c++ - Error compiling fragment shader on GLSL 1.30 -

what wrong following fragment shader? compiles ok under glsl 4.0 fails on glsl 1.30.

this code:

// fragment shader "uniform sampler2d texture;\n" "uniform sampler1d cmap;\n" "uniform float minz;\n" "uniform float maxz;\n" "\n" "void main() {\n" "    float height = texture2d(texture,gl_texcoord[0].st);\n" "    float lum = (height-minz)/(maxz-minz);\n" "    if (lum > 1.0) lum = 1.0;\n" "    else if (lum < 0.0) lum = 0.0;\n" "    gl_fragcolor = texture1d(cmap, lum);\n" "}" 

these errors:

fragment glcompileshader "" failed fragment shader "" infolog: 0:7(2): error: initializer of type vec4 cannot assigned variable of type float 0:8(2): error: initializer of type vec4 cannot assigned variable of type float 0:9(6): error: operands relational operators must scalar , numeric 0:9(6): error: if-statement condition must scalar boolean 0:9(17): error: value of type float cannot assigned variable of type vec4 0:10(11): error: operands relational operators must scalar , numeric 

well, error messages clear wrong:

0:7(2): error: initializer of type vec4 cannot assigned variable of type float ---- float height = texture2d(texture,gl_texcoord[0].st); 

one cannot assign vec4 float. texture2d returns vec4, cannot assigned float height. solution: add swizzle operator when need 1 channel:

float height = texture2d(texture,gl_texcoord[0].st).r; 

beside this, shader should not compile in glsl version > 140, since gl_texcoord removed in 150. same goes texture2d , texture1d method got replaced texture function in 150. specifying glsl version #version 400?