gl-renderer: consolidate linpow sampling GLSL

This is pure refactoring.

Ease readability by reducing code duplication between pre and post curve
linpow handling.

While at it, define symbols for the counts. This patch converts only
linpow. Powlin are converted in follow-up.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

1 files changed, 32 insertions, 42 deletions

diff --git a/libweston/renderer-gl/fragment.glsl b/libweston/renderer-gl/fragment.glsl
index 1a8b1ef8..7361df71 100644
--- a/libweston/renderer-gl/fragment.glsl
+++ b/libweston/renderer-gl/fragment.glsl
@@ -127,14 +127,17 @@ uniform sampler2D tex2;
 uniform float view_alpha;
 uniform vec4 unicolor;
 
+#define MAX_CURVE_PARAMS 10
+#define MAX_CURVESET_PARAMS (MAX_CURVE_PARAMS * 3)
+
 uniform HIGHPRECISION sampler2D color_pre_curve_lut_2d;
 uniform HIGHPRECISION vec2 color_pre_curve_lut_scale_offset;
-uniform HIGHPRECISION float color_pre_curve_params[30];
+uniform HIGHPRECISION float color_pre_curve_params[MAX_CURVESET_PARAMS];
 uniform bool color_pre_curve_clamped_input;
 
 uniform HIGHPRECISION sampler2D color_post_curve_lut_2d;
 uniform HIGHPRECISION vec2 color_post_curve_lut_scale_offset;
-uniform HIGHPRECISION float color_post_curve_params[30];
+uniform HIGHPRECISION float color_post_curve_params[MAX_CURVESET_PARAMS];
 uniform bool color_post_curve_clamped_input;
 
 #if DEF_COLOR_MAPPING == SHADER_COLOR_MAPPING_3DLUT
@@ -245,19 +248,22 @@ powlin(float x, float g, float a, float b, float c, float d)
 }
 
 float
-sample_color_pre_curve_linpow(float x, compile_const int color_channel)
+sample_linpow(float params[MAX_CURVESET_PARAMS], bool must_clamp,
+	      float x, compile_const int color_channel)
 {
 	float g, a, b, c, d;
 
-	/* For each color channel we have 10 parameters. The params are
-	 * linearized in an array of size 30, in RGB order. */
-	g = color_pre_curve_params[0 + (color_channel * 10)];
-	a = color_pre_curve_params[1 + (color_channel * 10)];
-	b = color_pre_curve_params[2 + (color_channel * 10)];
-	c = color_pre_curve_params[3 + (color_channel * 10)];
-	d = color_pre_curve_params[4 + (color_channel * 10)];
+	/*
+	 * For each color channel we have MAX_CURVE_PARAMS parameters.
+	 * The parameters for the three curves are stored in RGB order.
+	 */
+	g = params[0 + color_channel * MAX_CURVE_PARAMS];
+	a = params[1 + color_channel * MAX_CURVE_PARAMS];
+	b = params[2 + color_channel * MAX_CURVE_PARAMS];
+	c = params[3 + color_channel * MAX_CURVE_PARAMS];
+	d = params[4 + color_channel * MAX_CURVE_PARAMS];
 
-	if (color_pre_curve_clamped_input)
+	if (must_clamp)
 		x = clamp(x, 0.0, 1.0);
 
 	/* We use mirroring for negative input values. */
@@ -267,6 +273,15 @@ sample_color_pre_curve_linpow(float x, compile_const int color_channel)
 	return linpow(x, g, a, b, c, d);
 }
 
+vec3
+sample_linpow_vec3(float params[MAX_CURVESET_PARAMS], bool must_clamp,
+		   vec3 color)
+{
+	return vec3(sample_linpow(params, must_clamp, color.r, 0),
+		    sample_linpow(params, must_clamp, color.g, 1),
+		    sample_linpow(params, must_clamp, color.b, 2));
+}
+
 float
 sample_color_pre_curve_powlin(float x, compile_const int color_channel)
 {
@@ -291,29 +306,6 @@ sample_color_pre_curve_powlin(float x, compile_const int color_channel)
 }
 
 float
-sample_color_post_curve_linpow(float x, compile_const int color_channel)
-{
-	float g, a, b, c, d;
-
-	/* For each color channel we have 10 parameters. The params are
-	 * linearized in an array of size 30, in RGB order. */
-	g = color_post_curve_params[0 + (color_channel * 10)];
-	a = color_post_curve_params[1 + (color_channel * 10)];
-	b = color_post_curve_params[2 + (color_channel * 10)];
-	c = color_post_curve_params[3 + (color_channel * 10)];
-	d = color_post_curve_params[4 + (color_channel * 10)];
-
-	if (color_post_curve_clamped_input)
-		x = clamp(x, 0.0, 1.0);
-
-	/* We use mirroring for negative input values. */
-	if (x < 0.0)
-		return -linpow(-x, g, a, b, c, d);
-
-	return linpow(x, g, a, b, c, d);
-}
-
-float
 sample_color_post_curve_powlin(float x, compile_const int color_channel)
 {
 	float g, a, b, c, d;
@@ -348,10 +340,9 @@ color_pre_curve(vec3 color)
 				       color_pre_curve_lut_scale_offset,
 				       color);
 	} else if (c_color_pre_curve == SHADER_COLOR_CURVE_LINPOW) {
-		ret.r = sample_color_pre_curve_linpow(color.r, 0);
-		ret.g = sample_color_pre_curve_linpow(color.g, 1);
-		ret.b = sample_color_pre_curve_linpow(color.b, 2);
-		return ret;
+		return sample_linpow_vec3(color_pre_curve_params,
+					  color_pre_curve_clamped_input,
+					  color);
 	} else if (c_color_pre_curve == SHADER_COLOR_CURVE_POWLIN) {
 		ret.r = sample_color_pre_curve_powlin(color.r, 0);
 		ret.g = sample_color_pre_curve_powlin(color.g, 1);
@@ -399,10 +390,9 @@ color_post_curve(vec3 color)
 				       color_post_curve_lut_scale_offset,
 				       color);
 	} else if (c_color_post_curve == SHADER_COLOR_CURVE_LINPOW) {
-		ret.r = sample_color_post_curve_linpow(color.r, 0);
-		ret.g = sample_color_post_curve_linpow(color.g, 1);
-		ret.b = sample_color_post_curve_linpow(color.b, 2);
-		return ret;
+		return sample_linpow_vec3(color_post_curve_params,
+					  color_post_curve_clamped_input,
+					  color);
 	} else if (c_color_post_curve == SHADER_COLOR_CURVE_POWLIN) {
 		ret.r = sample_color_post_curve_powlin(color.r, 0);
 		ret.g = sample_color_post_curve_powlin(color.g, 1);