Java tutorial
/* * Copyright 2016 MovingBlocks * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.terasology.rendering.opengl; import org.lwjgl.BufferUtils; import org.lwjgl.opengl.GL11; import org.lwjgl.opengl.GL20; import java.nio.FloatBuffer; import java.nio.IntBuffer; import static org.lwjgl.opengl.EXTFramebufferObject.GL_COLOR_ATTACHMENT0_EXT; import static org.lwjgl.opengl.EXTFramebufferObject.GL_FRAMEBUFFER_EXT; import static org.lwjgl.opengl.EXTFramebufferObject.glBindFramebufferEXT; import static org.lwjgl.opengl.GL11.*; import static org.lwjgl.opengl.GL11.GL_MODELVIEW; import static org.lwjgl.opengl.GL11.glPopMatrix; public final class OpenGLUtils { private static int displayListQuad = -1; private OpenGLUtils() { // Utility class, no instance required } /** * Removes the rotation and scale part of the current OpenGL matrix. * Can be used to render billboards like particles. */ public static void applyBillboardOrientation() { // Fetch the current modelview matrix final FloatBuffer model = BufferUtils.createFloatBuffer(16); GL11.glGetFloat(GL11.GL_MODELVIEW_MATRIX, model); // And undo all rotations and scaling for (int i = 0; i < 3; i++) { for (int j = 0; j < 3; j++) { if (i == j) { model.put(i * 4 + j, 1.0f); } else { model.put(i * 4 + j, 0.0f); } } } GL11.glLoadMatrix(model); } /** * Sets the viewport of the currently bound FBO to the dimensions of the FBO * given as parameter. * * @param fbo The FBO whose dimensions will be matched by the viewport of the currently bound FBO. */ public static void setViewportToSizeOf(FBO fbo) { glViewport(0, 0, fbo.width(), fbo.height()); } public static void setViewportToSizeOf(DefaultDynamicFBOs defaultDynamicFBO) { glViewport(0, 0, defaultDynamicFBO.width(), defaultDynamicFBO.height()); } /** * Unbinds any currently bound FBO and binds the default Frame Buffer, * which is usually the Display (be it the full screen or a window). */ public static void bindDisplay() { glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0); } /** * Once an FBO is bound, opengl commands will act on it, i.e. by drawing on it. * Meanwhile shaders might output not just colors but additional per-pixel data. This method establishes on which * of an FBOs attachments, subsequent opengl commands and shaders will draw on. * * @param fbo The FBO holding the attachments to be set or unset for drawing. * @param color If True the color buffer is set as drawable. If false subsequent commands and shaders won't be able to draw on it. * @param normal If True the normal buffer is set as drawable. If false subsequent commands and shaders won't be able to draw on it. * @param lightBuffer If True the light buffer is set as drawable. If false subsequent commands and shaders won't be able to draw on it. */ // TODO: verify if this can become part of the FBO.bind() method. public static void setRenderBufferMask(FBO fbo, boolean color, boolean normal, boolean lightBuffer) { if (fbo == null) { return; } int attachmentId = 0; IntBuffer bufferIds = BufferUtils.createIntBuffer(3); if (fbo.colorBufferTextureId != 0) { if (color) { bufferIds.put(GL_COLOR_ATTACHMENT0_EXT + attachmentId); } attachmentId++; } if (fbo.normalsBufferTextureId != 0) { if (normal) { bufferIds.put(GL_COLOR_ATTACHMENT0_EXT + attachmentId); } attachmentId++; } if (fbo.lightBufferTextureId != 0 && lightBuffer) { bufferIds.put(GL_COLOR_ATTACHMENT0_EXT + attachmentId); } bufferIds.flip(); GL20.glDrawBuffers(bufferIds); } /** * Renders a quad filling the whole currently set viewport. */ public static void renderFullscreenQuad() { glMatrixMode(GL_MODELVIEW); glPushMatrix(); glLoadIdentity(); glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity(); renderQuad(); glPopMatrix(); glMatrixMode(GL_MODELVIEW); glPopMatrix(); } /** * First sets a viewport and then renders a quad filling it. * * @param x an integer representing the x coordinate (in pixels) of the origin of the viewport. * @param y an integer representing the y coordinate (in pixels) of the origin of the viewport. * @param viewportWidth an integer representing the width (in pixels) the viewport. * @param viewportHeight an integer representing the height (in pixels) the viewport. */ // TODO: perhaps remove this method and make sure the viewport is set explicitly. // TODO: find a much more suitable name for this method public static void renderFullscreenQuad(int x, int y, int viewportWidth, int viewportHeight) { glViewport(x, y, viewportWidth, viewportHeight); renderFullscreenQuad(); } // TODO: replace with a proper resident buffer with interleaved vertex and uv coordinates private static void renderQuad() { if (displayListQuad == -1) { displayListQuad = glGenLists(1); glNewList(displayListQuad, GL11.GL_COMPILE); glBegin(GL_QUADS); glColor4f(1.0f, 1.0f, 1.0f, 1.0f); glTexCoord2d(0.0, 0.0); glVertex3i(-1, -1, -1); glTexCoord2d(1.0, 0.0); glVertex3i(1, -1, -1); glTexCoord2d(1.0, 1.0); glVertex3i(1, 1, -1); glTexCoord2d(0.0, 1.0); glVertex3i(-1, 1, -1); glEnd(); glEndList(); } glCallList(displayListQuad); } }