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#include<fstream>
#include<cmath>
class Vertice
{
public:
float x, y, z;
float u, v;
Vertice(float x, float y, float z, float u, float v)
{
this->x = x;
this->y = y;
this->z = z;
this->u = u;
this->v = v;
}
void project()
{
x /= z;
y /= z;
u /= z;
v /= z;
z = 1.0f / z;
}
void fitToImage(int imageWidth, int imageHeight)
{
x = (x * (imageWidth / 2)) + (imageWidth / 2);
y = (-y * (imageHeight / 2)) + (imageHeight / 2);
}
};
class Image
{
public:
int imageWidth, imageHeight;
unsigned char* pixels;
float* zbuffer;
Image(int imageWidth, int imageHeight)
{
this->imageWidth = imageWidth;
this->imageHeight = imageHeight;
pixels = new unsigned char[imageWidth * imageHeight * 3];
zbuffer = new float[imageWidth * imageHeight];
for (int i = 0; i < imageWidth * imageHeight; i++)
zbuffer[i] = 1000.0f;
}
~Image()
{
delete[] pixels;
delete[] zbuffer;
}
void setPixel(int x, int y, int red, int green, int blue)
{
int help_var = ((y * imageWidth) + x) * 3;
pixels[help_var + 0] = (unsigned char)red;
pixels[help_var + 1] = (unsigned char)green;
pixels[help_var + 2] = (unsigned char)blue;
}
void fillPixels(int red, int green, int blue)
{
int help_var = imageWidth * imageHeight * 3;
for (int i = 0; i < help_var; i += 3) {
pixels[i + 0] = (unsigned char)red;
pixels[i + 1] = (unsigned char)green;
pixels[i + 2] = (unsigned char)blue;
}
}
void setZBufferAt(int x, int y, float value)
{
int hlp_var = ((y * imageWidth) + x);
zbuffer[hlp_var] = value;
}
float getZBufferAt(int x, int y)
{
int hlp_var = ((y * imageWidth) + x);
return zbuffer[hlp_var];
}
float edgeFunction(const Vertice& A, const Vertice& B, const Vertice& P)
{
return ((P.x - A.x)*(B.y - A.y) - (P.y - A.y)*(B.x - A.x));
}
void fillTriangleBarycentric(const Vertice& v0, const Vertice& v1, const Vertice& v2)
{
Vertice p(0.0f, 0.0f, 0.0f, 0.0f, 0.0f);
float area = edgeFunction(v0, v1, v2);
float edge0[2] = {v2.x - v1.x, v2.y - v1.y};
float edge1[2] = {v0.x - v2.x, v0.y - v2.y};
float edge2[2] = {v1.x - v0.x, v1.y - v0.y};
for (int x = 0; x < imageWidth; x++) {
for (int y = 0; y < imageHeight; y++) {
p.x = x + 0.5f; p.y = y + 0.5f;
float w0 = edgeFunction(v1, v2, p);
float w1 = edgeFunction(v2, v0, p);
float w2 = edgeFunction(v0, v1, p);
bool inside = true;
inside &= ((w0 == 0) ? ((edge0[1] == 0 && edge0[0] > 0) || edge0[1] > 0) : (w0 > 0));
inside &= ((w1 == 0) ? ((edge1[1] == 0 && edge1[0] > 0) || edge1[1] > 0) : (w1 > 0));
inside &= ((w2 == 0) ? ((edge2[1] == 0 && edge2[0] > 0) || edge2[1] > 0) : (w2 > 0));
if (inside) {
w0 /= area;
w1 /= area;
w2 /= area;
float z = 1.0f / (w0 * v0.z + w1 * v1.z + w2 * v2.z);
if (z < getZBufferAt(x, y)) {
setZBufferAt(x, y, z);
float u = (w0 * v0.u + w1 * v1.u + w2 * v2.u) * z;
float v = (w0 * v0.v + w1 * v1.v + w2 * v2.v) * z;
const float M = 8;
float p = (fmod(u * M, 1.0f) > 0.5f) ^ (fmod(v * M, 1.0f) < 0.5f);
int red = (int)(255.0f * p);
int green = (int)(255.0f * p);
int blue = (int)(255.0f * p);
setPixel(x, y, red, green, blue);
}
}
}
}
}
};
int main()
{
Image image(800, 600);
//image.fillPixels(255, 255, 255);
float sr = 90.0f, sg = 90.0f, sb = 130.0f;
float er = 0.0f, eg = 0.0f, eb = 80.0f;
float dr = ((er - sr) / 600.0f);
float dg = ((eg - sg) / 600.0f);
float db = ((eb - sb) / 600.0f);
for (int y = 0; y < 600; y++) {
sr += dr; sg += dg; sb += db;
for (int x = 0; x < 800; x++)
image.setPixel(x, y, (int)sr, (int)sg, (int)sb);
}
Vertice a(0.2f, 3.5f, 4.0f, 0.0f, 1.0f);
Vertice b(-0.8f, 0.0f, 1.0f, 0.0f, 0.0f);
Vertice c(1.6f, -1.6f, 2.0f, 1.0f, 0.0f);
Vertice d(2.0f, 2.0f, 3.0f, 0.0f, 1.0f);
Vertice e(-2.0f, -2.0f, 3.0f, 1.0f, 0.0f);
Vertice f(2.0f, -2.0f, 3.0f, 0.0f, 0.0f);
a.project();
b.project();
c.project();
d.project();
e.project();
f.project();
a.fitToImage(image.imageWidth, image.imageHeight);
b.fitToImage(image.imageWidth, image.imageHeight);
c.fitToImage(image.imageWidth, image.imageHeight);
d.fitToImage(image.imageWidth, image.imageHeight);
e.fitToImage(image.imageWidth, image.imageHeight);
f.fitToImage(image.imageWidth, image.imageHeight);
image.fillTriangleBarycentric(a, b, c);
image.fillTriangleBarycentric(d, e, f);
std::ofstream imageFile;
imageFile.open("./image.ppm");
imageFile << "P6 " << image.imageWidth << " " << image.imageHeight << " 255 ";
imageFile.write((char*)image.pixels, image.imageWidth * image.imageHeight * 3);
imageFile.close();
return 0;
}
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