[PATCH xserver 4/4] glamor: tidy up some gradient color formulas
Jeff Smith
whydoubt at gmail.com
Fri Jan 26 12:25:22 UTC 2018
- Avoid some needlessly complex equations for calculating the color at a
point in a gradient field.
- Avoid calculating certain values multiple times.
- Use similar variable names across the two versions of the get_color
function where practical.
Signed-off-by: Jeff Smith <whydoubt at gmail.com>
---
glamor/glamor_gradient.c | 66 ++++++++++++++++++++++--------------------------
1 file changed, 30 insertions(+), 36 deletions(-)
diff --git a/glamor/glamor_gradient.c b/glamor/glamor_gradient.c
index 864340e77..4e864cd79 100644
--- a/glamor/glamor_gradient.c
+++ b/glamor/glamor_gradient.c
@@ -52,8 +52,9 @@ _glamor_create_getcolor_fs_source(ScreenPtr screen, int stops_count,
"vec4 get_color(float stop_len)\n"\
"{\n"\
" int i = 0;\n"\
- " float new_alpha; \n"\
+ " vec4 stop_color_before;\n"\
" vec4 gradient_color;\n"\
+ " float stop_delta;\n"\
" float percentage; \n"\
" \n"\
" if(stop_len < stops[0])\n"\
@@ -65,19 +66,19 @@ _glamor_create_getcolor_fs_source(ScreenPtr screen, int stops_count,
" if(i == n_stop)\n"\
" return vec4(0.0, 0.0, 0.0, 0.0); \n"\
" \n"\
- " if(stops[i] - stops[i-1] > 2.0)\n"\
+ " stop_color_before = stop_colors[i-1];\n"\
+ " stop_delta = stops[i] - stops[i-1];\n"\
+ " if(stop_delta > 2.0)\n"\
" percentage = 0.0;\n" /*For comply with pixman, walker->stepper overflow.*/\
- " else if(stops[i] - stops[i-1] < 0.000001)\n"\
+ " else if(stop_delta < 0.000001)\n"\
" percentage = 0.0;\n"\
" else \n"\
- " percentage = (stop_len - stops[i-1])/(stops[i] - stops[i-1]);\n"\
- " new_alpha = percentage * stop_colors[i].a + \n"\
- " (1.0-percentage) * stop_colors[i-1].a; \n"\
- " gradient_color = vec4((percentage * stop_colors[i].rgb \n"\
- " + (1.0-percentage) * stop_colors[i-1].rgb)*new_alpha, \n"\
- " new_alpha);\n"\
+ " percentage = (stop_len - stops[i-1])/stop_delta;\n"\
" \n"\
- " return gradient_color;\n"\
+ " gradient_color = stop_color_before;\n"\
+ " if(percentage != 0.0)\n"\
+ " gradient_color += (stop_colors[i] - gradient_color)*percentage;\n"\
+ " return vec4(gradient_color.rgb * gradient_color.a, gradient_color.a);\n"\
"}\n"
/* Because the array access for shader is very slow, the performance is very low
@@ -104,73 +105,66 @@ _glamor_create_getcolor_fs_source(ScreenPtr screen, int stops_count,
"\n"
"vec4 get_color(float stop_len)\n"
"{\n"
- " float stop_after;\n"
- " float stop_before;\n"
" vec4 stop_color_before;\n"
" vec4 stop_color_after;\n"
- " float new_alpha; \n"
" vec4 gradient_color;\n"
+ " float stop_before;\n"
+ " float stop_delta;\n"
" float percentage; \n"
" \n"
" if((stop_len < stop0) && (n_stop >= 1)) {\n"
" stop_color_before = vec4(0.0, 0.0, 0.0, 0.0);\n"
- " stop_color_after = vec4(0.0, 0.0, 0.0, 0.0);\n"
- " stop_after = 0.0;\n"
- " stop_before = 0.0;\n"
+ " stop_delta = 0.0;\n"
" } else if((stop_len < stop1) && (n_stop >= 2)) {\n"
" stop_color_before = stop_color0;\n"
" stop_color_after = stop_color1;\n"
- " stop_after = stop1;\n"
" stop_before = stop0;\n"
+ " stop_delta = stop1 - stop0;\n"
" } else if((stop_len < stop2) && (n_stop >= 3)) {\n"
" stop_color_before = stop_color1;\n"
" stop_color_after = stop_color2;\n"
- " stop_after = stop2;\n"
" stop_before = stop1;\n"
+ " stop_delta = stop2 - stop1;\n"
" } else if((stop_len < stop3) && (n_stop >= 4)){\n"
" stop_color_before = stop_color2;\n"
" stop_color_after = stop_color3;\n"
- " stop_after = stop3;\n"
" stop_before = stop2;\n"
+ " stop_delta = stop3 - stop2;\n"
" } else if((stop_len < stop4) && (n_stop >= 5)){\n"
" stop_color_before = stop_color3;\n"
" stop_color_after = stop_color4;\n"
- " stop_after = stop4;\n"
" stop_before = stop3;\n"
+ " stop_delta = stop4 - stop3;\n"
" } else if((stop_len < stop5) && (n_stop >= 6)){\n"
" stop_color_before = stop_color4;\n"
" stop_color_after = stop_color5;\n"
- " stop_after = stop5;\n"
" stop_before = stop4;\n"
+ " stop_delta = stop5 - stop4;\n"
" } else if((stop_len < stop6) && (n_stop >= 7)){\n"
" stop_color_before = stop_color5;\n"
" stop_color_after = stop_color6;\n"
- " stop_after = stop6;\n"
" stop_before = stop5;\n"
+ " stop_delta = stop6 - stop5;\n"
" } else if((stop_len < stop7) && (n_stop >= 8)){\n"
" stop_color_before = stop_color6;\n"
" stop_color_after = stop_color7;\n"
- " stop_after = stop7;\n"
" stop_before = stop6;\n"
+ " stop_delta = stop7 - stop6;\n"
" } else {\n"
" stop_color_before = vec4(0.0, 0.0, 0.0, 0.0);\n"
- " stop_color_after = vec4(0.0, 0.0, 0.0, 0.0);\n"
- " stop_after = 0.0;\n"
- " stop_before = 0.0;\n"
+ " stop_delta = 0.0;\n"
" }\n"
- " if(stop_after - stop_before > 2.0)\n"
+ " if(stop_delta > 2.0)\n"
" percentage = 0.0;\n" //For comply with pixman, walker->stepper overflow.
- " else if(stop_after - stop_before < 0.000001)\n"
+ " else if(stop_delta < 0.000001)\n"
" percentage = 0.0;\n"
- " else \n"
- " percentage = (stop_len - stop_before)/(stop_after - stop_before);\n"
- " new_alpha = percentage * stop_color_after.a + \n"
- " (1.0-percentage) * stop_color_before.a; \n"
- " gradient_color = vec4((percentage * stop_color_after.rgb \n"
- " + (1.0-percentage) * stop_color_before.rgb)*new_alpha, \n"
- " new_alpha);\n"
+ " else\n"
+ " percentage = (stop_len - stop_before)/stop_delta;\n"
" \n"
- " return gradient_color;\n"
+ " gradient_color = stop_color_before;\n"
+ " if(percentage != 0.0)\n"
+ " gradient_color += (stop_color_after - gradient_color)*percentage;\n"
+ " return vec4(gradient_color.rgb * gradient_color.a, gradient_color.a);\n"
"}\n";
if (use_array) {
--
2.14.3
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