nv2a: Add SDL-based offscreen GL context interface

hw/xbox/nv2a/gl/gloffscreen_sdl.c

@@ -0,0 +1,104 @@
+/*
+ *  Offscreen OpenGL abstraction layer -- SDL based
+ *
+ *  Copyright (c) 2018 Matt Borgerson
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+#include "gloffscreen.h"
+
+#include <SDL.h>
+#include <SDL_syswm.h>
+
+struct _GloContext {
+    SDL_Window    *window;
+    SDL_GLContext gl_context;
+};
+
+/* Create an OpenGL context */
+GloContext *glo_context_create(void)
+{
+    fprintf(stderr, "%s\n", __func__);
+
+    GloContext *context = (GloContext *)malloc(sizeof(GloContext));
+    assert(context != NULL);
+
+    SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
+    SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
+    SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
+    SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
+    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
+    SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
+
+    // Initialize rendering context
+    SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+    SDL_GL_SetAttribute(
+        SDL_GL_CONTEXT_PROFILE_MASK,
+        SDL_GL_CONTEXT_PROFILE_CORE);
+
+    // Create main window
+    context->window = SDL_CreateWindow(
+        "SDL Offscreen Window",
+        SDL_WINDOWPOS_CENTERED,
+        SDL_WINDOWPOS_CENTERED,
+        640, 480,
+        SDL_WINDOW_OPENGL | SDL_WINDOW_HIDDEN);
+    if (context->window == NULL) {
+        fprintf(stderr, "%s: Failed to create window\n", __func__);
+        SDL_Quit();
+        exit(1);
+    }
+
+    context->gl_context = SDL_GL_CreateContext(context->window);
+    if (context->gl_context == NULL) {
+        fprintf(stderr, "%s: Failed to create GL context\n", __func__);
+        SDL_DestroyWindow(context->window);
+        SDL_Quit();
+        exit(1);
+    }
+
+    glo_set_current(context);
+
+    return context;
+}
+
+/* Set current context */
+void glo_set_current(GloContext *context)
+{
+    if (context == NULL) {
+        SDL_GL_MakeCurrent(NULL, NULL);
+    } else {
+        SDL_GL_MakeCurrent(context->window, context->gl_context);
+    }
+}
+
+/* Destroy a previously created OpenGL context */
+void glo_context_destroy(GloContext *context)
+{
+    if (!context) return;
+    glo_set_current(NULL);
+    free(context);
+}