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Use R"()" syntax for glsl shader strings for better readability #4795

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Merged
lgritz merged 1 commit into from
Jun 6, 2025
Merged

Use R"()" syntax for glsl shader strings for better readability #4795

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251 changes: 131 additions & 120 deletions src/iv/ivgl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -191,17 +191,18 @@ const char*
IvGL::color_func_shader_text()
{
// clang-format off
return
"uniform float gain;\n"
"uniform float gamma;\n"
"\n"
"vec4 ColorFunc(vec4 C)\n"
"{\n"
" C.xyz *= gain;\n"
" float invgamma = 1.0/gamma;\n"
" C.xyz = pow (C.xyz, vec3 (invgamma, invgamma, invgamma));\n"
" return C;\n"
"}\n";
return R"(
uniform float gain;
uniform float gamma;

vec4 ColorFunc(vec4 C)
{
C.xyz *= gain;
float invgamma = 1.0/gamma;
C.xyz = pow (C.xyz, vec3 (invgamma, invgamma, invgamma));
return C;
}
)";
// clang-format on
}

Expand Down Expand Up @@ -235,13 +236,14 @@ IvGL::create_shaders(void)

if (!m_vertex_shader) {
// clang-format off
static const GLchar* vertex_source =
"varying vec2 vTexCoord;\n"
"void main ()\n"
"{\n"
" vTexCoord = gl_MultiTexCoord0.xy;\n"
" gl_Position = ftransform();\n"
"}\n";
static const GLchar* vertex_source = R"(
varying vec2 vTexCoord;
void main ()
{
vTexCoord = gl_MultiTexCoord0.xy;
gl_Position = ftransform();
}
)";
// clang-format on

m_vertex_shader = glCreateShader(GL_VERTEX_SHADER);
Expand All @@ -258,109 +260,118 @@ IvGL::create_shaders(void)
}

// clang-format off
static const GLchar* fragment_source =
"uniform sampler2D imgtex;\n"
"varying vec2 vTexCoord;\n"
"uniform int startchannel;\n"
"uniform int colormode;\n"
static const GLchar* fragment_source = R"(
uniform sampler2D imgtex;
varying vec2 vTexCoord;
uniform int startchannel;
uniform int colormode;
// Remember, if imgchannels == 2, second channel would be channel 4 (a).
"uniform int imgchannels;\n"
"uniform int pixelview;\n"
"uniform int linearinterp;\n"
"uniform int width;\n"
"uniform int height;\n"
"vec4 rgba_mode (vec4 C)\n"
"{\n"
" if (imgchannels <= 2) {\n"
" if (startchannel == 1)\n"
" return vec4(C.aaa, 1.0);\n"
" return C.rrra;\n"
" }\n"
" return C;\n"
"}\n"
"vec4 rgb_mode (vec4 C)\n"
"{\n"
" if (imgchannels <= 2) {\n"
" if (startchannel == 1)\n"
" return vec4(C.aaa, 1.0);\n"
" return vec4 (C.rrr, 1.0);\n"
" }\n"
" float C2[4];\n"
" C2[0]=C.x; C2[1]=C.y; C2[2]=C.z; C2[3]=C.w;\n"
" return vec4 (C2[startchannel], C2[startchannel+1], C2[startchannel+2], 1.0);\n"
"}\n"
"vec4 singlechannel_mode (vec4 C)\n"
"{\n"
" float C2[4];\n"
" C2[0]=C.x; C2[1]=C.y; C2[2]=C.z; C2[3]=C.w;\n"
" if (startchannel > imgchannels)\n"
" return vec4 (0.0,0.0,0.0,1.0);\n"
" return vec4 (C2[startchannel], C2[startchannel], C2[startchannel], 1.0);\n"
"}\n"
"vec4 luminance_mode (vec4 C)\n"
"{\n"
" if (imgchannels <= 2)\n"
" return vec4 (C.rrr, C.a);\n"
" float lum = dot (C.rgb, vec3(0.2126, 0.7152, 0.0722));\n"
" return vec4 (lum, lum, lum, C.a);\n"
"}\n"
"float heat_red(float x)\n"
"{\n"
" return clamp (mix(0.0, 1.0, (x-0.35)/(0.66-0.35)), 0.0, 1.0) -\n"
" clamp (mix(0.0, 0.5, (x-0.89)/(1.0-0.89)), 0.0, 1.0);\n"
"}\n"
"float heat_green(float x)\n"
"{\n"
" return clamp (mix(0.0, 1.0, (x-0.125)/(0.375-0.125)), 0.0, 1.0) -\n"
" clamp (mix(0.0, 1.0, (x-0.64)/(0.91-0.64)), 0.0, 1.0);\n"
"}\n"
"vec4 heatmap_mode (vec4 C)\n"
"{\n"
" float C2[4];\n"
" C2[0]=C.x; C2[1]=C.y; C2[2]=C.z; C2[3]=C.w;\n"
" return vec4(heat_red(C2[startchannel]),\n"
" heat_green(C2[startchannel]),\n"
" heat_red(1.0-C2[startchannel]),\n"
" 1.0);\n"
"}\n"
"void main ()\n"
"{\n"
" vec2 st = vTexCoord;\n"
" float black = 0.0;\n"
" if (pixelview != 0 || linearinterp == 0) {\n"
" vec2 wh = vec2(width,height);\n"
" vec2 onehalf = vec2(0.5,0.5);\n"
" vec2 st_res = st * wh /* + onehalf */ ;\n"
" vec2 st_pix = floor (st_res);\n"
" vec2 st_rem = st_res - st_pix;\n"
" st = (st_pix + onehalf) / wh;\n"
" if (pixelview != 0) {\n"
" if (st.x < 0.0 || st.x >= 1.0 || \n"
" st.y < 0.0 || st.y >= 1.0 || \n"
" st_rem.x < 0.05 || st_rem.x >= 0.95 || \n"
" st_rem.y < 0.05 || st_rem.y >= 0.95)\n"
" black = 1.0;\n"
" }\n"
" }\n"
" vec4 C = texture2D (imgtex, st);\n"
" C = mix (C, vec4(0.05,0.05,0.05,1.0), black);\n"
" if (startchannel < 0)\n"
" C = vec4(0.0,0.0,0.0,1.0);\n"
" else if (colormode == 0)\n" // RGBA
" C = rgba_mode (C);\n"
" else if (colormode == 1)\n" // RGB (i.e., ignore alpha).
" C = rgb_mode (C);\n"
" else if (colormode == 2)\n" // Single channel.
" C = singlechannel_mode (C);\n"
" else if (colormode == 3)\n" // Luminance.
" C = luminance_mode (C);\n"
" else if (colormode == 4)\n" // Heatmap.
" C = heatmap_mode (C);\n"
" if (pixelview != 0)\n"
" C.a = 1.0;\n"
" C = ColorFunc(C);\n"
" gl_FragColor = C;\n"
"}\n";
uniform int imgchannels;
uniform int pixelview;
uniform int linearinterp;
uniform int width;
uniform int height;

vec4 rgba_mode (vec4 C)
{
if (imgchannels <= 2) {
if (startchannel == 1)
return vec4(C.aaa, 1.0);
return C.rrra;
}
return C;
}

vec4 rgb_mode (vec4 C)
{
if (imgchannels <= 2) {
if (startchannel == 1)
return vec4(C.aaa, 1.0);
return vec4 (C.rrr, 1.0);
}
float C2[4];
C2[0]=C.x; C2[1]=C.y; C2[2]=C.z; C2[3]=C.w;
return vec4 (C2[startchannel], C2[startchannel+1], C2[startchannel+2], 1.0);
}

vec4 singlechannel_mode (vec4 C)
{
float C2[4];
C2[0]=C.x; C2[1]=C.y; C2[2]=C.z; C2[3]=C.w;
if (startchannel > imgchannels)
return vec4 (0.0,0.0,0.0,1.0);
return vec4 (C2[startchannel], C2[startchannel], C2[startchannel], 1.0);
}

vec4 luminance_mode (vec4 C)
{
if (imgchannels <= 2)
return vec4 (C.rrr, C.a);
float lum = dot (C.rgb, vec3(0.2126, 0.7152, 0.0722));
return vec4 (lum, lum, lum, C.a);
}

float heat_red(float x)
{
return clamp (mix(0.0, 1.0, (x-0.35)/(0.66-0.35)), 0.0, 1.0) -
clamp (mix(0.0, 0.5, (x-0.89)/(1.0-0.89)), 0.0, 1.0);
}

float heat_green(float x)
{
return clamp (mix(0.0, 1.0, (x-0.125)/(0.375-0.125)), 0.0, 1.0) -
clamp (mix(0.0, 1.0, (x-0.64)/(0.91-0.64)), 0.0, 1.0);
}

vec4 heatmap_mode (vec4 C)
{
float C2[4];
C2[0]=C.x; C2[1]=C.y; C2[2]=C.z; C2[3]=C.w;
return vec4(heat_red(C2[startchannel]),
heat_green(C2[startchannel]),
heat_red(1.0-C2[startchannel]),
1.0);
}

void main ()
{
vec2 st = vTexCoord;
float black = 0.0;
if (pixelview != 0 || linearinterp == 0) {
vec2 wh = vec2(width,height);
vec2 onehalf = vec2(0.5,0.5);
vec2 st_res = st * wh /* + onehalf */ ;
vec2 st_pix = floor (st_res);
vec2 st_rem = st_res - st_pix;
st = (st_pix + onehalf) / wh;
if (pixelview != 0) {
if (st.x < 0.0 || st.x >= 1.0 ||
st.y < 0.0 || st.y >= 1.0 ||
st_rem.x < 0.05 || st_rem.x >= 0.95 ||
st_rem.y < 0.05 || st_rem.y >= 0.95)
black = 1.0;
}
}
vec4 C = texture2D (imgtex, st);
C = mix (C, vec4(0.05,0.05,0.05,1.0), black);
if (startchannel < 0)
C = vec4(0.0,0.0,0.0,1.0);
else if (colormode == 0) // RGBA
C = rgba_mode (C);
else if (colormode == 1) // RGB (i.e., ignore alpha).
C = rgb_mode (C);
else if (colormode == 2) // Single channel.
C = singlechannel_mode (C);
else if (colormode == 3) // Luminance.
C = luminance_mode (C);
else if (colormode == 4) // Heatmap.
C = heatmap_mode (C);
if (pixelview != 0)
C.a = 1.0;
C = ColorFunc(C);
gl_FragColor = C;
}
)";
// clang-format on

const char* fragment_sources[] = { "#version 120\n", color_shader,
Expand Down
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