling-rate, -r <sampling rate[Hz]>\n"
"\n"
"  --to-stdout, -S\n"
"\n"
"  --shader, -s <shader file>\n"
"\n";

#define SND_BUFFER_SIZE   512

int main(int argc, char **argv)
{
	GLuint u_iResolution, u_iTime, u_iTimeDelta, u_iFrame;
	GLfloat u_iSampleRate;
	struct timespec start, frame_start, frame_end;
	unsigned int width, height, iFrame = 0;
	void *fb32 = NULL, *fb24 = NULL;
	const char *shader_file = NULL;
	GLuint vao, vbo, fbo, fbo_tex;
	GLint major, minor, prog;
	float iTime, iTimeDelta;
	bool to_stdout = false;
	window *wnd;
	int i;
	unsigned int sampling_rate = 0; /* Leaving this at 0 disables audio 
	                                 * input 
					 */
	float in_samples[SND_BUFFER_SIZE];   /* Raw input floats from -1...1 */
	float norm_samples[SND_BUFFER_SIZE]; /* Normalized samples from 0...1 */

	/******************** parse options ************************/
	width = 800;
	height = 450;

	for (;;) {
		i = getopt_long(argc, argv, short_opts, long_opts, NULL);
		if (i == -1)
			break;

		switch (i) {
		case 'w':
			width = strtol(optarg, NULL, 10);
			break;
		case 'h':
			height = strtol(optarg, NULL, 10);
			break;
		case 's':
			shader_file = optarg;
			break;
		case 'r':
			sampling_rate = strtol(optarg, NULL, 10);
			break;
		case 'S':
			to_stdout = true;
			break;
		default:
			fputs(usage_str, stderr);
			return EXIT_FAILURE;
		}
	}

	if (!shader_file) {
		fputs(usage_str, stderr);
		fputs("No shader file specified!\n", stderr);
		return EXIT_FAILURE;
	}

	if (to_stdout) {
		fb32 = calloc(1, width * height * 4);
		if (!fb32) {
			perror("allocating scratch framebuffer");
			return EXIT_FAILURE;
		}

		fb24 = calloc(1, width * height * 3);
		if (!fb24) {
			perror("allocating scratch framebuffer");
			free(fb32);
			return EXIT_FAILURE;
		}
		if(!isatty(STDOUT_FILENO)){
			long old_pipe_size = fcntl(STDOUT_FILENO, F_GETPIPE_SZ);
			if(old_pipe_size < 0){
				perror("Failed to get stdout pipe size");
			}else{

				int psz = getpagesize();
				size_t frame_size = (width * height * 3);
				size_t frame_cnt = psz / frame_size;
				if((psz % frame_size) != 0){
					frame_cnt++;
				}
				size_t new_pipe_size = frame_size * frame_cnt;
				int fin_psz = fcntl(STDOUT_FILENO, F_SETPIPE_SZ, 
					new_pipe_size);
				if(fin_psz < 0){
					fprintf(stderr, "Failed to set STDOUT "
						"pipe size to %zu: %s\n", 
						new_pipe_size, strerror(errno));
				}else{
					fprintf(stderr, "stdout pipe size "
						"change from %li to %zu "
							"resulted in %i\n", 
							old_pipe_size, 
							new_pipe_size, 
							fin_psz);
				}
				/* A failure to change pipe size is not 
				 * catastrophic, beacause the application will 
				 * still perform as needed, just with a bigger 
				 * or smaller buffer. */
			}
		}
	}
	if (sampling_rate != 0 && !isatty(STDIN_FILENO)){
		fputs("Sampling rate specified and STDIN not a tty! "
			"You habe been warnded!\n", stderr);
	}

	/********** create window and make context current **********/
	wnd = window_create(width, height, "shader meh...");

	if (!wnd) {
		fputs("failed to create window", stderr);
		free(fb32);
		free(fb24);
		return EXIT_FAILURE;
	}

	window_make_current(wnd);
	window_set_vsync(wnd, 1);

	/******************** load entry points ********************/
	glewExperimental = GL_TRUE;

	if (glewInit() != GLEW_OK) {
		fputs("glewInit() error", stderr);
		window_destroy(wnd);
		free(fb32);
		free(fb24);
		return EXIT_FAILURE;
	}

	glGetIntegerv(GL_MAJOR_VERSION, &major);
	glGetIntegerv(GL_MINOR_VERSION, &minor);
	fprintf(stderr,"OpenGL version %d.%d\n", major, minor);

	/******************** initialization ********************/
	glViewport(0, 0, width, height);
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

	/* vertex buffer object & vertex array object */
	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	glGenBuffers(1, &vbo);
	glBindBuffer(GL_ARRAY_BUFFER, vbo);

	glBufferData(GL_ARRAY_BUFFER, sizeof(vertex_buffer),
		     vertex_buffer, GL_STATIC_DRAW);

	glEnableVertexAttribArray(0);
	glEnableVertexAttribArray(1);

	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 6, 0);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 6,
			      (GLvoid *)(3 * sizeof(GLfloat)));

	/* shader */
	prog = shader_program_load(shader_file);

	if (!shader_program_get_build_status(prog)) {
		shader_program_print_info_log(prog);
	}

	glUseProgram(prog);

	/* uniforms */
	u_iResolution = glGetUniformLocation(prog, "iResolution");
	u_iTime = glGetUniformLocation(prog, "iTime");
	u_iTimeDelta = glGetUniformLocation(prog, "iTimeDelta");
	u_iFrame = glGetUniformLocation(prog, "iFrame;");
	u_iSampleRate = glGetUniformLocation(prog, "iSampleRate");

	glUniform3f(u_iResolution, width, height, 0.0f);
	glUniform1f(u_iSampleRate, sampling_rate);

	clock_gettime(CLOCK_MONOTONIC_RAW, &start);

	/******************** framebuffer object ********************/
	if (to_stdout) {
		glGenFramebuffers(1, &fbo);
		glGenTextures(1, &fbo_tex);

		glBindTexture(GL_TEXTURE_2D, fbo_tex);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0,
			     GL_RGBA, GL_UNSIGNED_BYTE, NULL);

		glBindFramebuffer(GL_FRAMEBUFFER, fbo);
		glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
				     fbo_tex, 0);
	} else {
		window_show(wnd);
	}

	/******************** drawing loop ********************/
	while (to_stdout || window_handle_events()) {
		/* render image to FBO */
		clock_gettime(CLOCK_MONOTONIC_RAW, &frame_start);
		glClear(GL_COLOR_BUFFER_BIT);
		glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

		if (to_stdout) {
			glFlush();
		} else {
			window_swap_buffers(wnd);
		}

		/* get image from FBO, dump to stdout */
		if (to_stdout) {
			glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA,
				      GL_UNSIGNED_BYTE, fb32);

			convert_for_ffmpeg(fb32, fb24, width, height);

			if (write_retry(STDOUT_FILENO, fb24,
					width * height * 3)) {
				break;
			}
		}

		/* update timers */
		clock_gettime(CLOCK_MONOTONIC_RAW, &frame_end);

		iFrame += 1;
		iTimeDelta = diff_timespec(&frame_end, &frame_start);
		iTime = diff_timespec(&frame_end, &start);

		glUniform1f(u_iTimeDelta, iTimeDelta);
		glUniform1f(u_iTime, iTime);
		glUniform1ui(u_iFrame, iFrame);
	}

	/******************** cleanup ********************/
	glUseProgram(0);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glDeleteBuffers(1, &vbo);
	glBindVertexArray(0);
	glDeleteVertexArrays(1, &vao);
	glDeleteProgram(prog);

	if (to_stdout) {
		glBindFramebuffer(GL_FRAMEBUFFER, 0);
		glDeleteFramebuffers(1, &fbo);
		glDeleteTextures(1, &fbo_tex);
	}

	window_make_current(NULL);
	free(fb32);
	free(fb24);
	window_destroy(wnd);
	return EXIT_SUCCESS;
}