build: hacer Vulkan SDK opcional usando SPIR-V pre-compilados

Si glslc no está disponible, CMake usa los headers en shaders/precompiled/
en lugar de fallar. Los SPIR-V son portátiles entre Windows y Linux, por
lo que el build funciona sin instalar Vulkan SDK.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CMakeLists.txt

@@ -28,42 +28,43 @@ endif()
 if(NOT APPLE)
     find_program(GLSLC glslc HINTS "$ENV{VULKAN_SDK}/bin" "$ENV{VULKAN_SDK}/Bin")
     if(NOT GLSLC)
-        message(FATAL_ERROR "glslc not found. Install the Vulkan SDK and ensure glslc is on PATH.")
+        message(STATUS "glslc not found — using precompiled SPIR-V headers from shaders/precompiled/")
+        set(SHADER_GEN_DIR "${CMAKE_SOURCE_DIR}/shaders/precompiled")
+    else()
+        set(SHADER_SRC_DIR "${CMAKE_SOURCE_DIR}/shaders")
+        set(SHADER_GEN_DIR "${CMAKE_BINARY_DIR}/generated_shaders")
+        file(MAKE_DIRECTORY "${SHADER_GEN_DIR}")
+
+        set(SPIRV_HEADERS)
+        foreach(SHADER sprite_vert sprite_frag postfx_vert postfx_frag ball_vert)
+            if(SHADER MATCHES "_vert$")
+                set(STAGE_FLAG "-fshader-stage=vertex")
+            else()
+                set(STAGE_FLAG "-fshader-stage=fragment")
+            endif()
+            string(REGEX REPLACE "_vert$" ".vert" GLSL_NAME "${SHADER}")
+            string(REGEX REPLACE "_frag$" ".frag" GLSL_NAME "${GLSL_NAME}")
+
+            set(GLSL_FILE "${SHADER_SRC_DIR}/${GLSL_NAME}")
+            set(SPV_FILE  "${SHADER_GEN_DIR}/${SHADER}.spv")
+            set(H_FILE    "${SHADER_GEN_DIR}/${SHADER}_spv.h")
+
+            add_custom_command(
+                OUTPUT "${H_FILE}"
+                COMMAND "${GLSLC}" ${STAGE_FLAG} -o "${SPV_FILE}" "${GLSL_FILE}"
+                COMMAND "${CMAKE_COMMAND}"
+                        -DINPUT="${SPV_FILE}"
+                        -DOUTPUT="${H_FILE}"
+                        -DVAR_NAME="k${SHADER}_spv"
+                        -P "${CMAKE_SOURCE_DIR}/cmake/spv_to_header.cmake"
+                DEPENDS "${GLSL_FILE}"
+                COMMENT "Compiling ${GLSL_NAME} to SPIRV"
+            )
+            list(APPEND SPIRV_HEADERS "${H_FILE}")
+        endforeach()
+
+        add_custom_target(shaders ALL DEPENDS ${SPIRV_HEADERS})
     endif()
-
-    set(SHADER_SRC_DIR "${CMAKE_SOURCE_DIR}/shaders")
-    set(SHADER_GEN_DIR "${CMAKE_BINARY_DIR}/generated_shaders")
-    file(MAKE_DIRECTORY "${SHADER_GEN_DIR}")
-
-    set(SPIRV_HEADERS)
-    foreach(SHADER sprite_vert sprite_frag postfx_vert postfx_frag ball_vert)
-        if(SHADER MATCHES "_vert$")
-            set(STAGE_FLAG "-fshader-stage=vertex")
-        else()
-            set(STAGE_FLAG "-fshader-stage=fragment")
-        endif()
-        string(REGEX REPLACE "_vert$" ".vert" GLSL_NAME "${SHADER}")
-        string(REGEX REPLACE "_frag$" ".frag" GLSL_NAME "${GLSL_NAME}")
-
-        set(GLSL_FILE "${SHADER_SRC_DIR}/${GLSL_NAME}")
-        set(SPV_FILE  "${SHADER_GEN_DIR}/${SHADER}.spv")
-        set(H_FILE    "${SHADER_GEN_DIR}/${SHADER}_spv.h")
-
-        add_custom_command(
-            OUTPUT "${H_FILE}"
-            COMMAND "${GLSLC}" ${STAGE_FLAG} -o "${SPV_FILE}" "${GLSL_FILE}"
-            COMMAND "${CMAKE_COMMAND}"
-                    -DINPUT="${SPV_FILE}"
-                    -DOUTPUT="${H_FILE}"
-                    -DVAR_NAME="k${SHADER}_spv"
-                    -P "${CMAKE_SOURCE_DIR}/cmake/spv_to_header.cmake"
-            DEPENDS "${GLSL_FILE}"
-            COMMENT "Compiling ${GLSL_NAME} to SPIRV"
-        )
-        list(APPEND SPIRV_HEADERS "${H_FILE}")
-    endforeach()
-
-    add_custom_target(shaders ALL DEPENDS ${SPIRV_HEADERS})
 endif()
 
 # Archivos fuente (excluir main_old.cpp)
@@ -103,7 +104,9 @@ set_target_properties(${PROJECT_NAME} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAK
 target_link_libraries(${PROJECT_NAME} ${LINK_LIBS})
 
 if(NOT APPLE)
-    add_dependencies(${PROJECT_NAME} shaders)
+    if(GLSLC)
+        add_dependencies(${PROJECT_NAME} shaders)
+    endif()
     target_include_directories(${PROJECT_NAME} PRIVATE "${SHADER_GEN_DIR}")
 endif()