[Scummvm-git-logs] scummvm master -> 68adead085f9f090b77b626df13c1a7f4cc35de3

[dreammaster]

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pushed to the 'scummvm' repo located at https://github.com/scummvm/scummvm .

Summary:
68adead085 AGS: Implement fade in/out alpha blending


Commit: 68adead085f9f090b77b626df13c1a7f4cc35de3
    https://github.com/scummvm/scummvm/commit/68adead085f9f090b77b626df13c1a7f4cc35de3
Author: Paul Gilbert (dreammaster at scummvm.org)
Date: 2021-02-14T18:08:23-08:00

Commit Message:
AGS: Implement fade in/out alpha blending

Changed paths:
    engines/ags/lib/allegro/color.cpp
    engines/ags/lib/allegro/color.h
    engines/ags/lib/allegro/gfx.cpp
    engines/ags/lib/allegro/gfx.h


diff --git a/engines/ags/lib/allegro/color.cpp b/engines/ags/lib/allegro/color.cpp
index 3c8e7af253..8da34cb41c 100644
--- a/engines/ags/lib/allegro/color.cpp
+++ b/engines/ags/lib/allegro/color.cpp
@@ -49,6 +49,7 @@ int _rgb_a_shift_32 = 0;
 
 RGB_MAP *rgb_map;
 COLOR_MAP *color_map;
+int trans_blend_alpha = -1;
 
 void color::readFromFile(AGS::Shared::Stream *file) {
 	r = file->ReadByte();
@@ -273,7 +274,7 @@ void set_blender_mode_ex(BLENDER_FUNC b15, BLENDER_FUNC b16, BLENDER_FUNC b24, B
 }
 
 void set_alpha_blender(void) {
-	// TODO: set_alpha_blender
+	trans_blend_alpha = -1;
 }
 
 void set_write_alpha_blender(void) {
@@ -281,7 +282,8 @@ void set_write_alpha_blender(void) {
 }
 
 void set_trans_blender(int r, int g, int b, int a) {
-	// TODO: set_trans_blender
+	assert(r == 0 && g == 0 && b == 0);
+	trans_blend_alpha = a;
 }
 
 void set_add_blender(int r, int g, int b, int a) {
diff --git a/engines/ags/lib/allegro/color.h b/engines/ags/lib/allegro/color.h
index 8c9922502e..870d7d756c 100644
--- a/engines/ags/lib/allegro/color.h
+++ b/engines/ags/lib/allegro/color.h
@@ -77,6 +77,7 @@ AL_VAR(PALETTE, default_palette);
 
 AL_VAR(RGB_MAP *, rgb_map);
 AL_VAR(COLOR_MAP *, color_map);
+extern int trans_blend_alpha;
 
 AL_VAR(PALETTE, _current_palette);
 
diff --git a/engines/ags/lib/allegro/gfx.cpp b/engines/ags/lib/allegro/gfx.cpp
index cc7faadab9..bc7d401417 100644
--- a/engines/ags/lib/allegro/gfx.cpp
+++ b/engines/ags/lib/allegro/gfx.cpp
@@ -21,6 +21,7 @@
  */
 
 #include "ags/lib/allegro/gfx.h"
+#include "ags/lib/allegro/color.h"
 #include "ags/lib/allegro/flood.h"
 #include "ags/ags.h"
 #include "common/textconsole.h"
@@ -35,10 +36,13 @@ int color_conversion;
 #define TRANSPARENT_COLOR(BITMAP) ((BITMAP).format.bytesPerPixel == 1 ? 0 : \
 	(BITMAP).format.RGBToColor(255, 0, 255))
 
+// Arbitrary RGBA tuplet that should never be encountered
+#define NO_TRANSPARENT_COLOR 0x88888888
+
 /*-------------------------------------------------------------------*/
 
 BITMAP::BITMAP(Graphics::ManagedSurface *owner) : _owner(owner),
-		w(owner->w), h(owner->h), format(owner->format),
+		w(owner->w), h(owner->h), pitch(owner->pitch), format(owner->format),
 		clip(false), ct(0), cl(0), cr(owner->w), cb(owner->h) {
 	line.resize(h);
 	for (uint y = 0; y < h; ++y)
@@ -303,7 +307,28 @@ void stretch_sprite(BITMAP *bmp, const BITMAP *sprite, int x, int y, int w, int
 }
 
 void draw_trans_sprite(BITMAP *bmp, const BITMAP *sprite, int x, int y) {
-	bmp->getSurface().blitFrom(sprite->getSurface(), Common::Point(x, y));
+	assert(sprite->format.bytesPerPixel == 4);
+
+	if (trans_blend_alpha == -1) {
+		bmp->getSurface().blitFrom(sprite->getSurface(), Common::Point(x, y));
+
+	} else {
+		// Create a temporary ManagedSurface with a pointer to the sprite's pixels,
+		// and a pixel format that matches the sprite, but has no alpha.
+		// This will prevent it being applied from the sprite in transBlitFrom
+		Graphics::ManagedSurface spr;
+		spr.format = sprite->format;
+		spr.format.aLoss = 8;
+		spr.format.aShift = 0;
+		spr.setPixels(sprite->getPixels());
+		spr.w = sprite->w;
+		spr.h = sprite->h;
+		spr.pitch = sprite->pitch;
+
+		bmp->getSurface().transBlitFrom(spr, Common::Rect(0, 0, spr.w, spr.h),
+			Common::Rect(x, y, x + spr.w, y + spr.h), NO_TRANSPARENT_COLOR,
+			false, 0, trans_blend_alpha);
+	}
 }
 
 void draw_lit_sprite(BITMAP *bmp, const BITMAP *sprite, int x, int y, int color) {
diff --git a/engines/ags/lib/allegro/gfx.h b/engines/ags/lib/allegro/gfx.h
index dfa900e46a..91c9f62ce1 100644
--- a/engines/ags/lib/allegro/gfx.h
+++ b/engines/ags/lib/allegro/gfx.h
@@ -177,7 +177,7 @@ class BITMAP {
 private:
 	Graphics::ManagedSurface *_owner;
 public:
-	uint16 &w, &h;
+	uint16 &w, &h, &pitch;
 	Graphics::PixelFormat &format;
 	bool clip;
 	int ct, cb, cl, cr;