Add glslwrite tool and some examples

.gitignore

@@ -1 +1,2 @@
 glslview
+glslwrite

Makefile

@@ -1,2 +1,7 @@
+all : glslview glslwrite
+
 glslview : glslview.c
 	gcc -o glslview glslview.c -lSDL2 -lGL -lGLEW -Wall
+
+glslwrite : glslwrite.c
+	gcc -o glslwrite glslwrite.c -lSDL2 -lpng -lGL -lGLEW -Wall

examples/polygon.frag

@@ -0,0 +1,54 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+const float PI = 3.14159265358979323846;
+
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float poly(float n, vec2 m, float r, float rt, vec2 p) {
+        vec2 diff = (m - p) * rot(rt);
+        float d = length(diff);
+        float alpha = PI / n;
+        float gamma = mod(abs(atan(diff.x, diff.y)), alpha*2);
+
+        if (gamma > alpha)
+                gamma -= 2*alpha;
+
+        float r2 = r * cos(alpha) / cos(gamma);
+
+        return clamp((r2 - d)*sharpness, 0.0, 1.0);
+}
+
+float poly_d(float n, vec2 m, float r, float rt, vec2 p) {
+        return poly(n, m, r, rt, p) - poly(n, m, r - 1/sharpness, rt, p);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float scene = 0;
+
+        float c;
+
+        c = poly_d(5 - 3*cos(time/1000), vec2(0, 0), 0.5, PI * time/1000, p);
+        scene = abs(scene - c);
+
+        c = poly_d(5 - 3*cos(time/1000), vec2(0, 0), 0.5, -PI * time/1000, p);
+        scene = abs(scene - c);
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

examples/snail.frag

@@ -0,0 +1,41 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float circle(vec2 m, float r, vec2 p) {
+        vec2 diff = m - p;
+        float d = sqrt(dot(diff, diff));
+
+        return clamp((r - d)*sharpness, 0.0, 1.0);
+}
+
+float circle_d(vec2 m, float r, vec2 p) {
+        return circle(m, r, p) - circle(m, r - 1/sharpness, p);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float scene = 0;
+
+        for (int i = 1; i <= 50; i++) {
+                float c = circle_d(vec2(0.5, 0) * rot(time/500/i), 0.1 + 0.005*i, p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

examples/square-in-circle.frag

@@ -0,0 +1,66 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+const float PI = 3.14159265358979323846;
+
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float circle(vec2 m, float r, vec2 p) {
+        vec2 diff = m - p;
+        float d = sqrt(dot(diff, diff));
+
+        return clamp((r - d)*sharpness, 0.0, 1.0);
+}
+
+float circle_d(vec2 m, float r, vec2 p) {
+        return circle(m, r, p) - circle(m, r - 1/sharpness, p);
+}
+
+float square(vec2 m, float a, float r, vec2 p) {
+        vec2 diff = abs((m - p) * rot(r));
+        float d = max(diff.x, diff.y);
+
+        return clamp((a - d)*sharpness, 0.0, 1.0);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float scene = 0;
+
+        int n = 20;
+        float b = 1;
+        float alpha = 0;
+        for (int i = 0; i < n; i++) {
+                float c;
+
+                c = circle_d(vec2(0, 0), b, p);
+                scene = abs(scene - c);
+
+                float delta = mod(time/5000, PI/2);
+                alpha = mod(alpha + delta, PI/2);
+                b /= sqrt(2);
+
+                c = square(vec2(0, 0), b, alpha, p);
+                scene = abs(scene - c);
+
+                c = square(vec2(0, 0), b, -alpha, p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

examples/square-in-square.frag

@@ -0,0 +1,74 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+const float PI = 3.14159265358979323846;
+
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float circle(vec2 m, float r, vec2 p) {
+        vec2 diff = m - p;
+        float d = sqrt(dot(diff, diff));
+
+        return clamp((r - d)*sharpness, 0.0, 1.0);
+}
+
+float circle_d(vec2 m, float r, vec2 p) {
+        return circle(m, r, p) - circle(m, r - 1/sharpness, p);
+}
+
+float square(vec2 m, float a, float r, vec2 p) {
+        vec2 diff = abs((m - p) * rot(r));
+        float d = max(diff.x, diff.y);
+
+        return clamp((a - d)*sharpness, 0.0, 1.0);
+}
+
+float square_d(vec2 m, float a, float r, vec2 p) {
+        return square(m, a, r, p) - square(m, a - 1/sharpness, r, p);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float scene = 0;
+
+        int n = 20;
+        float b = 1;
+        float alpha = 0;
+        for (int i = 0; i < n; i++) {
+                float delta = mod(time/5000, PI/2);
+                alpha = mod(alpha + delta, PI/2);
+                b /= (sin(delta) + cos(delta));
+
+                float c = square(vec2(0, 0), b, alpha, p);
+                scene = abs(scene - c);
+        }
+
+
+        b = 1;
+        alpha = 0;
+        for (int i = 0; i < n; i++) {
+                float delta = mod(-time/5000, PI/2);
+                alpha = mod(alpha + delta, PI/2);
+                b /= (sin(delta) + cos(delta));
+
+                float c = square(vec2(0, 0), b, alpha, p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

examples/square-ring.frag

@@ -0,0 +1,41 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+const float PI = 3.14159265358979323846;
+
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float square(vec2 m, float a, float r, vec2 p) {
+        vec2 diff = abs((m - p) * rot(r));
+        float d = max(diff.x, diff.y);
+
+        return clamp((a - d)*sharpness, 0.0, 1.0);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float scene = 0;
+
+        int n = 10;
+        for (int i = 1; i <= n; i++) {
+                float c = square(vec2(0, 0), 0.5, PI/2*i/n - time/500, p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

examples/square-ring2.frag

@@ -0,0 +1,47 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+const float PI = 3.14159265358979323846;
+
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float square(vec2 m, float a, float r, vec2 p) {
+        vec2 diff = abs((m - p) * rot(r));
+        float d = max(diff.x, diff.y);
+
+        return clamp((a - d)*sharpness, 0.0, 1.0);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float scene = 0;
+
+        int n = 5;
+        for (int i = 1; i <= n; i++) {
+                float c = square(vec2(0, 0), 0.5, PI/2*i/n - time/3000, p);
+                scene = abs(scene - c);
+        }
+
+        n = 5;
+        for (int i = 1; i <= n; i++) {
+                float c = square(vec2(0, 0), 0.5, PI/2*i/n + time/3000, p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

examples/squares.frag

@@ -0,0 +1,42 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 500;
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float square(vec2 m, float a, float r, vec2 p) {
+        vec2 diff = abs((m - p) * rot(r));
+        float d = max(diff.x, diff.y);
+
+        return clamp((a - d)*sharpness, 0.0, 1.0);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float a = atan(p.x, p.y);
+
+        float x = mod(p.x, 0.1);
+        float y = mod(p.y, 0.1);
+
+        float scene = 0;
+
+        for (int i = 1; i <= 50; i++) {
+                float c = square(vec2(0.5, 0) * rot(time/500/i), 0.1 + 0.005*i, time/500/i + time/(100*i), p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

examples/supersnail.frag

@@ -0,0 +1,37 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float circle(vec2 m, float r, vec2 p) {
+        vec2 diff = m - p;
+        float d = sqrt(dot(diff, diff));
+
+        return clamp((r - d)*sharpness, 0.0, 1.0);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float scene = 0;
+
+        for (int i = 1; i <= 100; i++) {
+                float c = circle(vec2(0.5, 0) * rot(time/200/i), 0.1 + 0.002*i, p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

examples/torus.frag

@@ -0,0 +1,41 @@
+#version 330
+
+out vec4 fragColor;
+
+uniform vec2 res;
+uniform float time;
+
+const float sharpness = 300;
+
+const float PI = 3.14159265358979323846;
+
+
+mat2 rot(float a) {
+        return mat2(
+                cos(a), -sin(a),
+                sin(a), cos(a)
+        );
+}
+
+float square(vec2 m, float a, float r, vec2 p) {
+        vec2 diff = abs((m - p) * rot(r));
+        float d = max(diff.x, diff.y);
+
+        return clamp((a - d)*sharpness, 0.0, 1.0);
+}
+
+void main(void) {
+        vec2 m = res/2;
+        float s = min(m.x, m.y);
+        vec2 p = (gl_FragCoord.xy - m) / s;
+
+        float scene = 0;
+
+        int n = 48;
+        for (int i = 1; i <= n; i++) {
+                float c = square(vec2(0.5, 0) * rot(PI/2*(time/8000 + 4.0*i/n)) * vec2(1, 0.5), 0.1, PI/2*(24.0*i/n - time/800), p);
+                scene = abs(scene - c);
+        }
+
+        fragColor = vec4(vec3(1, 1, 1) * scene, 1);
+}

glslview.c

@@ -13,7 +13,7 @@ static GLint time;
 static GLint res;
 
 
-char * readfile(const char *filename) {
+static char * readfile(const char *filename) {
         FILE *f = fopen(filename, "r");
         if (!f)
                 return NULL;
@@ -39,7 +39,7 @@ char * readfile(const char *filename) {
         return buffer;
 }
 
-void printShaderInfoLog(GLuint obj) {
+static void printShaderInfoLog(GLuint obj) {
         GLint length = 0;
 
         glGetShaderiv(obj, GL_INFO_LOG_LENGTH, &length);
@@ -52,7 +52,7 @@ void printShaderInfoLog(GLuint obj) {
         }
 }
 
-void printProgramInfoLog(GLuint obj) {
+static void printProgramInfoLog(GLuint obj) {
         GLint length = 0;
 
         glGetProgramiv(obj, GL_INFO_LOG_LENGTH, &length);
@@ -65,7 +65,7 @@ void printProgramInfoLog(GLuint obj) {
         }
 }
 
-void init(char *filename) {
+static void init(char *filename) {
         glewInit();
 
 	glDisable(GL_DEPTH_TEST);
@@ -96,7 +96,7 @@ void init(char *filename) {
 
 }
 
-void render(SDL_Window *window) {
+static void render(SDL_Window *window) {
         int width, height;
         SDL_GetWindowSize(window, &width, &height);
 

glslwrite.c

@@ -0,0 +1,204 @@
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <png.h>
+
+#include <GL/glew.h>
+
+#include <SDL2/SDL.h>
+#include <SDL2/SDL_opengl.h>
+
+
+
+static unsigned frame_time = 0;
+
+
+static GLint time_loc;
+static GLint res_loc;
+
+
+static char * readfile(const char *filename) {
+        FILE *f = fopen(filename, "r");
+        if (!f)
+                return NULL;
+
+        size_t size = 1024;
+        char *buffer = malloc(size+1);
+        size_t count = 0, r;
+
+        do {
+                if (count == size) {
+                        size *= 2;
+                        buffer = realloc(buffer, size+1);
+                }
+
+                r = fread(buffer+count, 1, size-count, f);
+                count += r;
+        } while (r);
+
+        fclose(f);
+
+        buffer[count] = 0;
+
+        return buffer;
+}
+
+static void printShaderInfoLog(GLuint obj) {
+        GLint length = 0;
+
+        glGetShaderiv(obj, GL_INFO_LOG_LENGTH, &length);
+
+        if(length > 0) {
+                char log[length];
+
+                glGetShaderInfoLog(obj, sizeof(log), NULL, log);
+                fprintf(stderr, "%s\n", log);
+        }
+}
+
+static void printProgramInfoLog(GLuint obj) {
+        GLint length = 0;
+
+        glGetProgramiv(obj, GL_INFO_LOG_LENGTH, &length);
+
+        if(length > 0) {
+                char log[length];
+
+                glGetProgramInfoLog(obj, sizeof(log), NULL, log);
+                fprintf(stderr, "%s\n", log);
+        }
+}
+
+static void init(char *filename) {
+        glewInit();
+
+	glDisable(GL_DEPTH_TEST);
+
+        char *shader = readfile(filename);
+        if (!shader) {
+                fprintf(stderr, "Error: unable to read '%s'\n", filename);
+                exit(1);
+        }
+
+        GLuint frag = glCreateShader(GL_FRAGMENT_SHADER);
+        glShaderSource(frag, 1, (const GLchar **)&shader, NULL);
+        glCompileShader(frag);
+        printShaderInfoLog(frag);
+
+        GLuint program = glCreateProgram();
+        glAttachShader(program, frag);
+
+        glLinkProgram(program);
+        printProgramInfoLog(program);
+
+        glBindFragDataLocation(program, 0, "fragColor");
+        time_loc = glGetUniformLocation(program, "time");
+        res_loc = glGetUniformLocation(program, "res");
+
+        glUseProgram(program);
+}
+
+static void savePNG(uint8_t *pixels, int width, int height, const char *output_dir) {
+        char filename[strlen(output_dir) + 20];
+        snprintf(filename, sizeof(filename), "%s/%010u.png", output_dir, frame_time);
+
+        FILE *f = fopen(filename, "wb");
+	if (!f) {
+                fprintf(stderr, "unable to open PNG file\n");
+                exit(1);
+        }
+
+	png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	if (!png_ptr) {
+                fprintf(stderr, "unable to open PNG file\n");
+                exit(1);
+        }
+
+        png_set_swap_alpha(png_ptr);
+
+	png_infop info_ptr = png_create_info_struct(png_ptr);
+	if (!info_ptr) {
+		fprintf(stderr, "unable to create PNG info struct\n");
+                exit(1);
+	}
+
+	if (setjmp(png_jmpbuf(png_ptr))) {
+		fprintf(stderr, "unable to write PNG file\n");
+                exit(1);
+	}
+
+	png_init_io(png_ptr, f);
+
+	png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA,
+		     PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+	uint8_t *row_pointers[height];
+	for (size_t i = 0; i < height; i++)
+		row_pointers[i] = &pixels[4*i*width];
+
+	png_set_rows(png_ptr, info_ptr, row_pointers);
+	png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
+
+	png_destroy_write_struct(&png_ptr, &info_ptr);
+	fclose(f);
+}
+
+static void render(SDL_Window *window, const char *output_dir) {
+        int width, height;
+        SDL_GetWindowSize(window, &width, &height);
+
+	glViewport(0, 0, (GLsizei)width, (GLsizei)height);
+
+        glUniform1f(time_loc, frame_time);
+        glUniform2f(res_loc, width, height);
+
+	glBegin(GL_QUADS);
+	glVertex2f(-1, -1);
+	glVertex2f(1, -1);
+	glVertex2f(1, 1);
+	glVertex2f(-1, 1);
+	glEnd();
+
+	SDL_GL_SwapWindow(window);
+
+        uint8_t pixels[width*height*4];
+        glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8, pixels);
+        savePNG(pixels, width, height, output_dir);
+
+        frame_time += 20;
+}
+
+
+int main(int argc, char *argv[]) {
+	bool running = true;
+
+        if (argc != 3) {
+                fprintf(stderr, "Usage: glslwrite <shader> <output directory>\n");
+                exit(1);
+        }
+
+	SDL_Init(SDL_INIT_VIDEO);
+
+	SDL_Window *window = SDL_CreateWindow("glslwrite", 0, 0, 800, 800, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
+        SDL_GL_CreateContext(window);
+
+        init(argv[1]);
+
+	while (running) {
+		SDL_Event e;
+
+		while( SDL_PollEvent(&e)) {
+			if(e.type == SDL_QUIT) {
+				running = false;
+                                break;
+			}
+		}
+
+		render(window, argv[2]);
+                //usleep(1);
+	}
+
+	return 0;
+}