GLProgram: load and store uniform locations

src/GLProgram.cc

@@ -1,10 +1,6 @@
 #include "GLProgram.h"
 #include "GLShader.h"
-
-typedef struct
-{
-    GLuint id;
-} GLProgram;
+#include <string.h>
 
 static VALUE ruby_class;
 
@@ -92,6 +88,43 @@ static VALUE GLProgram_link(VALUE self)
     return Qnil;
 }
 
+static VALUE GLProgram_load_uniform_location(VALUE self, VALUE uniform)
+{
+    static const char * uniform_names[] = {
+        "viewport_size",
+        "position",
+        "size",
+        "texture",
+        "color",
+    };
+    GLProgram * glprogram;
+    Data_Get_Struct(self, GLProgram, glprogram);
+    uniform = rb_funcall(uniform, rb_intern("to_s"), 0);
+    const char * uniform_cstr = StringValueCStr(uniform);
+    int uniform_index = -1;
+    for (int i = 0;
+         i < (int)(sizeof(uniform_names) / sizeof(uniform_names[0]));
+         i++)
+    {
+        if (strcmp(uniform_cstr, uniform_names[i]) == 0)
+        {
+            uniform_index = i;
+            break;
+        }
+    }
+    if (uniform_index >= 0)
+    {
+        glprogram->uniforms[uniform_index] = glGetUniformLocation(glprogram->id, uniform_cstr);
+    }
+    else
+    {
+        rb_raise(rb_eRuntimeError,
+                 "Unknown uniform name '%s'",
+                 uniform_cstr);
+    }
+    return Qnil;
+}
+
 void GLProgram_Init()
 {
     ruby_class = rb_define_class("GLProgram", rb_cObject);
@@ -99,6 +132,7 @@ void GLProgram_Init()
     rb_define_method(ruby_class, "attach_shader", (VALUE(*)(...))GLProgram_attach_shader, 1);
     rb_define_method(ruby_class, "bind_attribute", (VALUE(*)(...))GLProgram_bind_attribute, 2);
     rb_define_method(ruby_class, "link", (VALUE(*)(...))GLProgram_link, 0);
+    rb_define_method(ruby_class, "load_uniform_location", (VALUE(*)(...))GLProgram_load_uniform_location, 1);
 }
 
 GLuint GLProgram_GetID(VALUE program)
@@ -107,21 +141,3 @@ GLuint GLProgram_GetID(VALUE program)
     Data_Get_Struct(program, GLProgram, glprogram);
     return glprogram->id;
 }
-
-#if 0
-GLint GLProgram::get_uniform(const std::string & uniform_name)
-{
-    if (m_id > 0u)
-    {
-        auto it = m_uniforms.find(uniform_name);
-        if (it != m_uniforms.end())
-        {
-            return it->second;
-        }
-        GLint loc = glGetUniformLocation(m_id, uniform_name.c_str());
-        m_uniforms[uniform_name] = loc;
-        return loc;
-    }
-    return -1;
-}
-#endif

src/GLProgram.h

@@ -3,6 +3,22 @@
 
 #include "ruby.h"
 #include "gl3w.h"
+#include <unordered_map>
+
+enum
+{
+    UNIFORM_VIEWPORT_SIZE,
+    UNIFORM_POSITION,
+    UNIFORM_SIZE,
+    UNIFORM_TEXTURE,
+    UNIFORM_COLOR,
+};
+
+struct GLProgram
+{
+    GLuint id;
+    std::unordered_map<int, GLuint> uniforms;
+};
 
 void GLProgram_Init();
 GLuint GLProgram_GetID(VALUE program);