1 static const char *sdr_src =

2 "uniform sampler2D tex;\n"

3 "uniform float aspect, scale;\n"

4 "uniform float lens_center_offset;\n"

5 "uniform vec4 dist_factors;\n"

6 "\n"

7 "vec2 distort_texcoords(in vec2 tc);\n"

8 "float barrel_scale(float x, in vec4 k);\n"

9 "\n"

10 "void main()\n"

11 "{\n"

12 " vec2 tc = distort_texcoords(gl_TexCoord[0].xy);\n"

13 "\n"

14 " float vis = any(greaterThan(tc, vec2(1.0)) || lessThan(tc, vec2(0.0))) ? 0.0 : 1.0;\n"

15 "\n"

16 " gl_FragColor.rgb = texture2D(tex, tc).rgb * vis;\n"

17 " gl_FragColor.a = 1.0;\n"

18 "}\n"

19 "\n"

20 "vec2 distort_texcoords(in vec2 tc)\n"

21 "{\n"

22 " // map tc [0, 1] -> [-1, 1]\n"

23 " vec2 pt = tc * 2.0 - 1.0;\n"

24 "\n"

25 " pt.x += lens_center_offset * 2.0;\n"

26 " pt.y /= aspect; // correct for aspect ratio\n"

27 "\n"

28 " float rad = barrel_scale(dot(pt, pt), dist_factors);\n"

29 " pt *= rad; // scale the point by the computer distortion radius\n"

30 "\n"

31 " pt /= scale;\n"

32 " pt.y *= aspect;\n"

33 " pt.x -= lens_center_offset * 2.0;\n"

34 "\n"

35 " // map back to range [0, 1]\n"

36 " return pt * 0.5 + 0.5;\n"

37 "}\n"

38 "\n"

39 "float barrel_scale(float rad, in vec4 k)\n"

40 "{\n"

41 " float radsq = rad * rad;\n"

42 " float radquad = radsq * radsq;\n"

43 " return k.x + k.y * radsq + k.z * radquad + k.w * radquad * radsq;\n"

44 "}\n";

45