[Scummvm-git-logs] scummvm master -> 9e8809a2f3e8f7cd5b2aaef84a7b8d161aa777c2

[antoniou79]

This automated email contains information about 1 new commit which have been
pushed to the 'scummvm' repo located at https://github.com/scummvm/scummvm .

Summary:
9e8809a2f3 BLADERUNNER: pre-calculate some math constants


Commit: 9e8809a2f3e8f7cd5b2aaef84a7b8d161aa777c2
    https://github.com/scummvm/scummvm/commit/9e8809a2f3e8f7cd5b2aaef84a7b8d161aa777c2
Author: Carlo Bramini (30959007+carlo-bramini at users.noreply.github.com)
Date: 2023-01-12T15:51:02+02:00

Commit Message:
BLADERUNNER: pre-calculate some math constants

There are some values that are read from stream and never changed by the calculations. Since they are used as parameter on expensive math functions like cos() and tan(), it would be worth to pre-calculate their values and use them when needed.

Changed paths:
    engines/bladerunner/fog.cpp
    engines/bladerunner/fog.h


diff --git a/engines/bladerunner/fog.cpp b/engines/bladerunner/fog.cpp
index 5d185b513ba..177f912c87e 100644
--- a/engines/bladerunner/fog.cpp
+++ b/engines/bladerunner/fog.cpp
@@ -115,7 +115,8 @@ void Fog::setupFrame(int frame) {
 void FogSphere::read(Common::ReadStream *stream, int frameCount) {
 	_frameCount = frameCount;
 	int size = readCommon(stream);
-	_radius = stream->readFloatLE();
+	float radius = stream->readFloatLE();
+	_radius_sq = radius * radius;
 	readAnimationData(stream, size - 52);
 }
 
@@ -135,12 +136,14 @@ void FogSphere::calculateCoeficient(Vector3 position, Vector3 viewPosition, floa
 	Vector3 rayDirection = (rayDestination - rayOrigin).normalize();
 
 	float b = Vector3::dot(rayDirection, rayOrigin);
-	float c = Vector3::dot(rayOrigin, rayOrigin) - (_radius * _radius);
+	float c = Vector3::dot(rayOrigin, rayOrigin) - _radius_sq;
 	float d = b * b - c;
 
 	if (d >= 0.0f) { // there is an interstection between ray and the sphere
-		Vector3 intersection1 = rayOrigin + (-b - sqrt(d)) * rayDirection;
-		Vector3 intersection2 = rayOrigin + (-b + sqrt(d)) * rayDirection;
+		float sqrt_d = sqrt(d);
+
+		Vector3 intersection1 = rayOrigin + (-b - sqrt_d) * rayDirection;
+		Vector3 intersection2 = rayOrigin + (-b + sqrt_d) * rayDirection;
 
 		Vector3 intersection1World = _inverted * intersection1;
 		Vector3 intersection2World = _inverted * intersection2;
@@ -165,7 +168,12 @@ void FogSphere::calculateCoeficient(Vector3 position, Vector3 viewPosition, floa
 void FogCone::read(Common::ReadStream *stream, int frameCount) {
 	_frameCount = frameCount;
 	int size = readCommon(stream);
-	_coneAngle = stream->readFloatLE();
+	float coneAngle = stream->readFloatLE();
+	float tan_coneAngle = tan(coneAngle);
+
+	_cos_coneAngle = cos(coneAngle);
+	_tan_coneAngle_sq = tan_coneAngle * tan_coneAngle;
+
 	readAnimationData(stream, size - 52);
 }
 
@@ -190,14 +198,14 @@ void FogCone::calculateCoeficient(Vector3 position, Vector3 viewPosition, float
 
 		float cosTheta = sqrt(1.0f - Vector3::dot(planeNormal, v) * Vector3::dot(planeNormal, v));
 
-		if (cosTheta > cos(_coneAngle)) {
+		if (cosTheta > _cos_coneAngle) {
 			Vector3 u = Vector3::cross(v, planeNormal).normalize();
 			Vector3 w = Vector3::cross(u, v).normalize();
 
 			float tanTheta = sqrt(1.0f - cosTheta * cosTheta) / cosTheta;
 
 			Vector3 temp1 = tanTheta * w;
-			Vector3 temp2 = sqrt(tan(_coneAngle) * tan(_coneAngle) - tanTheta * tanTheta) * u;
+			Vector3 temp2 = sqrt(_tan_coneAngle_sq - tanTheta * tanTheta) * u;
 
 			Vector3 delta1 = v + temp1 - temp2;
 			Vector3 delta2 = v + temp1 + temp2;
diff --git a/engines/bladerunner/fog.h b/engines/bladerunner/fog.h
index 8f45b6b9574..b94f37b4c82 100644
--- a/engines/bladerunner/fog.h
+++ b/engines/bladerunner/fog.h
@@ -80,10 +80,10 @@ protected:
 
 class FogSphere : public Fog {
 private:
-	float _radius;
+	float _radius_sq;
 
 public:
-	FogSphere():_radius(0.0f) {};
+	FogSphere():_radius_sq(0.0f) {};
 
 	void read(Common::ReadStream *stream, int frameCount) override;
 	void calculateCoeficient(Vector3 position, Vector3 viewPosition, float *coeficient) override;
@@ -91,10 +91,11 @@ public:
 
 class FogCone : public Fog {
 private:
-	float _coneAngle;
+	float _tan_coneAngle_sq;
+	float _cos_coneAngle;
 
 public:
-	FogCone():_coneAngle(0.0f) {};
+	FogCone():_tan_coneAngle_sq(0.0f), _cos_coneAngle(1.0f) {};
 
 	void read(Common::ReadStream *stream, int frameCount) override;
 	void calculateCoeficient(Vector3 position, Vector3 viewPosition, float *coeficient) override;