Implement DrawGraph.CopyColorReverse

Just a copy operation that inverts colors. Used in Rance VI Sonogo.

include/gfx/gfx.h

@@ -99,6 +99,7 @@ void gfx_copy(struct texture *dst, int dx, int dy, struct texture *src, int sx,
 void gfx_copy_bright(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h, int rate);
 void gfx_copy_amap(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h);
 void gfx_copy_sprite(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h, SDL_Color color);
+void gfx_copy_color_reverse(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h);
 void gfx_copy_use_amap_under(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h, int threshold);
 void gfx_copy_use_amap_border(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h, int threshold);
 void gfx_copy_amap_max(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h);

shaders/copy_color_reverse.f.glsl

@@ -0,0 +1,27 @@
+/* Copyright (C) 2019 Nunuhara Cabbage <nunuhara@haniwa.technology>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://gnu.org/licenses/>.
+ */
+
+#version 140
+
+uniform sampler2D tex;
+
+in vec2 tex_coord;
+out vec4 frag_color;
+
+void main() {
+        vec4 texel = texture(tex, tex_coord);
+        frag_color = vec4(1.0 - texel.r, 1.0 - texel.g, 1.0 - texel.b, 1);
+}

src/draw.c

@@ -55,6 +55,7 @@ struct copy_data {
 	STRETCH_DATA(_dx, _dy, _w, _h, _sx, _sy, _w, _h)
 
 static struct copy_shader copy_shader;
+static struct copy_shader copy_color_reverse_shader;
 static struct copy_shader copy_key_shader;
 static struct copy_shader copy_use_amap_under_shader;
 static struct copy_shader copy_use_amap_border_shader;
@@ -90,6 +91,9 @@ void gfx_draw_init(void)
 	// generic copy shader; discards fragments outside of a given rectangle
 	load_copy_shader(&copy_shader, "shaders/render.v.glsl", "shaders/copy.f.glsl");
 
+	// copy shader which inverts colors
+	load_copy_shader(&copy_color_reverse_shader, "shaders/render.v.glsl", "shaders/copy_color_reverse.f.glsl");
+
 	// copy shader which also discards fragments matching a color key
 	load_copy_shader(&copy_key_shader, "shaders/render.v.glsl", "shaders/copy_key.f.glsl");
 
@@ -206,6 +210,16 @@ void gfx_copy_sprite(Texture *dst, int dx, int dy, Texture *src, int sx, int sy,
 	restore_blend_mode();
 }
 
+void gfx_copy_color_reverse(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h)
+{
+	glBlendFuncSeparate(GL_ONE, GL_ZERO, GL_ZERO, GL_ONE);
+
+	struct copy_data data = COPY_DATA(dx, dy, sx, sy, w, h);
+	run_copy_shader(&copy_color_reverse_shader.s, dst, src, &data);
+
+	restore_blend_mode();
+}
+
 void gfx_copy_use_amap_under(Texture *dst, int dx, int dy, Texture *src, int sx, int sy, int w, int h, int threshold)
 {
 	glBlendFuncSeparate(GL_ONE, GL_ZERO, GL_ZERO, GL_ONE);

src/hll/DrawGraph.c

@@ -42,6 +42,11 @@ static void DrawGraph_CopySprite(int dst, int dx, int dy, int src, int sx, int s
 	gfx_copy_sprite(DTEX(dst), dx, dy, STEX(src), sx, sy, w, h, COLOR(r, g, b, 0));
 }
 
+static void DrawGraph_CopyColorReverse(int dst, int dx, int dy, int src, int sx, int sy, int w, int h)
+{
+	gfx_copy_color_reverse(DTEX(dst), dx, dy, STEX(src), sx, sy, w, h);
+}
+
 static void DrawGraph_CopyUseAMapUnder(int dst, int dx, int dy, int src, int sx, int sy, int w, int h, int alpha)
 {
 	gfx_copy_use_amap_under(DTEX(dst), dx, dy, STEX(src), sx, sy, w, h, alpha);
@@ -166,7 +171,6 @@ static void DrawGraph_SetFontName(struct string *text)
 	gfx_set_font_name(text->text);
 }
 
-//void DrawGraph_CopyColorReverse(int dst, int dx, int dy, int src, int sx, int sy, int w, int h);
 //void DrawGraph_BlendSrcBright(int dst, int dx, int dy, int src, int sx, int sy, int w, int h, int alpha, int rate);
 //void DrawGraph_BlendAddSatur(int dst, int dx, int dy, int src, int sx, int sy, int w, int h);
 //void DrawGraph_BlendAMapSrcOnly(int dst, int dx, int dy, int src, int sx, int sy, int w, int h);
@@ -225,7 +229,7 @@ HLL_LIBRARY(DrawGraph,
 	    HLL_EXPORT(CopyBright, DrawGraph_CopyBright),
 	    HLL_EXPORT(CopyAMap, DrawGraph_CopyAMap),
 	    HLL_EXPORT(CopySprite, DrawGraph_CopySprite),
-	    //HLL_EXPORT(CopyColorReverse, DrawGraph_CopyColorReverse),
+	    HLL_EXPORT(CopyColorReverse, DrawGraph_CopyColorReverse),
 	    HLL_EXPORT(CopyUseAMapUnder, DrawGraph_CopyUseAMapUnder),
 	    HLL_EXPORT(CopyUseAMapBorder, DrawGraph_CopyUseAMapBorder),
 	    HLL_EXPORT(CopyAMapMax, DrawGraph_CopyAMapMax),