From 5c9d223e3203317ec6edb1b367f90e29415fb13c Mon Sep 17 00:00:00 2001
From: "Unknown W. Brackets" <checkins@unknownbrackets.org>
Date: Sun, 14 May 2017 15:22:34 -0700
Subject: [PATCH] SoftGPU: Implement simple mipmapping for lines.

Mostly so the min/mag filter is correct.
---
 GPU/Software/Rasterizer.cpp | 66 ++++++++++++++++++++++---------------
 1 file changed, 40 insertions(+), 26 deletions(-)

diff --git a/GPU/Software/Rasterizer.cpp b/GPU/Software/Rasterizer.cpp
index 20b63d4775..0f638663c5 100644
--- a/GPU/Software/Rasterizer.cpp
+++ b/GPU/Software/Rasterizer.cpp
@@ -1198,12 +1198,9 @@ static int TexLog2(float delta) {
 	return useful - 127 * 256;
 }
 
-static inline void ApplyTexturing(Vec4<int> *prim_color, const Vec4<float> &s, const Vec4<float> &t, int maxTexLevel, u8 *texptr[], int texbufwidthbytes[]) {
-	int width = gstate.getTextureWidth(0);
-	int height = gstate.getTextureHeight(0);
-
-	float ds = s[1] - s[0];
-	float dt = t[2] - t[0];
+static inline void CalculateSamplingParams(const float ds, const float dt, const int maxTexLevel, int &level, int &levelFrac, int &filt) {
+	const int width = gstate.getTextureWidth(0);
+	const int height = gstate.getTextureHeight(0);
 
 	// With 8 bits of fraction (because texslope can be fairly precise.)
 	int detail;
@@ -1229,8 +1226,6 @@ static inline void ApplyTexturing(Vec4<int> *prim_color, const Vec4<float> &s, c
 	int mipFilt = (gstate.texfilter >> 1) & 1;
 	int magFilt = (gstate.texfilter >> 8) & 1;
 
-	int level = 0;
-	int levelFrac = 0;
 	if (detail > 0 && maxTexLevel > 0) {
 		int level8 = std::min(detail, maxTexLevel * 256);
 		if (!mipFilt) {
@@ -1239,13 +1234,31 @@ static inline void ApplyTexturing(Vec4<int> *prim_color, const Vec4<float> &s, c
 		}
 		level = level8 >> 8;
 		levelFrac = mipFilt ? level8 & 0xFF : 0;
+	} else {
+		level = 0;
+		levelFrac = 0;
 	}
-	int filt = detail > 0 ? minFilt : magFilt;
+
 	if (g_Config.iTexFiltering == 3) {
 		filt = 1;
 	} else if (g_Config.iTexFiltering == 2) {
 		filt = 0;
+	} else {
+		filt = detail > 0 ? minFilt : magFilt;
 	}
+}
+
+static inline void ApplyTexturing(Vec4<int> *prim_color, const Vec4<float> &s, const Vec4<float> &t, int maxTexLevel, u8 *texptr[], int texbufwidthbytes[]) {
+	int width = gstate.getTextureWidth(0);
+	int height = gstate.getTextureHeight(0);
+
+	float ds = s[1] - s[0];
+	float dt = t[2] - t[0];
+
+	int level;
+	int levelFrac;
+	int filt;
+	CalculateSamplingParams(ds, dt, maxTexLevel, level, levelFrac, filt);
 
 	for (int i = 0; i < 4; ++i) {
 		ApplyTexturing(prim_color[i], s[i], t[i], level, levelFrac, filt, texptr, texbufwidthbytes);
@@ -1628,21 +1641,12 @@ void DrawLine(const VertexData &v0, const VertexData &v1)
 	int maxTexLevel = gstate.getTextureMaxLevel();
 	u8 *texptr[8] = {NULL};
 
-	int magFilt = (gstate.texfilter>>8) & 1;
-	if (g_Config.iTexFiltering > 1) {
-		if (g_Config.iTexFiltering == 2) {
-			magFilt = 0;
-		} else if (g_Config.iTexFiltering == 3) {
-			magFilt = 1;
-		}
-	}
 	if ((gstate.texfilter & 4) == 0 || !g_Config.bMipMap) {
 		// No mipmapping enabled
 		maxTexLevel = 0;
 	}
 
 	if (gstate.isTextureMapEnabled() && !clearMode) {
-		// TODO: Always using level 0.
 		GETextureFormat texfmt = gstate.getTextureFormat();
 		for (int i = 0; i <= maxTexLevel; i++) {
 			u32 texaddr = gstate.getTextureAddress(i);
@@ -1668,25 +1672,35 @@ void DrawLine(const VertexData &v0, const VertexData &v1)
 				sec_color = v1.color1;
 			}
 
-			// TODO: UVGenMode?
-			Vec2<float> tc = (v0.texturecoords * (float)(steps - i) + v1.texturecoords * (float)i) / steps1;
-
 			u8 fog = 255;
 			if (gstate.isFogEnabled() && !clearMode) {
 				fog = ClampFogDepth((v0.fogdepth * (float)(steps - i) + v1.fogdepth * (float)i) / steps1);
 			}
 
-			float s = tc.s();
-			float t = tc.t();
-
 			if (gstate.isTextureMapEnabled() && !clearMode) {
+				// TODO: UVGenMode?
+				Vec2<float> tc = (v0.texturecoords * (float)(steps - i) + v1.texturecoords * (float)i) / steps1;
+				Vec2<float> tc1 = (v0.texturecoords * (float)(steps - i - 1) + v1.texturecoords * (float)(i + 1)) / steps1;
+				float s = tc.s(), s1 = tc1.s();
+				float t = tc.t(), t1 = tc1.t();
+
 				if (gstate.isModeThrough()) {
 					s *= 1.0f / (float)gstate.getTextureWidth(0);
+					s1 *= 1.0f / (float)gstate.getTextureWidth(0);
 					t *= 1.0f / (float)gstate.getTextureHeight(0);
+					t1 *= 1.0f / (float)gstate.getTextureHeight(0);
 				}
 
-				// TODO: ds/dt.
-				ApplyTexturing(prim_color, s, t, 0, 0, magFilt, texptr, texbufwidthbytes);
+				// If inc is 0, force the delta to zero.
+				float ds = xinc == 0.0f ? 0.0f : (s1 - s) * 16.0f * (1.0f / xinc);
+				float dt = yinc == 0.0f ? 0.0f : (t1 - t) * 16.0f * (1.0f / yinc);
+
+				int texLevel;
+				int texLevelFrac;
+				int texFilt;
+				CalculateSamplingParams(ds, dt, maxTexLevel, texLevel, texLevelFrac, texFilt);
+
+				ApplyTexturing(prim_color, s, t, texLevel, texLevelFrac, texFilt, texptr, texbufwidthbytes);
 			}
 
 			if (!clearMode)