Implement sound buffer texture

Texture channel 0 has a 512x2 texture with audio samples. For now,
fill it with dummy data (ascending slope), so we can see some
output.

Signed-off-by: David Oberhollenzer <goliath@infraroot.at>

shader.c

@@ -31,6 +31,7 @@ static const char *frag_src_pre =
 "uniform vec4 iDate;\n"
 "uniform float iSampleRate;\n"
 "uniform vec3 iChannelResolution[4];\n"
+"uniform sampler2D iChannel0;"
 "\n";
 
 static const char *frag_src_post =

shadermeh.c

@@ -20,6 +20,9 @@ static GLfloat vertex_buffer[] = {
 	 1.0f,  1.0f, 1.0f,
 };
 
+static GLubyte audio_buffer[AUDIO_SAMPLES * AUDIO_CHANNELS];
+static float audio_sample_data[AUDIO_SAMPLES];
+
 static double diff_timespec(const struct timespec *time1,
 			    const struct timespec *time0)
 {
@@ -72,10 +75,11 @@ static const struct option long_opts[] = {
  	{ "height", required_argument, NULL, 'h' },
 	{ "shader", required_argument, NULL, 's' },
 	{ "to-stdout", no_argument, NULL, 'S' },
+	{ "stdin-audio", no_argument, NULL, 'a' },
 	{ NULL, 0, NULL, 0 },
 };
 
-static const char *short_opts = "w:h:s:S";
+static const char *short_opts = "w:h:s:Sa";
 
 static const char *usage_str =
 "shadermeh OPTIONS...\n"
@@ -85,21 +89,23 @@ static const char *usage_str =
 "  --width, -w <pixels>\n"
 "  --height, -h <pixels>\n"
 "\n"
-"  --to-stdout, -S\n"
+"  --to-stdout, -S              Poop raw RGB24 frames to stdout (blocking)\n"
+"  --stdin-audio, -a            Read raw PCM audio from stdin (non-blocking)\n"
 "\n"
 "  --shader, -s <shader file>\n"
 "\n";
 
 int main(int argc, char **argv)
 {
+	GLuint vao, vbo, fbo, fbo_tex, sound_tex, sampler_sound;
 	GLuint u_iResolution, u_iTime, u_iTimeDelta, u_iFrame;
 	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 have_audio = false;
 	bool to_stdout = false;
 	window *wnd;
 	int i;
@@ -126,6 +132,9 @@ int main(int argc, char **argv)
 		case 'S':
 			to_stdout = true;
 			break;
+		case 'a':
+			have_audio = true;
+			break;
 		default:
 			fputs(usage_str, stderr);
 			return EXIT_FAILURE;
@@ -222,6 +231,22 @@ int main(int argc, char **argv)
 
 	glUniform3f(u_iResolution, width, height, 0.0f);
 
+	glUniform1i(glGetUniformLocation(prog, "iChannel0"), 0);
+
+	/************************* textures *************************/
+	glGenTextures(1, &sound_tex);
+
+	glBindTexture(GL_TEXTURE_2D, sound_tex);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_R8,
+		     AUDIO_SAMPLES, AUDIO_CHANNELS, 0,
+		     GL_RED, GL_UNSIGNED_BYTE, audio_buffer);
+	glBindTexture(GL_TEXTURE_2D, 0);
+
+	glGenSamplers(1, &sampler_sound);
+	glSamplerParameteri(sampler_sound, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	glSamplerParameteri(sampler_sound, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glBindSampler(0, sampler_sound);
+
 	/******************** framebuffer object ********************/
 	if (to_stdout) {
 		glGenFramebuffers(1, &fbo);
@@ -242,6 +267,10 @@ int main(int argc, char **argv)
 	}
 
 	/******************** drawing loop ********************/
+	for (i = 0; i < AUDIO_SAMPLES; ++i) {
+		audio_sample_data[i] = (float)i / (float)AUDIO_SAMPLES;
+	}
+
 	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
 
 	while (to_stdout || window_handle_events()) {
@@ -252,7 +281,24 @@ int main(int argc, char **argv)
 			glBindFramebuffer(GL_FRAMEBUFFER, fbo);
 
 		glClear(GL_COLOR_BUFFER_BIT);
+
+		if (have_audio) {
+			glBindTexture(GL_TEXTURE_2D, sound_tex);
+
+			for (i = 0; i < AUDIO_SAMPLES; ++i) {
+				audio_buffer[i] = 255.0f * audio_sample_data[i];
+
+				audio_buffer[AUDIO_SAMPLES + i] =
+					audio_buffer[i];
+			}
+
+			glTexImage2D(GL_TEXTURE_2D, 0, GL_R8,
+				     AUDIO_SAMPLES, AUDIO_CHANNELS, 0,
+				     GL_RED, GL_UNSIGNED_BYTE, audio_buffer);
+		}
+
 		glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+		glBindTexture(GL_TEXTURE_2D, 0);
 
 		if (to_stdout) {
 			glFlush();
@@ -291,6 +337,9 @@ int main(int argc, char **argv)
 	}
 
 	/******************** cleanup ********************/
+	glDeleteTextures(1, &sound_tex);
+	glDeleteSamplers(1, &sampler_sound);
+
 	if (to_stdout) {
 		glBindFramebuffer(GL_FRAMEBUFFER, 0);
 		glDeleteFramebuffers(1, &fbo);

shadermeh.h

@@ -25,6 +25,9 @@
 #include <errno.h>
 #include <time.h>
 
+#define AUDIO_SAMPLES (512)
+#define AUDIO_CHANNELS (2)
+
 typedef struct {
 	Window wnd;
 	GLXContext gl;

shaders/osci.frag

@@ -0,0 +1,40 @@
+// Created by inigo quilez - iq/2013
+// https://www.youtube.com/c/InigoQuilez
+// https://iquilezles.org/
+
+
+// See also:
+//
+// Input - Keyboard    : https://www.shadertoy.com/view/lsXGzf
+// Input - Microphone  : https://www.shadertoy.com/view/llSGDh
+// Input - Mouse       : https://www.shadertoy.com/view/Mss3zH
+// Input - Sound       : https://www.shadertoy.com/view/Xds3Rr
+// Input - SoundCloud  : https://www.shadertoy.com/view/MsdGzn
+// Input - Time        : https://www.shadertoy.com/view/lsXGz8
+// Input - TimeDelta   : https://www.shadertoy.com/view/lsKGWV
+// Inout - 3D Texture  : https://www.shadertoy.com/view/4llcR4
+
+
+void mainImage( out vec4 fragColor, in vec2 fragCoord )
+{
+	// create pixel coordinates
+	vec2 uv = fragCoord.xy / iResolution.xy;
+
+	// the sound texture is 512x2
+	int tx = int(uv.x * 512.0);
+
+	// first row is frequency data (48Khz/4 in 512 texels, meaning 23 Hz per texel)
+	float fft  = texelFetch( iChannel0, ivec2(tx,0), 0 ).x;
+
+	// second row is the sound wave, one texel is one mono sample
+	float wave = texelFetch( iChannel0, ivec2(tx,1), 0 ).x;
+
+	// convert frequency to colors
+	vec3 col = vec3( fft, 4.0*fft*(1.0-fft), 1.0-fft ) * fft;
+
+	// add wave form on top
+	col += 1.0 -  smoothstep(0.0, 0.15, abs(wave - uv.y));
+
+	// output final color
+	fragColor = vec4(col,1.0);
+}