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042bb43b37
- cpp/functions/gfx: gl_shader, gl_framebuffer, fullscreen_quad, shader_canvas - cpp/apps/shaders_lab: main + 3 seed shaders (plasma, circle, checker) - ImGui docking layout: Code | Canvas | Controls Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
67 lines
2.0 KiB
Markdown
67 lines
2.0 KiB
Markdown
---
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name: gl_shader
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kind: function
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lang: cpp
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domain: gfx
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version: "1.0.0"
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purity: impure
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signature: "CompileResult compile_fragment(const std::string& user_fragment_src)"
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description: "Compila un cuerpo de fragment shader GLSL 330 y retorna un GL program listo para usar. Prepende automáticamente version, out vec4 fragColor y uniforms u_resolution/u_time/u_mouse. Usa GL_GLEXT_PROTOTYPES + GL/glext.h."
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tags: [opengl, shader, glsl, compile, fragment, gfx]
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uses_functions: []
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uses_types: []
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returns: []
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returns_optional: false
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error_type: "error_go_core"
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imports: [GL/gl.h, GL/glext.h]
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tested: false
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tests: []
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test_file_path: ""
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file_path: "cpp/functions/gfx/gl_shader.cpp"
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framework: opengl
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params:
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- name: user_fragment_src
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desc: "Cuerpo del fragment shader GLSL sin #version, sin 'out vec4 fragColor' ni declaraciones de uniforms. Solo el void main() y funciones auxiliares."
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output: "CompileResult con program=GL id si ok=true, o err_msg/err_line si falla. program=0 indica error."
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---
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# gl_shader
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Compila y enlaza un fragment shader GLSL 330 contra un vertex shader fijo que genera un fullscreen quad via `gl_VertexID`.
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## Vertex shader fijo
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```glsl
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#version 330 core
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const vec2 verts[6] = vec2[](
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vec2(-1,-1), vec2(1,-1), vec2(-1,1),
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vec2(1,-1), vec2(1,1), vec2(-1,1)
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);
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void main() { gl_Position = vec4(verts[gl_VertexID], 0.0, 1.0); }
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```
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## Preamble prepended al fragment
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```glsl
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#version 330 core
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out vec4 fragColor;
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uniform vec2 u_resolution;
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uniform float u_time;
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uniform vec2 u_mouse;
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```
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## Ejemplo
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```cpp
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auto r = fn::gfx::compile_fragment("void main() { fragColor = vec4(1,0,0,1); }");
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if (r.ok) {
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glUseProgram(r.program);
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} else {
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fprintf(stderr, "line %d: %s\n", r.err_line, r.err_msg.c_str());
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}
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```
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## Notas
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Usa `#define GL_GLEXT_PROTOTYPES` + `<GL/gl.h>` + `<GL/glext.h>` (mismo patrón que `graph_renderer`). El loader de ImGui ya ha inicializado los symbols GL antes de que esta función sea llamada. El err_line del fragment se ajusta restando las 4 líneas del preamble.
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