Factorize the code to compute sampling points for bilinear sampling into a shared...

[movit] / colorspace_conversion_effect.cpp

diff --git a/colorspace_conversion_effect.cpp b/colorspace_conversion_effect.cpp
index 2447292c90ba9f1ec168055f5350200dc355e64c..3f075d2b721141ef6c13428c24b93c854d4879f3 100644 (file)
--- a/colorspace_conversion_effect.cpp
+++ b/colorspace_conversion_effect.cpp
@@ -1,8 +1,12 @@
 #include <assert.h>
 
+#include <Eigen/LU>
+
 #include "colorspace_conversion_effect.h"
 #include "util.h"
 
+using namespace Eigen;
+
 // Color coordinates from Rec. 709; sRGB uses the same primaries.
 double rec709_x_R = 0.640,  rec709_x_G = 0.300,  rec709_x_B = 0.150;
 double rec709_y_R = 0.330,  rec709_y_G = 0.600,  rec709_y_B = 0.060;
@@ -16,7 +20,7 @@ double rec601_625_y_R = 0.330, rec601_625_y_G = 0.600, rec601_625_y_B = 0.060;
 // The D65 white point. Given in both Rec. 601 and 709.
 double d65_x = 0.3127, d65_y = 0.3290;
 
-ColorSpaceConversionEffect::ColorSpaceConversionEffect()
+ColorspaceConversionEffect::ColorspaceConversionEffect()
        : source_space(COLORSPACE_sRGB),
          destination_space(COLORSPACE_sRGB)
 {
@@ -24,13 +28,10 @@ ColorSpaceConversionEffect::ColorSpaceConversionEffect()
        register_int("destination_space", (int *)&destination_space);
 }
 
-void get_xyz_matrix(ColorSpace space, Matrix3x3 m)
+Matrix3d get_xyz_matrix(Colorspace space)
 {
        if (space == COLORSPACE_XYZ) {
-               m[0] = 1.0f; m[3] = 0.0f; m[6] = 0.0f;
-               m[1] = 0.0f; m[4] = 1.0f; m[7] = 0.0f;
-               m[2] = 0.0f; m[5] = 0.0f; m[8] = 1.0f;
-               return;
+               return Matrix3d::Identity();
        }
 
        double x_R, x_G, x_B;
@@ -60,9 +61,11 @@ void get_xyz_matrix(ColorSpace space, Matrix3x3 m)
 
        // Find the XYZ coordinates of D65 (white point for both Rec. 601 and 709),
        // normalized so that Y=1.
-       double d65_X = d65_x / d65_y;
-       double d65_Y = 1.0;
-       double d65_Z = (1.0 - d65_x - d65_y) / d65_y;
+       Vector3d d65_XYZ(
+               d65_x / d65_y,
+               1.0,
+               (1.0 - d65_x - d65_y) / d65_y
+       );
 
        // We have, for each primary (example is with red):
        //
@@ -91,37 +94,40 @@ void get_xyz_matrix(ColorSpace space, Matrix3x3 m)
        //
        // Which we can solve for (Y_R, Y_G, Y_B) by inverting a 3x3 matrix.
 
-       Matrix3x3 temp, inverted;
-       temp[0] = x_R / y_R;
-       temp[3] = x_G / y_G;
-       temp[6] = x_B / y_B;
+       Matrix3d temp;
+       temp(0,0) = x_R / y_R;
+       temp(0,1) = x_G / y_G;
+       temp(0,2) = x_B / y_B;
 
-       temp[1] = 1.0;
-       temp[4] = 1.0;
-       temp[7] = 1.0;
+       temp(1,0) = 1.0;
+       temp(1,1) = 1.0;
+       temp(1,2) = 1.0;
 
-       temp[2] = z_R / y_R;
-       temp[5] = z_G / y_G;
-       temp[8] = z_B / y_B;
+       temp(2,0) = z_R / y_R;
+       temp(2,1) = z_G / y_G;
+       temp(2,2) = z_B / y_B;
 
-       invert_3x3_matrix(temp, inverted);
-       float Y_R, Y_G, Y_B;
-       multiply_3x3_matrix_float3(inverted, d65_X, d65_Y, d65_Z, &Y_R, &Y_G, &Y_B);
+       Vector3d Y_RGB = temp.inverse() * d65_XYZ;
 
        // Now convert xyY -> XYZ.
-       double X_R = temp[0] * Y_R;
-       double Z_R = temp[2] * Y_R;
-       double X_G = temp[3] * Y_G;
-       double Z_G = temp[5] * Y_G;
-       double X_B = temp[6] * Y_B;
-       double Z_B = temp[8] * Y_B;
-
-       m[0] = X_R; m[3] = X_G; m[6] = X_B;
-       m[1] = Y_R; m[4] = Y_G; m[7] = Y_B;
-       m[2] = Z_R; m[5] = Z_G; m[8] = Z_B;
+       double X_R = temp(0,0) * Y_RGB[0];
+       double Z_R = temp(2,0) * Y_RGB[0];
+
+       double X_G = temp(0,1) * Y_RGB[1];
+       double Z_G = temp(2,1) * Y_RGB[1];
+
+       double X_B = temp(0,2) * Y_RGB[2];
+       double Z_B = temp(2,2) * Y_RGB[2];
+
+       Matrix3d m;
+       m(0,0) = X_R;      m(0,1) = X_G;      m(0,2) = X_B;
+       m(1,0) = Y_RGB[0]; m(1,1) = Y_RGB[1]; m(1,2) = Y_RGB[2];
+       m(2,0) = Z_R;      m(2,1) = Z_G;      m(2,2) = Z_B;
+
+       return m;
 }
 
-std::string ColorSpaceConversionEffect::output_fragment_shader()
+std::string ColorspaceConversionEffect::output_fragment_shader()
 {
        // Create a matrix to convert from source space -> XYZ,
        // another matrix to convert from XYZ -> destination space,
@@ -129,26 +135,10 @@ std::string ColorSpaceConversionEffect::output_fragment_shader()
        //
        // Since we right-multiply the RGB column vector, the matrix
        // concatenation order needs to be the opposite of the operation order.
-       Matrix3x3 m;
-
-       Matrix3x3 source_space_to_xyz;
-       Matrix3x3 destination_space_to_xyz;
-       Matrix3x3 xyz_to_destination_space;
-
-       get_xyz_matrix(source_space, source_space_to_xyz);
-       get_xyz_matrix(destination_space, destination_space_to_xyz);
-       invert_3x3_matrix(destination_space_to_xyz, xyz_to_destination_space);
-       
-       multiply_3x3_matrices(xyz_to_destination_space, source_space_to_xyz, m);
-
-       char buf[1024];
-       sprintf(buf,
-               "const mat3 PREFIX(conversion_matrix) = mat3(\n"
-               "    %.8f, %.8f, %.8f,\n"
-               "    %.8f, %.8f, %.8f,\n"
-               "    %.8f, %.8f, %.8f);\n\n",
-               m[0], m[1], m[2],
-               m[3], m[4], m[5],
-               m[6], m[7], m[8]);
-       return buf + read_file("colorspace_conversion_effect.frag");
+       Matrix3d source_space_to_xyz = get_xyz_matrix(source_space);
+       Matrix3d xyz_to_destination_space = get_xyz_matrix(destination_space).inverse();
+       Matrix3d m = xyz_to_destination_space * source_space_to_xyz;
+
+       return output_glsl_mat3("PREFIX(conversion_matrix)", m) +
+               read_file("colorspace_conversion_effect.frag");
 }