* Helpful OpenGL resources:
*
* https://www.seas.upenn.edu/~pcozzi/OpenGLInsights/OpenGLInsights-AsynchronousBufferTransfers.pdf
* https://learnopengl.com/Advanced-OpenGL/Advanced-Data
* https://gamedev.stackexchange.com/questions/91995/edit-vbo-data-or-create-a-new-one
*
* @author James Seibel
* @version 10-23-2021
*/
public class GlProxy
{
private static GlProxy instance = null;
private static MinecraftWrapper mc = MinecraftWrapper.INSTANCE;
/** Minecraft's GLFW window */
public final long minecraftGlContext;
/** Minecraft's GL context */
public final GLCapabilities minecraftGlCapabilities;
/** the LodBuilder's GLFW window */
public final long lodBuilderGlContext;
/** the LodBuilder's GL context */
public final GLCapabilities lodBuilderGlCapabilities;
/**
* This is just used for debugging, hopefully it can be removed once
* the context switching is more stable.
*/
public Thread lodBuilderOwnerThread = null;
/** Does this computer's GPU support fancy fog? */
public final boolean fancyFogAvailable;
/** Requires OpenGL 4.5, and offers the best buffer uploading */
public final boolean bufferStorageSupported;
/** Requires OpenGL 3.0 */
public final boolean mapBufferRangeSupported;
private GlProxy()
{
ClientProxy.LOGGER.error("Creating " + GlProxy.class.getSimpleName() + "... If this is the last message you see in the log there must have been a OpenGL error.");
// getting Minecraft's context has to be done on the render thread,
// where the GL context is
if (!RenderSystem.isOnRenderThread())
throw new IllegalStateException(GlProxy.class.getSimpleName() + " was created outside the render thread!");
//============================//
// create the builder context //
//============================//
// get Minecraft's context
minecraftGlContext = GLFW.glfwGetCurrentContext();
minecraftGlCapabilities = GL.getCapabilities();
// create the LodBuilder's context
// Hopefully this shouldn't cause any issues with other mods that need custom contexts
// (although the number that do should be relatively few)
GLFW.glfwWindowHint(GLFW.GLFW_VISIBLE, GLFW.GLFW_FALSE);
// create an invisible window to hold the context
lodBuilderGlContext = GLFW.glfwCreateWindow(640, 480, "LOD window", 0L, minecraftGlContext);
GLFW.glfwMakeContextCurrent(lodBuilderGlContext);
lodBuilderGlCapabilities = GL.createCapabilities();
// Since this is called on the render thread, make sure the Minecraft context is used in the end
GLFW.glfwMakeContextCurrent(minecraftGlContext);
GL.setCapabilities(minecraftGlCapabilities);
//==============================//
// determine the OpenGL version //
//==============================//
bufferStorageSupported = minecraftGlCapabilities.OpenGL45;
mapBufferRangeSupported = minecraftGlCapabilities.OpenGL30;
if (!minecraftGlCapabilities.OpenGL15)
{
String errorMessage = ModInfo.READABLE_NAME + " was initializing " + GlProxy.class.getSimpleName() + " and discoverd this GPU doesn't support OpenGL 1.5 or greater.";
mc.crashMinecraft(errorMessage + " Sorry I couldn't tell you sooner :(", new UnsupportedOperationException("This GPU doesn't support OpenGL 1.5 or greater."));
}
if (!bufferStorageSupported)
{
String fallBackVersion = mapBufferRangeSupported ? "3.0" : "1.5";
ClientProxy.LOGGER.error("This GPU doesn't support OpenGL 4.5, falling back to OpenGL " + fallBackVersion + ". This may cause stuttering and reduced performance.");
}
//==================================//
// get any GPU related capabilities //
//==================================//
// see if this GPU can run fancy fog
fancyFogAvailable = GL.getCapabilities().GL_NV_fog_distance;
if (!fancyFogAvailable)
ClientProxy.LOGGER.info("This GPU does not support GL_NV_fog_distance. This means that the fancy fog option will not be available.");
// GlProxy creation success
ClientProxy.LOGGER.error(GlProxy.class.getSimpleName() + " creation successful. OpenGL smiles upon you this day.");
}
/**
* A wrapper function to make switching contexts easier.
* Does nothing if the calling thread is already using newContext.
*/
public void setGlContext(GlProxyContext newContext)
{
GlProxyContext currentContext = getGlContext();
// we don't have to change the context, we're already there.
if (currentContext == newContext)
return;
long contextPointer = 0L;
GLCapabilities newGlCapabilities = null;
// get the pointer(s) for this context
switch (newContext)
{
case LOD_BUILDER:
contextPointer = lodBuilderGlContext;
newGlCapabilities = lodBuilderGlCapabilities;
break;
case MINECRAFT:
contextPointer = minecraftGlContext;
newGlCapabilities = minecraftGlCapabilities;
break;
default: // default should never happen, it is just here to make the compiler happy
case NONE:
// 0L is equivalent to null
break;
}
GLFW.glfwMakeContextCurrent(contextPointer);
GL.setCapabilities(newGlCapabilities);
// used for debugging
if (newContext == GlProxyContext.LOD_BUILDER)
lodBuilderOwnerThread = Thread.currentThread();
else if (newContext == GlProxyContext.NONE && currentContext == GlProxyContext.LOD_BUILDER)
lodBuilderOwnerThread = null;
}
/** Returns this thread's OpenGL context. */
public GlProxyContext getGlContext()
{
long currentContext = GLFW.glfwGetCurrentContext();
if (currentContext == lodBuilderGlContext)
return GlProxyContext.LOD_BUILDER;
else if (currentContext == minecraftGlContext)
return GlProxyContext.MINECRAFT;
else if (currentContext == 0L)
return GlProxyContext.NONE;
else
// hopefully this shouldn't happen, but
// at least now we will be notified if it does happen
throw new IllegalStateException(Thread.currentThread().getName() + " has a unknown OpenGl context: [" + currentContext + "]. Minecraft context [" + minecraftGlContext + "], LodBuilder context [" + lodBuilderGlContext + "], no context [0].");
}
public static GlProxy getInstance()
{
if (instance == null)
instance = new GlProxy();
return instance;
}
}