Shader: Refine preprocessing on GLES platform

Don't globally set float precision to mediump, only fragment
shaders need that and defining it for vertex shaders causes
tilemap cracks.

Also manually define low precision for variables that hold
color / alpha values.

CMakeLists.txt

@@ -210,6 +210,7 @@ source_group("MKXP Source" FILES ${MAIN_SOURCE} ${MAIN_HEADERS})
 ## Setup embedded source ##
 
 set(EMBEDDED_INPUT
+	shader/common.h
 	shader/transSimple.frag
 	shader/trans.frag
 	shader/hue.frag

mkxp.pro

@@ -183,6 +183,7 @@ SOURCES += \
 	src/fluid-fun.cpp
 
 EMBED = \
+	shader/common.h \
 	shader/transSimple.frag \
 	shader/trans.frag \
 	shader/hue.frag \

shader/bitmapBlit.frag

@@ -6,7 +6,7 @@ uniform sampler2D destination;
 
 uniform vec4 subRect;
 
-uniform float opacity;
+uniform lowp float opacity;
 
 varying vec2 v_texCoord;
 

shader/blur.frag

@@ -6,7 +6,7 @@ varying vec2 v_blurCoord[2];
 
 void main()
 {
-	vec4 frag = vec4(0, 0, 0, 0);
+	lowp vec4 frag = vec4(0, 0, 0, 0);
 
 	frag += texture2D(texture, v_texCoord);
 	frag += texture2D(texture, v_blurCoord[0]);

shader/common.h

@@ -0,0 +1,15 @@
+#ifdef GLSLES
+
+#ifdef FRAGMENT_SHADER
+/* Only the fragment shader has no default float precision */
+precision mediump float;
+#endif
+
+#else
+
+/* Desktop GLSL doesn't know about these */
+#define highp
+#define mediump
+#define lowp
+
+#endif

shader/flashMap.frag

@@ -1,7 +1,7 @@
 
-uniform float alpha;
+uniform lowp float alpha;
 
-varying vec4 v_color;
+varying lowp vec4 v_color;
 
 void main()
 {

shader/plane.frag

@@ -1,11 +1,11 @@
 
 uniform sampler2D texture;
 
-uniform vec4 tone;
+uniform lowp vec4 tone;
 
-uniform float opacity;
-uniform vec4 color;
-uniform vec4 flash;
+uniform lowp float opacity;
+uniform lowp vec4 color;
+uniform lowp vec4 flash;
 
 varying vec2 v_texCoord;
 

shader/simpleAlpha.frag

@@ -2,7 +2,7 @@
 uniform sampler2D texture;
 
 varying vec2 v_texCoord;
-varying vec4 v_color;
+varying lowp vec4 v_color;
 
 void main()
 {

shader/simpleColor.frag

@@ -1,5 +1,5 @@
 
-varying vec4 v_color;
+varying lowp vec4 v_color;
 
 void main()
 {

shader/simpleColor.vert

@@ -6,10 +6,10 @@ uniform vec2 translation;
 
 attribute vec2 position;
 attribute vec2 texCoord;
-attribute vec4 color;
+attribute lowp vec4 color;
 
 varying vec2 v_texCoord;
-varying vec4 v_color;
+varying lowp vec4 v_color;
 
 void main()
 {

shader/simpleMatrix.vert

@@ -6,10 +6,10 @@ uniform vec2 texSizeInv;
 
 attribute vec2 position;
 attribute vec2 texCoord;
-attribute vec4 color;
+attribute lowp vec4 color;
 
 varying vec2 v_texCoord;
-varying vec4 v_color;
+varying lowp vec4 v_color;
 
 void main()
 {

shader/sprite.frag

@@ -1,13 +1,13 @@
 
 uniform sampler2D texture;
 
-uniform vec4 tone;
+uniform lowp vec4 tone;
 
-uniform float opacity;
-uniform vec4 color;
+uniform lowp float opacity;
+uniform lowp vec4 color;
 
 uniform float bushDepth;
-uniform float bushOpacity;
+uniform lowp float bushOpacity;
 
 varying vec2 v_texCoord;
 
@@ -32,7 +32,7 @@ void main()
 	frag.rgb = mix(frag.rgb, color.rgb, color.a);
 
 	/* Apply bush alpha by mathematical if */
-	float underBush = float(v_texCoord.y < bushDepth);
+	lowp float underBush = float(v_texCoord.y < bushDepth);
 	frag.a *= clamp(bushOpacity + underBush, 0.0, 1.0);
 	
 	gl_FragColor = frag;

shader/trans.frag

@@ -14,7 +14,7 @@ void main()
 {
     float transV = texture2D(transMap, v_texCoord).r;
     float cTransV = clamp(transV, prog, prog+vague);
-    float alpha = (cTransV - prog) / vague;
+    lowp float alpha = (cTransV - prog) / vague;
     
     vec4 newFrag = texture2D(currentScene, v_texCoord);
     vec4 oldFrag = texture2D(frozenScene, v_texCoord);

src/shader.cpp

@@ -28,6 +28,7 @@
 #include <string.h>
 #include <iostream>
 
+#include "common.h.xxd"
 #include "sprite.frag.xxd"
 #include "hue.frag.xxd"
 #include "trans.frag.xxd"
@@ -106,32 +107,39 @@ void Shader::unbind()
 	glState.program.set(0);
 }
 
-static const char *glesHeader = "precision mediump float;\n";
-static const size_t glesHeaderSize = strlen(glesHeader);
-
-static void setupShaderSource(GLuint shader,
-                              const unsigned char *src, int srcSize)
+static void setupShaderSource(GLuint shader, GLenum type,
+                              const unsigned char *body, int bodySize)
 {
-	GLuint shaderSrcN;
-	const GLchar *shaderSrc[2];
-	GLint shaderSrcSize[2];
+	static const char glesDefine[] = "#define GLSLES\n";
+	static const char fragDefine[] = "#define FRAGMENT_SHADER\n";
+
+	const GLchar *shaderSrc[4];
+	GLint shaderSrcSize[4];
+	size_t i = 0;
 
 	if (gl.glsles)
 	{
-		shaderSrcN = 2;
-		shaderSrc[0] = glesHeader;
-		shaderSrc[1] = (const GLchar*) src;
-		shaderSrcSize[0] = glesHeaderSize;
-		shaderSrcSize[1] = srcSize;
-	}
-	else
-	{
-		shaderSrcN = 1;
-		shaderSrc[0] = (const GLchar*) src;
-		shaderSrcSize[0] = srcSize;
+		shaderSrc[i] = glesDefine;
+		shaderSrcSize[i] = sizeof(glesDefine)-1;
+		++i;
 	}
 
-	gl.ShaderSource(shader, shaderSrcN, shaderSrc, shaderSrcSize);
+	if (type == GL_FRAGMENT_SHADER)
+	{
+		shaderSrc[i] = fragDefine;
+		shaderSrcSize[i] = sizeof(fragDefine)-1;
+		++i;
+	}
+
+	shaderSrc[i] = (const GLchar*) shader_common_h;
+	shaderSrcSize[i] = shader_common_h_len;
+	++i;
+
+	shaderSrc[i] = (const GLchar*) body;
+	shaderSrcSize[i] = bodySize;
+	++i;
+
+	gl.ShaderSource(shader, i, shaderSrc, shaderSrcSize);
 }
 
 void Shader::init(const unsigned char *vert, int vertSize,
@@ -142,7 +150,7 @@ void Shader::init(const unsigned char *vert, int vertSize,
 	GLint success;
 
 	/* Compile vertex shader */
-	setupShaderSource(vertShader, vert, vertSize);
+	setupShaderSource(vertShader, GL_VERTEX_SHADER, vert, vertSize);
 	gl.CompileShader(vertShader);
 
 	gl.GetShaderiv(vertShader, GL_COMPILE_STATUS, &success);
@@ -156,7 +164,7 @@ void Shader::init(const unsigned char *vert, int vertSize,
 	}
 
 	/* Compile fragment shader */
-	setupShaderSource(fragShader, frag, fragSize);
+	setupShaderSource(fragShader, GL_FRAGMENT_SHADER, frag, fragSize);
 	gl.CompileShader(fragShader);
 
 	gl.GetShaderiv(fragShader, GL_COMPILE_STATUS, &success);