I'm currently programming a 3D software renderer where I am rasterizing triangles based on a function to take x and y coordinates to draw 3 lines to draw a triangle that works just fine. However, my code to interpolate through the triangle to fill it with the color of a BufferedImage is very costly and eats at the performance of my application. I was informed that instantiating a new Color object and using the drawLine() method to draw a pixel to the screen is very costly on the CPU. Is there any alternative to this drawing routine such as holding all possible RGB's/pixels on the screen in an array and calling from that to draw to the screen to limit the number of pixels drawn?
public static void drawTriangle(Graphics2D g2, double x1, double y1, double x2, double y2, double x3, double y3)
{
g2.setStroke(new BasicStroke(2));
g2.draw(new Line2D.Double(x1, y1, x2, y2));
g2.draw(new Line2D.Double(x2, y2, x3, y3));
g2.draw(new Line2D.Double(x3, y3, x1, y1));
}
public static void texturedTriangle(Graphics2D g2, int x1, int y1, double u1, double v1, int x2, int y2, double
u2, double v2, int x3, int y3, double u3, double v3, BufferedImage img, double visibility, boolean fog)
{
if(y2 < y1)
{
int temp = y1;
y1 = y2;
y2 = temp;
int tempx = x1;
x1 = x2;
x2 = tempx;
double tempu = u1;
u1 = u2;
u2 = tempu;
double tempv = v1;
v1 = v2;
v2 = tempv;
}
if(y3 < y1)
{
int temp = y1;
y1 = y3;
y3 = temp;
int tempx = x1;
x1 = x3;
x3 = tempx;
double tempu = u1;
u1 = u3;
u3 = tempu;
double tempv = v1;
v1 = v3;
v3 = tempv;
}
if(y3 < y2)
{
int temp = y2;
y2 = y3;
y3 = temp;
int tempx = x2;
x2 = x3;
x3 = tempx;
double tempu = u2;
u2 = u3;
u3 = tempu;
double tempv = v2;
v2 = v3;
v3 = tempv;
}
int dy1 = y2 - y1;
int dx1 = x2 - x1;
double dv1 = v2 - v1;
double du1 = u2 - u1;
int dy2 = y3 - y1;
int dx2 = x3 - x1;
double dv2 = v3 - v1;
double du2 = u3 - u1;
double tex_u, tex_v;
double dax_step = 0, dbx_step = 0, du1_step = 0, dv1_step = 0, du2_step = 0, dv2_step = 0;
if (dy1 != 0) dax_step = dx1 / (float)Math.abs(dy1);
if (dy2 != 0) dbx_step = dx2 / (float)Math.abs(dy2);
if (dy1 != 0) du1_step = du1 / (float)Math.abs(dy1);
if (dy1 != 0) dv1_step = dv1 / (float)Math.abs(dy1);
if (dy2 != 0) du2_step = du2 / (float)Math.abs(dy2);
if (dy2 != 0) dv2_step = dv2 / (float)Math.abs(dy2);
if(dy1 != 0)
{
for(int i = y1; i <= y2; i++)
{
int ax = (int)(x1 + (i - y1) * dax_step);
int bx = (int)(x1 + (i - y1) * dbx_step);
double tex_su = u1 + (float)(i - y1) * du1_step;
double tex_sv = v1 + (float)(i - y1) * dv1_step;
double tex_eu = u1 + (float)(i - y1) * du2_step;
double tex_ev = v1 + (float)(i - y1) * dv2_step;
if(ax > bx)
{
int temp = ax;
ax = bx;
bx = temp;
double temps = tex_su;
tex_su = tex_eu;
tex_eu = temps;
double tempv = tex_sv;
tex_sv = tex_ev;
tex_ev = tempv;
}
tex_u = tex_su;
tex_v = tex_sv;
double tstep = 1.0 / (float)(bx-ax);
double t = 0.0;
for(int j = ax; j < bx; j++)
{
tex_u = (1.0 - t) * tex_su + t * tex_eu;
tex_v = (1.0 - t) * tex_sv + t * tex_ev;
Color background = Color.black;
Color col = new Color(img.getRGB(
(int)Math.max(0,tex_u*(img.getWidth()-1)),
(int)Math.max(0,tex_v*(img.getHeight()-1))
));
col = blend(background, col,(float)visibility);
if(fog)
{
g2.setColor(col);
}
else
{
g2.setColor(new Color(img.getRGB(
(int)Math.max(0,tex_u*(img.getWidth()-1)),
(int)Math.max(0,tex_v*(img.getHeight()-1))
)));
}
g2.drawLine(j, i, j+1, i+1);
t += tstep;
}
}
}
dy1 = y3 - y2;
dx1 = x3 - x2;
dv1 = v3 - v2;
du1 = u3 - u2;
if (dy1 != 0) dax_step = dx1 / (float)Math.abs(dy1);
if (dy2 != 0) dbx_step = dx2 / (float)Math.abs(dy2);
du1_step = 0; dv1_step = 0;
if (dy1 != 0) du1_step = du1 /(float)Math.abs(dy1);
if (dy1 != 0) dv1_step = dv1 / (float)Math.abs(dy1);
if(dy1 != 0)
{
for(int i = y2; i <= y3; i++)
{
int ax = (int)(x2 + (float)(i - y2) * dax_step);
int bx = (int)(x1 + (float)(i - y1) * dbx_step);
double tex_su = u2 + (float)(i - y2) * du1_step;
double tex_sv = v2 + (float)(i - y2) * dv1_step;
double tex_eu = u1 + (float)(i - y1) * du2_step;
double tex_ev = v1 + (float)(i - y1) * dv2_step;
if(ax > bx)
{
int temp = ax;
ax = bx;
bx = temp;
double temps = tex_su;
tex_su = tex_eu;
tex_eu = temps;
double tempv = tex_sv;
tex_sv = tex_ev;
tex_ev = tempv;
}
tex_u = tex_su;
tex_v = tex_sv;
double tstep = 1.0/ (float)(bx-ax);
double t = 0.0;
for(int j = ax; j < bx; j++)
{
tex_u = (1.0 - t) * tex_su + t * tex_eu;
tex_v = (1.0 - t) * tex_sv + t * tex_ev;
Color background = Color.black;
Color col = new Color(img.getRGB(
(int)Math.max(0,tex_u*(img.getWidth()-1)),
(int)Math.max(0,tex_v*(img.getHeight()-1))
));
col = blend(background, col,(float)visibility);
if(fog)
{
g2.setColor(col);
}
else
{
g2.setColor(new Color(img.getRGB(
(int)Math.max(0,tex_u*(img.getWidth()-1)),
(int)Math.max(0,tex_v*(img.getHeight()-1))
)));
}
g2.drawLine(j, i, j+1, i+1);
t += tstep;
}
}
}
}
public static Color blend( Color c1, Color c2, float ratio )
{
if ( ratio > 1f ) ratio = 1f;
else if ( ratio < 0f ) ratio = 0f;
float iRatio = 1.0f - ratio;
int i1 = c1.getRGB();
int i2 = c2.getRGB();
int a1 = (i1 >> 24 & 0xff);
int r1 = ((i1 & 0xff0000) >> 16);
int g1 = ((i1 & 0xff00) >> 8);
int b1 = (i1 & 0xff);
int a2 = (i2 >> 24 & 0xff);
int r2 = ((i2 & 0xff0000) >> 16);
int g2 = ((i2 & 0xff00) >> 8);
int b2 = (i2 & 0xff);
int a = (int)((a1 * iRatio) + (a2 * ratio));
int r = (int)((r1 * iRatio) + (r2 * ratio));
int g = (int)((g1 * iRatio) + (g2 * ratio));
int b = (int)((b1 * iRatio) + (b2 * ratio));
return new Color( a << 24 | r << 16 | g << 8 | b );
}
}
