Blitter line drawing improvements

projects/openttd_vs140.vcxproj

@@ -1201,8 +1201,8 @@
     <ClInclude Include="..\src\blitter\8bpp_optimized.hpp" />
     <ClCompile Include="..\src\blitter\8bpp_simple.cpp" />
     <ClInclude Include="..\src\blitter\8bpp_simple.hpp" />
-    <ClCompile Include="..\src\blitter\base.cpp" />
     <ClInclude Include="..\src\blitter\base.hpp" />
+    <ClInclude Include="..\src\blitter\common.hpp" />
     <ClInclude Include="..\src\blitter\factory.hpp" />
     <ClCompile Include="..\src\blitter\null.cpp" />
     <ClInclude Include="..\src\blitter\null.hpp" />

projects/openttd_vs140.vcxproj.filters

@@ -2691,12 +2691,12 @@
     <ClInclude Include="..\src\blitter\8bpp_simple.hpp">
       <Filter>Blitters</Filter>
     </ClInclude>
-    <ClCompile Include="..\src\blitter\base.cpp">
-      <Filter>Blitters</Filter>
-    </ClCompile>
     <ClInclude Include="..\src\blitter\base.hpp">
       <Filter>Blitters</Filter>
     </ClInclude>
+    <ClInclude Include="..\src\blitter\common.hpp">
+      <Filter>Blitters</Filter>
+    </ClInclude>
     <ClInclude Include="..\src\blitter\factory.hpp">
       <Filter>Blitters</Filter>
     </ClInclude>

projects/openttd_vs141.vcxproj

@@ -1201,8 +1201,8 @@
     <ClInclude Include="..\src\blitter\8bpp_optimized.hpp" />
     <ClCompile Include="..\src\blitter\8bpp_simple.cpp" />
     <ClInclude Include="..\src\blitter\8bpp_simple.hpp" />
-    <ClCompile Include="..\src\blitter\base.cpp" />
     <ClInclude Include="..\src\blitter\base.hpp" />
+    <ClInclude Include="..\src\blitter\common.hpp" />
     <ClInclude Include="..\src\blitter\factory.hpp" />
     <ClCompile Include="..\src\blitter\null.cpp" />
     <ClInclude Include="..\src\blitter\null.hpp" />

projects/openttd_vs141.vcxproj.filters

@@ -2691,12 +2691,12 @@
     <ClInclude Include="..\src\blitter\8bpp_simple.hpp">
       <Filter>Blitters</Filter>
     </ClInclude>
-    <ClCompile Include="..\src\blitter\base.cpp">
-      <Filter>Blitters</Filter>
-    </ClCompile>
     <ClInclude Include="..\src\blitter\base.hpp">
       <Filter>Blitters</Filter>
     </ClInclude>
+    <ClInclude Include="..\src\blitter\common.hpp">
+      <Filter>Blitters</Filter>
+    </ClInclude>
     <ClInclude Include="..\src\blitter\factory.hpp">
       <Filter>Blitters</Filter>
     </ClInclude>

source.list

@@ -948,8 +948,8 @@ blitter/8bpp_optimized.hpp
 blitter/8bpp_simple.cpp
 blitter/8bpp_simple.hpp
 #end
-blitter/base.cpp
 blitter/base.hpp
+blitter/common.hpp
 blitter/factory.hpp
 blitter/null.cpp
 blitter/null.hpp

src/blitter/32bpp_anim.cpp

@@ -12,6 +12,7 @@
 #include "../stdafx.h"
 #include "../video/video_driver.hpp"
 #include "32bpp_anim.hpp"
+#include "common.hpp"
 
 #include "../table/sprites.h"
 
@@ -321,6 +322,24 @@ void Blitter_32bppAnim::SetPixel(void *video, int x, int y, uint8 colour)
 	this->anim_buf[this->ScreenToAnimOffset((uint32 *)video) + x + y * this->anim_buf_pitch] = colour | (DEFAULT_BRIGHTNESS << 8);
 }
 
+void Blitter_32bppAnim::DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash)
+{
+	const Colour c = LookupColourInPalette(colour);
+
+	if (_screen_disable_anim)  {
+		this->DrawLineGeneric(x, y, x2, y2, screen_width, screen_height, width, dash, [&](int x, int y) {
+			*((Colour *)video + x + y * _screen.pitch) = c;
+		});
+	} else {
+		uint16 * const offset_anim_buf = this->anim_buf + this->ScreenToAnimOffset((uint32 *)video);
+		const uint16 anim_colour = colour | (DEFAULT_BRIGHTNESS << 8);
+		this->DrawLineGeneric(x, y, x2, y2, screen_width, screen_height, width, dash, [&](int x, int y) {
+			*((Colour *)video + x + y * _screen.pitch) = c;
+			offset_anim_buf[x + y * this->anim_buf_pitch] = anim_colour;
+		});
+	}
+}
+
 void Blitter_32bppAnim::DrawRect(void *video, int width, int height, uint8 colour)
 {
 	if (_screen_disable_anim) {

src/blitter/32bpp_anim.hpp

@@ -40,6 +40,7 @@ class Blitter_32bppAnim : public Blitter_32bppOptimized {
 	/* virtual */ void Draw(Blitter::BlitterParams *bp, BlitterMode mode, ZoomLevel zoom);
 	/* virtual */ void DrawColourMappingRect(void *dst, int width, int height, PaletteID pal);
 	/* virtual */ void SetPixel(void *video, int x, int y, uint8 colour);
+	/* virtual */ void DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash);
 	/* virtual */ void DrawRect(void *video, int width, int height, uint8 colour);
 	/* virtual */ void CopyFromBuffer(void *video, const void *src, int width, int height);
 	/* virtual */ void CopyToBuffer(const void *video, void *dst, int width, int height);

src/blitter/32bpp_base.cpp

@@ -11,6 +11,7 @@
 
 #include "../stdafx.h"
 #include "32bpp_base.hpp"
+#include "common.hpp"
 
 #include "../safeguards.h"
 
@@ -24,6 +25,14 @@ void Blitter_32bppBase::SetPixel(void *video, int x, int y, uint8 colour)
 	*((Colour *)video + x + y * _screen.pitch) = LookupColourInPalette(colour);
 }
 
+void Blitter_32bppBase::DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash)
+{
+	const Colour c = LookupColourInPalette(colour);
+	this->DrawLineGeneric(x, y, x2, y2, screen_width, screen_height, width, dash, [=](int x, int y) {
+		*((Colour *)video + x + y * _screen.pitch) = c;
+	});
+}
+
 void Blitter_32bppBase::DrawRect(void *video, int width, int height, uint8 colour)
 {
 	Colour colour32 = LookupColourInPalette(colour);

src/blitter/32bpp_base.hpp

@@ -23,6 +23,7 @@ class Blitter_32bppBase : public Blitter {
 	/* virtual */ uint8 GetScreenDepth() { return 32; }
 	/* virtual */ void *MoveTo(void *video, int x, int y);
 	/* virtual */ void SetPixel(void *video, int x, int y, uint8 colour);
+	/* virtual */ void DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash);
 	/* virtual */ void DrawRect(void *video, int width, int height, uint8 colour);
 	/* virtual */ void CopyFromBuffer(void *video, const void *src, int width, int height);
 	/* virtual */ void CopyToBuffer(const void *video, void *dst, int width, int height);

src/blitter/8bpp_base.cpp

@@ -12,6 +12,7 @@
 #include "../stdafx.h"
 #include "../gfx_func.h"
 #include "8bpp_base.hpp"
+#include "common.hpp"
 
 #include "../safeguards.h"
 
@@ -35,6 +36,13 @@ void Blitter_8bppBase::SetPixel(void *video, int x, int y, uint8 colour)
 	*((uint8 *)video + x + y * _screen.pitch) = colour;
 }
 
+void Blitter_8bppBase::DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash)
+{
+	this->DrawLineGeneric(x, y, x2, y2, screen_width, screen_height, width, dash, [=](int x, int y) {
+		*((uint8 *)video + x + y * _screen.pitch) = colour;
+	});
+}
+
 void Blitter_8bppBase::DrawRect(void *video, int width, int height, uint8 colour)
 {
 	do {

src/blitter/8bpp_base.hpp

@@ -21,6 +21,7 @@ class Blitter_8bppBase : public Blitter {
 	/* virtual */ void DrawColourMappingRect(void *dst, int width, int height, PaletteID pal);
 	/* virtual */ void *MoveTo(void *video, int x, int y);
 	/* virtual */ void SetPixel(void *video, int x, int y, uint8 colour);
+	/* virtual */ void DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash);
 	/* virtual */ void DrawRect(void *video, int width, int height, uint8 colour);
 	/* virtual */ void CopyFromBuffer(void *video, const void *src, int width, int height);
 	/* virtual */ void CopyToBuffer(const void *video, void *dst, int width, int height);

src/blitter/base.hpp

@@ -122,7 +122,7 @@ class Blitter {
 	 * @param width Line width.
 	 * @param dash Length of dashes for dashed lines. 0 means solid line.
 	 */
-	virtual void DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash = 0);
+	virtual void DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash = 0) = 0;
 
 	/**
 	 * Copy from a buffer to the screen.
@@ -203,6 +203,8 @@ class Blitter {
 	virtual void PostResize() { };
 
 	virtual ~Blitter() { }
+
+	template <typename SetPixelT> void DrawLineGeneric(int x, int y, int x2, int y2, int screen_width, int screen_height, int width, int dash, SetPixelT set_pixel);
 };
 
 #endif /* BLITTER_BASE_HPP */

src/blitter/base.cpp → src/blitter/common.hpp

@@ -7,15 +7,18 @@
  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
  */
 
-/** @file base.cpp Implementation of the base for all blitters. */
+/** @file common.hpp Common functionality for all blitter implementations. */
+
+#ifndef BLITTER_COMMON_HPP
+#define BLITTER_COMMON_HPP
 
-#include "../stdafx.h"
 #include "base.hpp"
 #include "../core/math_func.hpp"
 
-#include "../safeguards.h"
+#include <utility>
 
-void Blitter::DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash)
+template <typename SetPixelT>
+void Blitter::DrawLineGeneric(int x, int y, int x2, int y2, int screen_width, int screen_height, int width, int dash, SetPixelT set_pixel)
 {
 	int dy;
 	int dx;
@@ -40,7 +43,7 @@ void Blitter::DrawLine(void *video, int x, int y, int x2, int y2, int screen_wid
 
 	if (dx == 0 && dy == 0) {
 		/* The algorithm below cannot handle this special case; make it work at least for line width 1 */
-		if (x >= 0 && x < screen_width && y >= 0 && y < screen_height) this->SetPixel(video, x, y, colour);
+		if (x >= 0 && x < screen_width && y >= 0 && y < screen_height) set_pixel(x, y);
 		return;
 	}
 
@@ -49,11 +52,11 @@ void Blitter::DrawLine(void *video, int x, int y, int x2, int y2, int screen_wid
 		/* compute frac_diff = width * sqrt(dx*dx + dy*dy)
 		 * Start interval:
 		 *    max(dx, dy) <= sqrt(dx*dx + dy*dy) <= sqrt(2) * max(dx, dy) <= 3/2 * max(dx, dy) */
-		int frac_sq = width * width * (dx * dx + dy * dy);
+		int64 frac_sq = ((int64) width) * ((int64) width) * (((int64) dx) * ((int64) dx) + ((int64) dy) * ((int64) dy));
 		int frac_max = 3 * frac_diff / 2;
 		while (frac_diff < frac_max) {
 			int frac_test = (frac_diff + frac_max) / 2;
-			if (frac_test * frac_test < frac_sq) {
+			if (((int64) frac_test) * ((int64) frac_test) < frac_sq) {
 				frac_diff = frac_test + 1;
 			} else {
 				frac_max = frac_test - 1;
@@ -65,25 +68,52 @@ void Blitter::DrawLine(void *video, int x, int y, int x2, int y2, int screen_wid
 	if (dash == 0) dash = 1;
 	int dash_count = 0;
 	if (dx > dy) {
+		if (stepx < 0) {
+			std::swap(x, x2);
+			std::swap(y, y2);
+			stepy = -stepy;
+		}
+		if (x2 < 0 || x >= screen_width) return;
+
 		int y_low     = y;
 		int y_high    = y;
 		int frac_low  = dy - frac_diff / 2;
 		int frac_high = dy + frac_diff / 2;
 
-		while (frac_low + dx / 2 < 0) {
+		while (frac_low < -(dx / 2)) {
 			frac_low += dx;
 			y_low -= stepy;
 		}
-		while (frac_high - dx / 2 >= 0) {
+		while (frac_high >= dx / 2) {
 			frac_high -= dx;
 			y_high += stepy;
 		}
-		x2 += stepx;
+
+		if (x < 0) {
+			dash_count = (-x) % (dash + gap);
+			auto adjust_frac = [&](int64 frac, int &y_bound) -> int {
+				frac -= ((int64) dy) * ((int64) x);
+				if (frac >= 0) {
+					int quotient = frac / dx;
+					int remainder = frac % dx;
+					y_bound += (1 + quotient) * stepy;
+					frac = remainder - dx;
+				}
+				return frac;
+			};
+			frac_low = adjust_frac(frac_low, y_low);
+			frac_high = adjust_frac(frac_high, y_high);
+			x = 0;
+		}
+		x2++;
+		if (x2 > screen_width) {
+			x2 = screen_width;
+		}
 
 		while (x != x2) {
-			if (dash_count < dash && x >= 0 && x < screen_width) {
+			if (dash_count < dash) {
 				for (int y = y_low; y != y_high; y += stepy) {
-					if (y >= 0 && y < screen_height) this->SetPixel(video, x, y, colour);
+					if (y >= 0 && y < screen_height) set_pixel(x, y);
 				}
 			}
 			if (frac_low >= 0) {
@@ -94,31 +124,58 @@ void Blitter::DrawLine(void *video, int x, int y, int x2, int y2, int screen_wid
 				y_high += stepy;
 				frac_high -= dx;
 			}
-			x += stepx;
+			x++;
 			frac_low += dy;
 			frac_high += dy;
 			if (++dash_count >= dash + gap) dash_count = 0;
 		}
 	} else {
+		if (stepy < 0) {
+			std::swap(x, x2);
+			std::swap(y, y2);
+			stepx = -stepx;
+		}
+		if (y2 < 0 || y >= screen_height) return;
+
 		int x_low     = x;
 		int x_high    = x;
 		int frac_low  = dx - frac_diff / 2;
 		int frac_high = dx + frac_diff / 2;
 
-		while (frac_low + dy / 2 < 0) {
+		while (frac_low < -(dy / 2)) {
 			frac_low += dy;
 			x_low -= stepx;
 		}
-		while (frac_high - dy / 2 >= 0) {
+		while (frac_high >= dy / 2) {
 			frac_high -= dy;
 			x_high += stepx;
 		}
-		y2 += stepy;
+
+		if (y < 0) {
+			dash_count = (-y) % (dash + gap);
+			auto adjust_frac = [&](int64 frac, int &x_bound) -> int {
+				frac -= ((int64) dx) * ((int64) y);
+				if (frac >= 0) {
+					int quotient = frac / dy;
+					int remainder = frac % dy;
+					x_bound += (1 + quotient) * stepx;
+					frac = remainder - dy;
+				}
+				return frac;
+			};
+			frac_low = adjust_frac(frac_low, x_low);
+			frac_high = adjust_frac(frac_high, x_high);
+			y = 0;
+		}
+		y2++;
+		if (y2 > screen_height) {
+			y2 = screen_height;
+		}
 
 		while (y != y2) {
-			if (dash_count < dash && y >= 0 && y < screen_height) {
+			if (dash_count < dash) {
 				for (int x = x_low; x != x_high; x += stepx) {
-					if (x >= 0 && x < screen_width) this->SetPixel(video, x, y, colour);
+					if (x >= 0 && x < screen_width) set_pixel(x, y);
 				}
 			}
 			if (frac_low >= 0) {
@@ -129,10 +186,12 @@ void Blitter::DrawLine(void *video, int x, int y, int x2, int y2, int screen_wid
 				x_high += stepx;
 				frac_high -= dy;
 			}
-			y += stepy;
+			y++;
 			frac_low += dx;
 			frac_high += dx;
 			if (++dash_count >= dash + gap) dash_count = 0;
 		}
 	}
 }
+
+#endif /* BLITTER_COMMON_HPP */