gsdx-ogl: depth support: better support of 16 bits z buffer

Fix issue in socom2

plugins/GSdx/GSDeviceOGL.cpp

@@ -940,7 +940,7 @@ void GSDeviceOGL::StretchRect(GSTexture* sTex, const GSVector4& sRect, GSTexture
 		return;
 	}
 
-	bool draw_in_depth = (ps == m_convert.ps[12] || ps == m_convert.ps[13]);
+	bool draw_in_depth = (ps == m_convert.ps[12] || ps == m_convert.ps[13] || ps == m_convert.ps[14]);
 
 	// Performance optimization. It might be faster to use a framebuffer blit for standard case
 	// instead to emulate it with shader

plugins/GSdx/GSDeviceOGL.h

@@ -500,7 +500,7 @@ class GSDeviceOGL : public GSDevice
 
 	struct {
 		GLuint vs;		// program object
-		GLuint ps[15];	// program object
+		GLuint ps[16];	// program object
 		GLuint ln;		// sampler object
 		GLuint pt;		// sampler object
 		GSDepthStencilOGL* dss;

plugins/GSdx/GSTextureCache.cpp

@@ -283,7 +283,8 @@ GSTextureCache::Target* GSTextureCache::LookupTarget(const GIFRegTEX0& TEX0, int
 
 				if (type == DepthStencil) {
 					GL_CACHE("TC: Lookup Target(Depth) %dx%d, hit Color (0x%x, F:0x%x)", w, h, bp, TEX0.PSM);
-					int shader = (TEX0.PSM & 1) ? 13 : 12;
+					int shader = 12 + GSLocalMemory::m_psm[TEX0.PSM].fmt;
+					ASSERT(shader <= 14);
 					m_renderer->m_dev->StretchRect(t->m_texture, sRect, dst->m_texture, dRect, shader, false);
 				} else {
 					GL_CACHE("TC: Lookup Target(Color) %dx%d, hit Depth (0x%x, F:0x%x)", w, h, bp, TEX0.PSM);
@@ -861,7 +862,7 @@ GSTextureCache::Source* GSTextureCache::CreateSource(const GIFRegTEX0& TEX0, con
 
 		if (is_8bits) {
 			GL_INS("Reading RT as a packed-indexed 8 bits format");
-			shader = 14; // ask a conversion to 8 bits format
+			shader = 15; // ask a conversion to 8 bits format
 		}
 
 #ifdef ENABLE_OGL_DEBUG

plugins/GSdx/res/glsl/convert.glsl

@@ -194,17 +194,30 @@ void ps_main12()
 //out float gl_FragDepth;
 void ps_main13()
 {
-	// Same as above but without the alpha channel
+	// Same as above but without the alpha channel (24 bits Z)
 
 	// Convert a RRGBA texture into a float depth texture
 	// FIXME: I'm afraid of the accuracy
-	const vec4 bitSh = vec4(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0), 1.0/256.0, 0.0) * vec4(255.0/256.0);
+	const vec3 bitSh = vec3(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0), 1.0/256.0) * vec3(255.0/256.0);
-	gl_FragDepth = dot(sample_c(), bitSh);
+	gl_FragDepth = dot(sample_c().rgb, bitSh);
 }
 #endif
 
 #ifdef ps_main14
+//out float gl_FragDepth;
 void ps_main14()
+{
+	// Same as above but without the A/B channels (16 bits Z)
+
+	// Convert a RRGBA texture into a float depth texture
+	// FIXME: I'm afraid of the accuracy
+	const vec2 bitSh = vec2(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0)) * vec2(255.0/256.0);
+	gl_FragDepth = dot(sample_c().rg, bitSh);
+}
+#endif
+
+#ifdef ps_main15
+void ps_main15()
 {
 
     // Potential speed optimization. There is a high probability that

plugins/GSdx/res/glsl_source.h

@@ -219,18 +219,31 @@ static const char* convert_glsl =
 	"//out float gl_FragDepth;\n"
 	"void ps_main13()\n"
 	"{\n"
-	"	// Same as above but without the alpha channel\n"
+	"	// Same as above but without the alpha channel (24 bits Z)\n"
 	"\n"
 	"	// Convert a RRGBA texture into a float depth texture\n"
 	"	// FIXME: I'm afraid of the accuracy\n"
-	"	const vec4 bitSh = vec4(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0), 1.0/256.0, 0.0) * vec4(255.0/256.0);\n"
+	"	const vec3 bitSh = vec3(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0), 1.0/256.0) * vec3(255.0/256.0);\n"
-	"	gl_FragDepth = dot(sample_c(), bitSh);\n"
+	"	gl_FragDepth = dot(sample_c().rgb, bitSh);\n"
 	"}\n"
 	"#endif\n"
 	"\n"
 	"#ifdef ps_main14\n"
+	"//out float gl_FragDepth;\n"
 	"void ps_main14()\n"
 	"{\n"
+	"	// Same as above but without the A/B channels (16 bits Z)\n"
+	"\n"
+	"	// Convert a RRGBA texture into a float depth texture\n"
+	"	// FIXME: I'm afraid of the accuracy\n"
+	"	const vec2 bitSh = vec2(1.0/(256.0*256.0*256.0), 1.0/(256.0*256.0)) * vec2(255.0/256.0);\n"
+	"	gl_FragDepth = dot(sample_c().rg, bitSh);\n"
+	"}\n"
+	"#endif\n"
+	"\n"
+	"#ifdef ps_main15\n"
+	"void ps_main15()\n"
+	"{\n"
 	"\n"
 	"    // Potential speed optimization. There is a high probability that\n"
 	"    // game only want to extract a single channel (blue). It will allow\n"