Change field of view according to speed

include/rasterizer.h

@@ -46,6 +46,8 @@ namespace Rasterizer {
 	void reset();
 	extern fp *depthBuffer;
 
+	void setFOV(int fov);
+
 	vec3d toDevice(vec3d p);
 	vec3i toScreen(vec3d p);
 	void drawLine(vec3d p0, vec3d p1);

include/rmath.h

@@ -25,6 +25,8 @@ fp _fp_sin(fp x);
 
 fp fp_sin(fp x);
 fp fp_cos(fp x);
+fp fp_tan(fp x);
+fp fp_atan(fp x);
 fp fp_atan2(fp y, fp x);
 
 float isqrt(float x);

src/main.cpp

@@ -1121,6 +1121,7 @@ int main(){
 	Model carModel = Model(carMesh);
 
 	Rasterizer::init();
+	Rasterizer::setFOV(70);
 	while(true){
 		Rasterizer::reset();
 
@@ -1151,6 +1152,8 @@ int main(){
 		if(wheelSpeed < 0)
 			wheelSpeed = 0;
 
+		Rasterizer::setFOV(70 + 100.0f / carSpeed.i_length());
+
 		carSpeed.x = carSpeed.x + wheelSpeed * float(fp_cos(fp(carAngle))) * Time::delta / 150.0f;
 		carSpeed.z = carSpeed.z + wheelSpeed * float(fp_sin(fp(0)-fp(carAngle))) * Time::delta / 150.0f;
 		carSpeed.x = carSpeed.x - (carSpeed.x * 0.01f) * Time::delta;

src/rasterizer.cpp

@@ -33,6 +33,8 @@ namespace Rasterizer {
 
 	fp *depthBuffer;
 
+	fp fov_d = 1;
+
 	void init(){
 		clippingPlanes[0] = {{0, 0, 1}, fp(0)-fp(NEAR_PLANE)}; // near
 		clippingPlanes[1] = {{fp(I_SQRT_2), 0, fp(I_SQRT_2)}, 0}; // left
@@ -47,10 +49,29 @@ namespace Rasterizer {
 		}
 	}
 
+	void setFOV(int fov){
+		fp half_fov_rad = fp(fov) * fp(PI) / fp(180) / fp(2);
+		fov_d = fp_tan(half_fov_rad) * fp(2);
+
+		half_fov_rad = half_fov_rad + fp(0.1);
+		fp a = fp_cos(half_fov_rad - fp(HALF_PI));
+		fp b = fp_sin(half_fov_rad - fp(HALF_PI));
+
+		half_fov_rad = fp_atan(fp_tan(half_fov_rad) * (fp(RENDER_HEIGHT)/fp(RENDER_WIDTH)));
+		fp c = fp_cos(half_fov_rad - fp(HALF_PI));
+		fp d = fp_sin(half_fov_rad - fp(HALF_PI));
+
+		clippingPlanes[0] = {{0, 0, 1}, fp(0)-fp(NEAR_PLANE)}; // near
+		clippingPlanes[1] = {{b, 0, a}, 0}; // left
+		clippingPlanes[2] = {{fp(0)-b, 0, a}, 0}; // right
+		clippingPlanes[3] = {{0, d, c}, 0}; // bottom
+		clippingPlanes[4] = {{0, fp(0)-d, c}, 0}; // top
+	}
+
 	inline vec3d toDevice(vec3d p){
 		return {
-			p.x / p.z,
-			p.y / p.z,
+			p.x / p.z / fov_d,
+			p.y / p.z / fov_d,
 			p.z
 		};
 	}

src/rmath.cpp

@@ -68,8 +68,18 @@ fp fp_cos(fp x){
 	return fp_sin(x+fp(HALF_PI));
 }
 
+fp fp_tan(fp x){
+	return fp_sin(x) / fp_cos(x);
+}
+
+fp _fp_atan(fp x){
+	return fp(PI)/fp(4) * x - x * (fp_abs(x) - fp(1)) * (fp(0.245) + fp(0.066) * fp_abs(x));
+}
 fp fp_atan(fp x){
-	return fp(PI)*fp(4) * x - x * (fp_abs(x) - fp(1)) * (fp(0.245) + fp(0.066) * fp_abs(x));
+	if(x < 1)
+		return _fp_atan(x);
+	else
+		return fp(HALF_PI) - _fp_atan(fp(1)/x);
 }
 fp fp_atan2(fp y, fp x){
 	if(x == 0 || y == 0)