Create empty texture idea, change function scopes

Some functions which should not be exposed in the API have been switched
to INTERNAL scope. We have a notion of an empty texture in World Traveller
that we can pass in situations where we just want to render a solid
colour with no associated texture.

The alternative to this was creating a separate shader for rendering
primitives but would require at some point to expose the AssetManager to
the renderer or the user on behalf has to manually switch shaders before
rendering (non-intuitive).

src/AssetManager.c

@@ -63,8 +63,8 @@ const i32 asset_loadTextureImage(AssetManager *assetManager,
 		return -1;
 	}
 
-	Texture tex = genTexture(CAST(GLuint)(imgWidth), CAST(GLuint)(imgHeight),
-	                         CAST(GLint)(bytesPerPixel), image);
+	Texture tex = texture_gen(CAST(GLuint)(imgWidth), CAST(GLuint)(imgHeight),
+	                          CAST(GLint)(bytesPerPixel), image);
 	glCheckError();
 	stbi_image_free(image);
 
@@ -111,6 +111,30 @@ INTERNAL GLuint createShaderFromPath(const char *const path, GLuint shadertype)
 	return result;
 }
 
+INTERNAL i32 shaderLoadProgram(Shader *const shader, const GLuint vertexShader,
+                               const GLuint fragmentShader)
+{
+	shader->id = glCreateProgram();
+	glAttachShader(shader->id, vertexShader);
+	glAttachShader(shader->id, fragmentShader);
+	glLinkProgram(shader->id);
+
+	glDeleteShader(fragmentShader);
+	glDeleteShader(vertexShader);
+
+	GLint success;
+	GLchar infoLog[512];
+	glGetProgramiv(shader->id, GL_LINK_STATUS, &success);
+	if (!success)
+	{
+		glGetProgramInfoLog(shader->id, 512, NULL, infoLog);
+		printf("glLinkProgram failed: %s\n", infoLog);
+		return -1;
+	}
+
+	return 0;
+}
+
 const i32 asset_loadShaderFiles(AssetManager *assetManager,
                                 const char *const vertexPath,
                                 const char *const fragmentPath,
@@ -121,7 +145,7 @@ const i32 asset_loadShaderFiles(AssetManager *assetManager,
 	    createShaderFromPath(fragmentPath, GL_FRAGMENT_SHADER);
 
 	Shader shader;
-	i32 result = shader_loadProgram(&shader, vertexShader, fragmentShader);
+	i32 result = shaderLoadProgram(&shader, vertexShader, fragmentShader);
 	if (result)
 		return result;
 
@@ -295,13 +319,13 @@ const i32 asset_loadTTFont(AssetManager *assetManager, const char *filePath)
 				    V2(CAST(f32)(glyphIndex * font->maxSize.w), CAST(f32) row);
 #if 1
 				fontAtlas->texRect[atlasIndex++] =
-				    getRect(origin, V2(CAST(f32) font->maxSize.w,
-				                       CAST(f32) font->maxSize.h));
+				    math_getRect(origin, V2(CAST(f32) font->maxSize.w,
+				                            CAST(f32) font->maxSize.h));
 #else
 				v2i fontSize =
 				    font->charMetrics[activeGlyph.codepoint - 32].trueSize;
-				fontAtlas->texRect[atlasIndex++] =
-				    getRect(origin, V2(CAST(f32)fontSize.x, CAST(f32)fontSize.y));
+				fontAtlas->texRect[atlasIndex++] = math_getRect(
+				    origin, V2(CAST(f32) fontSize.x, CAST(f32) fontSize.y));
 #endif
 			}
 
@@ -348,8 +372,8 @@ const i32 asset_loadTTFont(AssetManager *assetManager, const char *filePath)
 		}
 	}
 
-	Texture tex = genTexture(MAX_TEXTURE_SIZE, MAX_TEXTURE_SIZE, 4,
-	                         CAST(u8 *)fontBitmap);
+	Texture tex = texture_gen(MAX_TEXTURE_SIZE, MAX_TEXTURE_SIZE, 4,
+	                          CAST(u8 *) fontBitmap);
 	assetManager->textures[texlist_font] = tex;
 
 #ifdef WT_RENDER_FONT_FILE