Improved GLSL precision specifiers in GL 2 engine.

The recommended specifiers are lowp for colors / normal vectors, mediump
for texture coordinates when a limited range is sufficient, and highp
for generic texture coordinates and vertex coordinates / transformation
matrices.

We used to use mediump for texture coordinate in some places, but
since we don't control the texturing scenarios we need to handle the
worst case, which is zooming in on part of a large texture (2048x2048)
with bilinear filtering. To properly handle this case without color
banding mediump is probably not sufficient, so we'll use highp for
texture coordinates.

Reviewed-by: Tom

1 files changed, 24 insertions, 24 deletions

diff --git a/src/opengl/gl2paintengineex/qglengineshadersource_p.h b/src/opengl/gl2paintengineex/qglengineshadersource_p.h
index a8e2e72..cd3cf57 100644
--- a/src/opengl/gl2paintengineex/qglengineshadersource_p.h
+++ b/src/opengl/gl2paintengineex/qglengineshadersource_p.h
@@ -73,8 +73,8 @@ static const char* const qglslMainVertexShader = "\
     }";
 
 static const char* const qglslMainWithTexCoordsVertexShader = "\
-    attribute mediump  vec2 textureCoordArray; \
-    varying   mediump  vec2 textureCoords; \
+    attribute highp  vec2 textureCoordArray; \
+    varying   highp  vec2 textureCoords; \
     uniform   highp float   depth;\
     void setPosition();\
     void main(void) \
@@ -105,9 +105,9 @@ static const char* const qglslPositionWithPatternBrushVertexShader = "\
     attribute highp   vec4  vertexCoordsArray; \
     uniform   highp   mat4  pmvMatrix; \
     uniform   mediump vec2  halfViewportSize; \
-    uniform   mediump vec2  invertedTextureSize; \
-    uniform   mediump mat3  brushTransform; \
-    varying   mediump vec2  patternTexCoords; \
+    uniform   highp   vec2  invertedTextureSize; \
+    uniform   highp   mat3  brushTransform; \
+    varying   highp   vec2  patternTexCoords; \
     void setPosition(void) { \
             gl_Position = pmvMatrix * vertexCoordsArray;\
             gl_Position.xy = gl_Position.xy / gl_Position.w; \
@@ -124,9 +124,9 @@ static const char* const qglslAffinePositionWithPatternBrushVertexShader
                  = qglslPositionWithPatternBrushVertexShader;
 
 static const char* const qglslPatternBrushSrcFragmentShader = "\
-    uniform         sampler2D brushTexture;\
+    uniform lowp    sampler2D brushTexture;\
     uniform lowp    vec4      patternColor; \
-    varying mediump vec2      patternTexCoords;\
+    varying highp   vec2      patternTexCoords;\
     lowp vec4 srcPixel() { \
         return patternColor * (1.0 - texture2D(brushTexture, patternTexCoords).r); \
     }\n";
@@ -139,7 +139,7 @@ static const char* const qglslPositionWithLinearGradientBrushVertexShader = "\
     uniform   mediump vec2  halfViewportSize; \
     uniform   highp   vec3  linearData; \
     uniform   highp   mat3  brushTransform; \
-    varying   mediump float index ; \
+    varying   mediump float index; \
     void setPosition() { \
         gl_Position = pmvMatrix * vertexCoordsArray;\
         gl_Position.xy = gl_Position.xy / gl_Position.w; \
@@ -155,7 +155,7 @@ static const char* const qglslAffinePositionWithLinearGradientBrushVertexShader
                  = qglslPositionWithLinearGradientBrushVertexShader;
 
 static const char* const qglslLinearGradientBrushSrcFragmentShader = "\
-    uniform         sampler2D   brushTexture; \
+    uniform lowp    sampler2D   brushTexture; \
     varying mediump float       index; \
     lowp vec4 srcPixel() { \
         mediump vec2 val = vec2(index, 0.5); \
@@ -187,7 +187,7 @@ static const char* const qglslAffinePositionWithConicalGradientBrushVertexShader
 
 static const char* const qglslConicalGradientBrushSrcFragmentShader = "\n\
     #define INVERSE_2PI 0.1591549430918953358 \n\
-    uniform         sampler2D   brushTexture; \n\
+    uniform lowp    sampler2D   brushTexture; \n\
     uniform mediump float       angle; \
     varying highp   vec2        A; \
     lowp vec4 srcPixel() { \
@@ -226,7 +226,7 @@ static const char* const qglslAffinePositionWithRadialGradientBrushVertexShader
                  = qglslPositionWithRadialGradientBrushVertexShader;
 
 static const char* const qglslRadialGradientBrushSrcFragmentShader = "\
-    uniform         sampler2D   brushTexture; \
+    uniform lowp    sampler2D   brushTexture; \
     uniform highp   float       fmp2_m_radius2; \
     uniform highp   float       inverse_2_fmp2_m_radius2; \
     varying highp   float       b; \
@@ -243,9 +243,9 @@ static const char* const qglslPositionWithTextureBrushVertexShader = "\
     attribute highp   vec4  vertexCoordsArray; \
     uniform   highp   mat4  pmvMatrix; \
     uniform   mediump vec2  halfViewportSize; \
-    uniform   mediump vec2  invertedTextureSize; \
-    uniform   mediump mat3  brushTransform; \
-    varying   mediump vec2  brushTextureCoords; \
+    uniform   highp   vec2  invertedTextureSize; \
+    uniform   highp   mat3  brushTransform; \
+    varying   highp   vec2  brushTextureCoords; \
     void setPosition(void) { \
             gl_Position = pmvMatrix * vertexCoordsArray;\
             gl_Position.xy = gl_Position.xy / gl_Position.w; \
@@ -262,16 +262,16 @@ static const char* const qglslAffinePositionWithTextureBrushVertexShader
                  = qglslPositionWithTextureBrushVertexShader;
 
 static const char* const qglslTextureBrushSrcFragmentShader = "\
-    varying mediump vec2      brushTextureCoords; \
-    uniform         sampler2D brushTexture; \
+    varying highp   vec2      brushTextureCoords; \
+    uniform lowp    sampler2D brushTexture; \
     lowp vec4 srcPixel() { \
         return texture2D(brushTexture, brushTextureCoords); \
     }";
 
 static const char* const qglslTextureBrushSrcWithPatternFragmentShader = "\
-    varying mediump vec2      brushTextureCoords; \
+    varying highp   vec2      brushTextureCoords; \
     uniform lowp    vec4      patternColor; \
-    uniform         sampler2D brushTexture; \
+    uniform lowp    sampler2D brushTexture; \
     lowp vec4 srcPixel() { \
         return patternColor * (1.0 - texture2D(brushTexture, brushTextureCoords).r); \
     }";
@@ -284,15 +284,15 @@ static const char* const qglslSolidBrushSrcFragmentShader = "\
     }";
 
 static const char* const qglslImageSrcFragmentShader = "\
-    varying mediump vec2    textureCoords; \
-    uniform       sampler2D imageTexture; \
+    varying highp   vec2    textureCoords; \
+    uniform lowp  sampler2D imageTexture; \
     lowp vec4 srcPixel() { \
         return texture2D(imageTexture, textureCoords); \
     }";
 
 static const char* const qglslCustomSrcFragmentShader = "\
     varying highp vec2      textureCoords; \
-    uniform       sampler2D imageTexture; \
+    uniform lowp  sampler2D imageTexture; \
     lowp vec4 customShader(lowp sampler2D texture, highp vec2 coords); \
     lowp vec4 srcPixel() { \
         return customShader(imageTexture, textureCoords); \
@@ -301,14 +301,14 @@ static const char* const qglslCustomSrcFragmentShader = "\
 static const char* const qglslImageSrcWithPatternFragmentShader = "\
     varying highp vec2      textureCoords; \
     uniform lowp  vec4      patternColor; \
-    uniform       sampler2D imageTexture; \
+    uniform lowp  sampler2D imageTexture; \
     lowp vec4 srcPixel() { \
         return patternColor * (1.0 - texture2D(imageTexture, textureCoords).r); \
     }\n";
 
 static const char* const qglslNonPremultipliedImageSrcFragmentShader = "\
     varying highp vec2      textureCoords; \
-    uniform       sampler2D imageTexture; \
+    uniform lowp  sampler2D imageTexture; \
     lowp vec4 srcPixel() { \
         lowp vec4 sample = texture2D(imageTexture, textureCoords); \
         sample.rgb = sample.rgb * sample.a; \
@@ -383,7 +383,7 @@ static const char* const qglslMainFragmentShader = "\
 
 static const char* const qglslMaskFragmentShader = "\
     varying highp   vec2      textureCoords;\
-    uniform         sampler2D maskTexture;\
+    uniform lowp    sampler2D maskTexture;\
     lowp vec4 applyMask(lowp vec4 src) \
     {\
         lowp vec4 mask = texture2D(maskTexture, textureCoords); \