Kill the vertex shader system; it is too complicated to get it right until we have...
[movit] / colorspace_conversion_effect.cpp
index fe8119a..4f6bf61 100644 (file)
@@ -1,4 +1,19 @@
+#include <assert.h>
+
 #include "colorspace_conversion_effect.h"
+#include "util.h"
+
+// 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;
+double rec709_Y_R = 0.2126, rec709_Y_G = 0.7152, rec709_Y_B = 0.0722;
+
+// Color coordinates from Rec. 601. (Separate for 525- and 625-line systems.)
+double rec601_525_x_R = 0.630, rec601_525_x_G = 0.310, rec601_525_x_B = 0.155;
+double rec601_525_y_R = 0.340, rec601_525_y_G = 0.595, rec601_525_y_B = 0.070;
+double rec601_625_x_R = 0.640, rec601_625_x_G = 0.290, rec601_625_x_B = 0.150;
+double rec601_625_y_R = 0.330, rec601_625_y_G = 0.600, rec601_625_y_B = 0.060;
+double rec601_Y_R = 0.299, rec601_Y_G = 0.587, rec601_Y_B = 0.114;
 
 ColorSpaceConversionEffect::ColorSpaceConversionEffect()
        : source_space(COLORSPACE_sRGB),
@@ -7,3 +22,77 @@ ColorSpaceConversionEffect::ColorSpaceConversionEffect()
        register_int("source_space", (int *)&source_space);
        register_int("destination_space", (int *)&destination_space);
 }
+
+void get_xyz_matrix(ColorSpace space, Matrix3x3 m)
+{
+       double x_R, x_G, x_B;
+       double y_R, y_G, y_B;
+       double Y_R, Y_G, Y_B;
+
+       switch (space) {
+       case COLORSPACE_REC_709:  // And sRGB.
+               x_R = rec709_x_R; x_G = rec709_x_G; x_B = rec709_x_B;
+               y_R = rec709_y_R; y_G = rec709_y_G; y_B = rec709_y_B;
+               Y_R = rec709_Y_R; Y_G = rec709_Y_G; Y_B = rec709_Y_B;
+               break;
+       case COLORSPACE_REC_601_525:
+               x_R = rec601_525_x_R; x_G = rec601_525_x_G; x_B = rec601_525_x_B;
+               y_R = rec601_525_y_R; y_G = rec601_525_y_G; y_B = rec601_525_y_B;
+               Y_R = rec601_Y_R;     Y_G = rec601_Y_G;     Y_B = rec601_Y_B;
+               break;
+       case COLORSPACE_REC_601_625:
+               x_R = rec601_625_x_R; x_G = rec601_625_x_G; x_B = rec601_625_x_B;
+               y_R = rec601_625_y_R; y_G = rec601_625_y_G; y_B = rec601_625_y_B;
+               Y_R = rec601_Y_R;     Y_G = rec601_Y_G;     Y_B = rec601_Y_B;
+               break;
+       default:
+               assert(false);
+       }
+
+       // Convert xyY -> XYZ.
+       double X_R, X_G, X_B;
+       X_R = Y_R * x_R / y_R;
+       X_G = Y_G * x_G / y_G;
+       X_B = Y_B * x_B / y_B;
+       
+       double Z_R, Z_G, Z_B;
+       Z_R = Y_R * (1.0f - x_R - y_R) / y_R;
+       Z_G = Y_G * (1.0f - x_G - y_G) / y_G;
+       Z_B = Y_B * (1.0f - x_B - y_B) / 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;
+}
+
+std::string ColorSpaceConversionEffect::output_fragment_shader()
+{
+       // Create a matrix to convert from source space -> XYZ,
+       // another matrix to convert from XYZ -> destination space,
+       // and then concatenate the two.
+       //
+       // 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[3], m[6],
+               m[1], m[4], m[7],
+               m[2], m[5], m[8]);
+       return buf + read_file("colorspace_conversion_effect.frag");
+}