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basic2D.cpp
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basic2D.cpp
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#include "basic2D.h"
void drawLine(int x1,int y1,int x2,int y2,Color color)
{
if((x1<=WINDOW_X/2 && x1>=-WINDOW_X/2) && (y1<=WINDOW_Y/2 && y1>=-WINDOW_Y/2)){
float xdiff = (x2 - x1);
float ydiff = (y2 - y1);
if (xdiff == 0.0f && ydiff == 0.0f)
{
setPixel(x1, y1,color);
return;
}
if (fabs(xdiff) > fabs(ydiff))
{
float xmin, xmax;
// set xmin to the lower x value given
// and xmax to the higher value
if (x1 < x2)
{
xmin = x1;
xmax = x2;
}
else
{
xmin = x2;
xmax = x1;
}
// draw line in terms of y slope
float slope = ydiff / xdiff;
for (float x = xmin; x <= xmax; x += 1.0f)
{
float y = y1 + ((x - x1) * slope);
setPixel(x, y,color);
}
}
else
{
float ymin, ymax;
// set ymin to the lower y value given
// and ymax to the higher value
if (y1 < y2)
{
ymin = y1;
ymax = y2;
}
else
{
ymin = y2;
ymax = y1;
}
// draw line in terms of x slope
float slope = xdiff / ydiff;
for (float y = ymin; y <= ymax; y += 1.0f)
{
float x = x1 + ((y - y1) * slope);
setPixel(x, y,color);
}
}}
else
;
}
void drawLine(x_yCoordinate c1,x_yCoordinate c2,Color color)
{
drawLine(c1.x,c1.y,c2.x,c2.y,color);
}
void drawPolygon(x_yCoordinate c1, x_yCoordinate c2, x_yCoordinate c3, Color color)
{
drawLine(c1,c2,color);
drawLine(c2,c3,color);
drawLine(c3,c1,color);
}
void drawPolygon(x_yCoordinate c1, x_yCoordinate c2,
x_yCoordinate c3,x_yCoordinate c4, Color color)
{
drawLine(c1,c2,color);
drawLine(c2,c3,color);
drawLine(c3,c4,color);
drawLine(c4,c1,color);
}
Edge::Edge(x_yCoordinate c1,const Color &color1,x_yCoordinate c2,const Color &color2){
if (c1.y < c2.y) {
Color1 = color1;
X1 = c1.x;
Y1 = c1.y;
Z1 = c1.z;
Color2 = color2;
X2 = c2.x;
Y2 = c2.y;
Z2 = c2.z;
} else {
Color1 = color2;
X1 = c2.x;
Y1 = c2.y;
Z1 = c2.z;
Color2 = color1;
X2 = c1.x;
Y2 = c1.y;
Z2 = c1.z;
}
}
Span::Span( int x1,const Color &color1, int x2,const Color &color2) {
if (x1 < x2) {
Color1 = color1;
X1 = x1;
Color2 = color2;
X2 = x2;
} else {
Color1 = color2;
X1 = x2;
Color2 = color1;
X2 = x1;
}
}
void Rasterizer::DrawSpan(const Span &span, int y) {
int xdiff = span.X2 - span.X1;
if (xdiff == 0)
return;
Color colordiff = span.Color2 - span.Color1;
float factor = 0.0f;
float factorStep = 1.0f / (float) xdiff;
// draw each pixel in the span
for (int x = span.X1; x < span.X2; x++) {
depth = (-D-A*x-B*y)/C;
if((x<=WINDOW_X/2 && x>=-WINDOW_X/2) && (y<=WINDOW_Y/2 && y>=-WINDOW_Y/2))
{
if(depth < z[x+600][y+350]){
z[x+600][y+350]=depth;
setPixel(x, y,span.Color1 + (colordiff * factor));
}
else
;
factor += factorStep;
}
}
}
void Rasterizer::clearZbuffer(){
for(int i=0;i<1200;i++)
{
for(int j=0;j<700;j++)
{
z[i][j]=99999999;
}
}
}
void Rasterizer::DrawSpansBetweenEdges(const Edge &e1, const Edge &e2) {
// calculate difference between the y coordinates
// of the first edge and return if 0
float e1ydiff = (float) (e1.Y2 - e1.Y1);
if (e1ydiff == 0.0f)
return;
// calculate difference between the y coordinates
// of the second edge and return if 0
float e2ydiff = (float) (e2.Y2 - e2.Y1);
if (e2ydiff == 0.0f)
return;
// calculate differences between the x coordinates
// and colors of the points of the edges
float e1xdiff = (float) (e1.X2 - e1.X1);
float e2xdiff = (float) (e2.X2 - e2.X1);
Color e1colordiff = (e1.Color2 - e1.Color1);
Color e2colordiff = (e2.Color2 - e2.Color1);
// calculate factors to use for interpolation
// with the edges and the step values to increase
// them by after drawing each span
float factor1 = (float) (e2.Y1 - e1.Y1) / e1ydiff;
float factorStep1 = 1.0f / e1ydiff;
float factor2 = 0.0f;
float factorStep2 = 1.0f / e2ydiff;
// loop through the lines between the edges and draw spans
for (int y = e2.Y1; y < e2.Y2; y++) {
// create and draw span
Span span(e1.X1 + (int) (e1xdiff * factor1),e1.Color1 + (e1colordiff * factor1),
e2.X1 + (int) (e2xdiff * factor2),e2.Color1 + (e2colordiff * factor2));
DrawSpan(span, y);
// increase factors
factor1 += factorStep1;
factor2 += factorStep2;
}
}
void Rasterizer::DrawTriangle(x_yCoordinate c1,const Color &color1,x_yCoordinate c2,const Color &color2
,x_yCoordinate c3,const Color &color3) {
x_yCoordinate V1 = c2-c1;
x_yCoordinate V2 = c3-c2;
x_yCoordinate ABC = V1.crossProduct(V2);
//x_yCoordinate PP(0,0,1);
//n=ABC.getUnitVector();
//k = PP.getUnitVector().dotProduct(n);
A = ABC.x;
B = ABC.y;
C = ABC.z;
D = -A*c1.x-B*c1.y-C*c1.z;
//k = (c1.z+c2.z+c3.z)/3;
// create edges for the triangle
Edge edges[3] = { Edge(c1,color1,c2,color2), Edge(c2,color2,c3,color3),Edge(c3,color3,c1,color1)};
int maxLength = 0;
int longEdge = 0;
// find edge with the greatest length in the y axis
for (int i = 0; i < 3; i++) {
int length = edges[i].Y2 - edges[i].Y1;
if (length > maxLength) {
maxLength = length;
longEdge = i;
}
}
int shortEdge1 = (longEdge + 1) % 3;
int shortEdge2 = (longEdge + 2) % 3;
// draw spans between edges; the long edge can be drawn
// with the shorter edges to draw the full triangle
DrawSpansBetweenEdges(edges[longEdge], edges[shortEdge1]);
DrawSpansBetweenEdges(edges[longEdge], edges[shortEdge2]);
}