# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1511045859 -7200
# Node ID 436f82447c44b5168919148c3aa7f23aeb6ed075
# Parent  6e849d7377ffcd7a60474014e12099b1bf4098e9
pan/scale and min orbit distance from point drawing

diff -r 6e849d7377ff -r 436f82447c44 mbrot.glsl
--- a/mbrot.glsl	Sat Nov 18 20:04:16 2017 +0200
+++ b/mbrot.glsl	Sun Nov 19 00:57:39 2017 +0200
@@ -3,6 +3,7 @@
 
 uniform float view_scale;
 uniform vec2 view_center;
+uniform vec2 seed;
 
 float mbrot_dist_point(in vec2 c, in vec2 p)
 {
@@ -14,7 +15,8 @@
 		float y = (z.x * z.y + z.x * z.y) + c.y;
 
 		z = vec2(x, y);
-		mindist_sq = min(mindist_sq, dot(z, z)); 
+		vec2 dir = z - seed;
+		mindist_sq = min(mindist_sq, dot(dir, dir)); 
 	}
 
 	return sqrt(mindist_sq);
@@ -22,7 +24,7 @@
 
 void main()
 {
-	vec2 c = gl_TexCoord[0].xy * view_scale - view_center;
+	vec2 c = gl_TexCoord[0].xy;
 	float m = 1.0 - mbrot_dist_point(c, vec2(0.0, 0.0));
 
 	gl_FragColor.rgb = vec3(m, m, m);
diff -r 6e849d7377ff -r 436f82447c44 src/main.c
--- a/src/main.c	Sat Nov 18 20:04:16 2017 +0200
+++ b/src/main.c	Sun Nov 19 00:57:39 2017 +0200
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
 #include <GL/glew.h>
 #include <GL/glut.h>
 #include "sdr.h"
@@ -8,14 +9,20 @@
 void cleanup(void);
 void disp(void);
 void reshape(int x, int y);
-void keyb(unsigned char key, int x, int y);
+void keydown(unsigned char key, int x, int y);
+void keyup(unsigned char key, int x, int y);
 void mouse(int bn, int st, int x, int y);
 void motion(int x, int y);
 
-static float aspect;
-static int mouse_x, mouse_y;
+static int win_width = 1280, win_height = 800;
+static float win_aspect;
+static int mouse_x = 640, mouse_y = 400;
 static unsigned int prog_mbrot;
 
+static float view_center[2] = {0.7, 0.0};
+static float view_scale = 1.2;
+
+
 int main(int argc, char **argv)
 {
 	glutInit(&argc, argv);
@@ -25,7 +32,8 @@
 
 	glutDisplayFunc(disp);
 	glutReshapeFunc(reshape);
-	glutKeyboardFunc(keyb);
+	glutKeyboardFunc(keydown);
+	glutKeyboardUpFunc(keyup);
 	glutMouseFunc(mouse);
 	glutMotionFunc(motion);
 
@@ -46,8 +54,6 @@
 	if(!(prog_mbrot = create_program_load("vertex.glsl", "mbrot.glsl"))) {
 		return -1;
 	}
-	set_uniform_float(prog_mbrot, "view_scale", 1.1);
-	set_uniform_float2(prog_mbrot, "view_center", 0.7, 0);
 	return 0;
 }
 
@@ -56,15 +62,35 @@
 	free_program(prog_mbrot);
 }
 
+void pixel_to_complex(float *res, float px, float py)
+{
+	float u = (2.0 * px / win_width - 1.0) * win_aspect;
+	float v = 2.0 * py / win_height - 1.0;
+	res[0] = u * view_scale - view_center[0];
+	res[1] = v * view_scale - view_center[1];
+}
+
 void disp(void)
 {
+	int i;
+	float seed[2];
+	static const float verts[][2] = {{-1, -1}, {1, -1}, {1, 1}, {-1, 1}};
+	static const float corners[][2] = {{0, 1}, {1, 1}, {1, 0}, {0, 0}};
+
+	pixel_to_complex(seed, mouse_x, mouse_y);
+
+	set_uniform_float2(prog_mbrot, "seed", seed[0], seed[1]);
+	set_uniform_float(prog_mbrot, "view_scale", view_scale);
+	set_uniform_float2(prog_mbrot, "view_center", view_center[0], view_center[1]);
 	glUseProgram(prog_mbrot);
 
 	glBegin(GL_QUADS);
-	glTexCoord2f(-aspect, 1); glVertex2f(-1, -1);
-	glTexCoord2f(aspect, 1); glVertex2f(1, -1);
-	glTexCoord2f(aspect, -1); glVertex2f(1, 1);
-	glTexCoord2f(-aspect, -1); glVertex2f(-1, 1);
+	for(i=0; i<4; i++) {
+		float bv[2];
+		pixel_to_complex(bv, (win_width - 1) * corners[i][0], (win_height - 1) * corners[i][1]);
+		glTexCoord2f(bv[0], bv[1]);
+		glVertex2f(verts[i][0], verts[i][1]);
+	}
 	glEnd();
 
 	glutSwapBuffers();
@@ -74,22 +100,76 @@
 {
 	glViewport(0, 0, x, y);
 
-	aspect = (float)x / (float)y;
+	win_aspect = (float)x / (float)y;
+	win_width = x;
+	win_height = y;
 }
 
-void keyb(unsigned char key, int x, int y)
+static int keystate[256];
+
+void keydown(unsigned char key, int x, int y)
 {
-	if(key == 27) {
+	static int fullscreen;
+	static int prev_width, prev_height;
+
+	switch(key) {
+	case 27:
 		exit(0);
+
+	case 'f':
+		fullscreen = !fullscreen;
+		if(fullscreen) {
+			prev_width = win_width;
+			prev_height = win_height;
+			glutFullScreen();
+		} else {
+			glutReshapeWindow(prev_width, prev_height);
+		}
+		break;
+
+	default:
+		break;
 	}
+	keystate[key] = 1;
 }
 
+void keyup(unsigned char key, int x, int y)
+{
+	keystate[key] = 0;
+}
+
+static int prev_x, prev_y;
+static int bnstate[8];
+
 void mouse(int bn, int st, int x, int y)
 {
+	prev_x = x;
+	prev_y = y;
+	bnstate[bn - GLUT_LEFT_BUTTON] = st == GLUT_DOWN ? 1 : 0;
 }
 
 void motion(int x, int y)
 {
-	mouse_x = x;
-	mouse_y = y;
+	int dx = x - prev_x;
+	int dy = y - prev_y;
+	prev_x = x;
+	prev_y = y;
+
+	if(!(dx | dy)) return;
+
+	if(bnstate[0]) {
+		if(keystate['s']) {
+			mouse_x = x;
+			mouse_y = y;
+		} else if(keystate['z']) {
+			float s = sqrt(view_scale);
+			view_scale += dy * 0.01 * s;
+			if(view_scale < 1e-8) view_scale = 1e-8;
+		} else {
+			float s = sqrt(view_scale);
+			view_center[0] += 0.01 * dx * s;
+			view_center[1] += 0.01 * dy * s;
+		}
+		glutPostRedisplay();
+	}
 }