mesa: initial support for uniform variable initializers.

This lets one specify initial values for uniforms in the code, avoiding
the need to call glUniform() in some cases.

(cherry picked from commit 379ff8c9567940ebff44870cf7b0202882445fa6)

1 files changed, 22 insertions, 5 deletions

diff --git a/src/mesa/shader/slang/slang_codegen.c b/src/mesa/shader/slang/slang_codegen.c
index d83e3b01e6..a76b6da32b 100644
--- a/src/mesa/shader/slang/slang_codegen.c
+++ b/src/mesa/shader/slang/slang_codegen.c
@@ -3705,11 +3705,6 @@ _slang_codegen_global_variable(slang_assemble_ctx *A, slang_variable *var,
       const GLint totalSize = array_size(size, var->array_len);
       const GLuint swizzle = _slang_var_swizzle(totalSize, 0);
 
-      if (var->initializer) {
-         slang_info_log_error(A->log, "illegal initializer for uniform '%s'", varName);
-         return GL_FALSE;
-      }
-
       if (prog) {
          /* user-defined uniform */
          if (datatype == GL_NONE) {
@@ -3734,6 +3729,12 @@ _slang_codegen_global_variable(slang_assemble_ctx *A, slang_variable *var,
                 * "f.a"  (GL_FLOAT_VEC3)
                 * "f.b"  (GL_FLOAT_VEC4)
                 */
+
+               if (var->initializer) {
+                  slang_info_log_error(A->log,
+                     "unsupported initializer for uniform '%s'", varName);
+                  return GL_FALSE;
+               }
             }
             else {
                slang_info_log_error(A->log,
@@ -3747,6 +3748,22 @@ _slang_codegen_global_variable(slang_assemble_ctx *A, slang_variable *var,
                                                  totalSize, datatype);
             store = _slang_new_ir_storage_swz(PROGRAM_UNIFORM, uniformLoc,
                                               totalSize, swizzle);
+            if (var->initializer) {
+               _slang_simplify(var->initializer, &A->space, A->atoms);
+               if (var->initializer->type == SLANG_OPER_LITERAL_FLOAT ||
+                   var->initializer->type == SLANG_OPER_LITERAL_INT) {
+                  /* simple float/vector initializer */
+                  GLfloat *uniformValue =
+                     prog->Parameters->ParameterValues[uniformLoc];
+                  COPY_4V(uniformValue, var->initializer->literal);
+               }
+               else {
+                  /* complex initializer */
+                  slang_info_log_error(A->log,
+                     "unsupported initializer for uniform '%s'", varName);
+                  return GL_FALSE;
+               }
+            }
          }
       }
       else {