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#include<fstream>
#include<cmath>
class Vertice
{
public:
float x, y, z;
unsigned char red, green, blue;
Vertice(float x, float y, float z, int red, int green, int blue)
{
this->x = x;
this->y = y;
this->z = z;
this->red = (unsigned char)red;
this->green = (unsigned char)green;
this->blue = (unsigned char)blue;
}
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;
Image(int imageWidth, int imageHeight)
{
this->imageWidth = imageWidth;
this->imageHeight = imageHeight;
pixels = new unsigned char[imageWidth * imageHeight * 3];
}
~Image()
{
delete[] pixels;
}
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;
}
}
//-------------------SCANLINE TRIANGLE RASTERISATION---------------------------
void fillFlatTopTriangle(Vertice* v1, Vertice* v2, Vertice* v3)
{
float invslope1 = (float)(v3->x - v1->x) / (float)(v3->y - v1->y);
float invslope2 = (float)(v3->x - v2->x) / (float)(v3->y - v2->y);
float curx1 = v3->x;
float curx2 = v3->x;
int cury1 = (int)ceil(v1->y - 0.5f);
int cury2 = (int)ceil(v3->y - 0.5f);
for (int i = cury2; i >= cury1; i--)
{
if(curx1 < curx2)
for (int j = (int)ceil(curx1 - 0.5f); j <= (int)ceil(curx2 - 0.5f); j++)
setPixel(j, i, 255, 0, 0);
else
for (int j = (int)ceil(curx2 - 0.5f); j <= (int)ceil(curx1 - 0.5f); j++)
setPixel(j, i, 255, 0, 0);
curx1 -= invslope1;
curx2 -= invslope2;
}
}
void fillFlatBottomTriangle(Vertice* v1, Vertice* v2, Vertice* v3)
{
float invslope1 = (float)(v2->x - v1->x) / (float)(v2->y - v1->y);
float invslope2 = (float)(v3->x - v1->x) / (float)(v3->y - v1->y);
float curx1 = v1->x;
float curx2 = v1->x;
int cury1 = (int)ceil(v1->y - 0.5f);
int cury2 = (int)ceil(v2->y - 0.5f);
for (int i = cury1; i <= cury2; i++)
{
if(curx1 < curx2)
for (int j = (int)ceil(curx1 - 0.5f); j <= (int)ceil(curx2 - 0.5f); j++)
setPixel(j, i, 255, 0, 0);
else
for (int j = (int)ceil(curx2 - 0.5f); j <= (int)ceil(curx1 - 0.5f); j++)
setPixel(j, i, 255, 0, 0);
curx1 += invslope1;
curx2 += invslope2;
}
}
void fillTriangle(Vertice* v1, Vertice* v2, Vertice* v3)
{
if (v1->y > v2->y)
std::swap(v1, v2);
if (v1->y > v3->y)
std::swap(v1, v3);
if (v2->y > v3->y)
std::swap(v2, v3);
if (v2->y == v3->y){
if(v2->x < v3->x)
std::swap(v2, v3);
fillFlatBottomTriangle(v1, v2, v3);
}
else if (v1->y == v2->y){
if(v1->x < v2->x)
std::swap(v1, v2);
fillFlatTopTriangle(v1, v2, v3);
}
else
{
Vertice v4(
(v1->x + (((float)(v2->y - v1->y) / (float)(v3->y - v1->y)) * (v3->x - v1->x))), v2->y, 0.0f, 0, 0, 0);
if(v1->x < v4.x){
fillFlatBottomTriangle(v1, v2, &v4);
fillFlatTopTriangle(v2, &v4, v3);
}
else{
fillFlatBottomTriangle(v1, &v4, v2);
fillFlatTopTriangle(&v4, v2, v3);
}
}
}
//-----------------------------------------------------------------------------
};
int main()
{
Image image(800, 600);
image.fillPixels(255, 255, 255);
Vertice a(0.2f, 0.5f, 0.0f, 255, 0, 0);
Vertice b(-0.5f, 0.0f, 0.0f, 0, 255, 0);
Vertice c(0.5f, -0.5f, 0.0f, 0, 0, 255);
a.fitToImage(image.imageWidth, image.imageHeight);
b.fitToImage(image.imageWidth, image.imageHeight);
c.fitToImage(image.imageWidth, image.imageHeight);
image.fillTriangle(&a, &b, &c);
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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