如何用C语言画一个高逼格的“心形“？

本文转自知乎：http://www.zhihu.com/question/20187195 Milo Yip大神的回答

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#include <stdio.h>

int main() {
	for (float y = 1.5f; y > -1.5f; y -= 0.1f) {
		for (float x = -1.5f; x < 1.5f; x += 0.05f) {
			float a = x * x + y * y - 1;
		putchar(a * a * a - x * x * y * y * y <= 0.0f ? '*' : ' ');
		}
		putchar('\n');
	}
}

  

 

  
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再来个有花纹的。（这其实是该函数的Level set）

#include <stdio.h>

int main() {
for (float y = 1.5f; y > -1.5f; y -= 0.1f) {
	for (float x = -1.5f; x < 1.5f; x += 0.05f) {
		float z = x * x + y * y - 1;
		float f = z * z * z - x * x * y * y * y;
		putchar(f <= 0.0f ? ".:-=+*#%@"[(int)(f * -8.0f)] : ' ');
	}

	putchar('\n');
	}
}

  

 

  
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简单使用迭代法求解，用Finite difference求法矢量，用wrapped diffuse着色。

#include <stdio.h>
#include <math.h>

float f(float x, float y, float z) 
{
	float a = x * x + 9.0f / 4.0f * y * y + z * z - 1;
	return a * a * a - x * x * z * z * z - 9.0f / 80.0f * y * y * z * z * z;
}

float h(float x, float z) {
	for (float y = 1.0f; y >= 0.0f; y -= 0.001f)
	if (f(x, y, z) <= 0.0f)
	return y;
	return 0.0f;
}

int main() {
	for (float z = 1.5f; z > -1.5f; z -= 0.05f) {
		for (float x = -1.5f; x < 1.5f; x += 0.025f) {
		float v = f(x, 0.0f, z);
		if (v <= 0.0f) {
			float y0 = h(x, z);
			float ny = 0.01f;
			float nx = h(x + ny, z) - y0;
			float nz = h(x, z + ny) - y0;
			float nd = 1.0f / sqrtf(nx * nx + ny * ny + nz * nz);
			float d = (nx + ny - nz) * nd * 0.5f + 0.5f;
			putchar(".:-=+*#%@"[(int)(d * 5.0f)]);
		} else
		putchar(' ');
		}

		putchar('\n');

	}
}

  

 

  
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「3D」版，简单使用迭代法求解，用Finite difference求法矢量，用wrapped diffuse着色。

#include <stdio.h>
#include <math.h>

float f(float x, float y, float z) 
{
	float a = x * x + 9.0f / 4.0f * y * y + z * z - 1;
	return a * a * a - x * x * z * z * z - 9.0f / 80.0f * y * y * z * z * z;
}


float h(float x, float z) {
	for (float y = 1.0f; y >= 0.0f; y -= 0.001f)
	if (f(x, y, z) <= 0.0f)
	return y;
	return 0.0f;
}


int main() {
	for (float z = 1.5f; z > -1.5f; z -= 0.05f) {
		for (float x = -1.5f; x < 1.5f; x += 0.025f) {
			float v = f(x, 0.0f, z);
			if (v <= 0.0f) {
				float y0 = h(x, z);
				float ny = 0.01f;
				float nx = h(x + ny, z) - y0;
				float nz = h(x, z + ny) - y0;
				float nd = 1.0f / sqrtf(nx * nx + ny * ny + nz * nz);
				float d = (nx + ny - nz) * nd * 0.5f + 0.5f;
				putchar(".:-=+*#%@"[(int)(d * 5.0f)]);
			} else
			putchar(' ');
		}
		putchar('\n');
	}
}

  

 

  
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把「3D版」输出至PPM文件，可以用Photoshop打开。另外降低了ny的值导致有超有趣的pattern，就保留下来吧。

#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#endif

#include <stdio.h>
#include <math.h>

float f(float x, float y, float z) {
	float a = x * x + 9.0f / 4.0f * y * y + z * z - 1;
	return a * a * a - x * x * z * z * z - 9.0f / 80.0f * y * y * z * z * z;
}

float h(float x, float z) {
	for (float y = 1.0f; y >= 0.0f; y -= 0.001f)
	if (f(x, y, z) <= 0.0f)
	return y;
	return 0.0f;
}

int main() {
	FILE* fp = fopen("heart.ppm", "w");
	int sw = 512, sh = 512;
	fprintf(fp, "P3\n%d %d\n255\n", sw, sh);
	for (int sy = 0; sy < sh; sy++) {
		float z = 1.5f - sy * 3.0f / sh;
		for (int sx = 0; sx < sw; sx++) {
			float x = sx * 3.0f / sw - 1.5f;
			float v = f(x, 0.0f, z);
			int r = 0;
			if (v <= 0.0f) {
				float y0 = h(x, z);
				float ny = 0.001f;
				float nx = h(x + ny, z) - y0;
				float nz = h(x, z + ny) - y0;
				float nd = 1.0f / sqrtf(nx * nx + ny * ny + nz * nz);
				float d = (nx + ny - nz) / sqrtf(3) * nd * 0.5f + 0.5f;
				r = (int)(d * 255.0f);
			}

			fprintf(fp, "%d 0 0 ", r);
		}
		fputc('\n', fp);
	}
	fclose(fp);
}

  

 

  
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文章来源: allen5g.blog.csdn.net，作者：CodeAllen的博客，版权归原作者所有，如需转载，请联系作者。

原文链接：allen5g.blog.csdn.net/article/details/87026407