Java tutorial
/* * Copyright LWJGL. All rights reserved. * License terms: https://www.lwjgl.org/license */ package org.lwjgl.demo.stb; import org.lwjgl.glfw.*; import org.lwjgl.opengl.*; import org.lwjgl.system.*; import java.io.*; import java.nio.*; import java.util.*; import static java.lang.Math.*; import static org.lwjgl.demo.glfw.GLFWUtil.*; import static org.lwjgl.demo.util.IOUtil.*; import static org.lwjgl.glfw.Callbacks.*; import static org.lwjgl.glfw.GLFW.*; import static org.lwjgl.opengl.GL11.*; import static org.lwjgl.opengl.GL12.*; import static org.lwjgl.stb.STBImage.*; import static org.lwjgl.stb.STBImageResize.*; import static org.lwjgl.system.MemoryStack.*; import static org.lwjgl.system.MemoryUtil.*; /** STB Image demo. */ public final class Image { private final ByteBuffer image; private final int w; private final int h; private final int comp; private long window; private int ww; private int wh; private boolean ctrlDown; private int scale; private Callback debugProc; private Image(String imagePath) { ByteBuffer imageBuffer; try { imageBuffer = ioResourceToByteBuffer(imagePath, 8 * 1024); } catch (IOException e) { throw new RuntimeException(e); } try (MemoryStack stack = stackPush()) { IntBuffer w = stack.mallocInt(1); IntBuffer h = stack.mallocInt(1); IntBuffer comp = stack.mallocInt(1); // Use info to read image metadata without decoding the entire image. // We don't need this for this demo, just testing the API. if (!stbi_info_from_memory(imageBuffer, w, h, comp)) { throw new RuntimeException("Failed to read image information: " + stbi_failure_reason()); } else { System.out.println("OK with reason: " + stbi_failure_reason()); } System.out.println("Image width: " + w.get(0)); System.out.println("Image height: " + h.get(0)); System.out.println("Image components: " + comp.get(0)); System.out.println("Image HDR: " + stbi_is_hdr_from_memory(imageBuffer)); // Decode the image image = stbi_load_from_memory(imageBuffer, w, h, comp, 0); if (image == null) { throw new RuntimeException("Failed to load image: " + stbi_failure_reason()); } this.w = w.get(0); this.h = h.get(0); this.comp = comp.get(0); } } public static void main(String[] args) { String imagePath; if (args.length == 0) { System.out.println( "Use 'ant demo -Dclass=org.lwjgl.demo.stb.Image -Dargs=<path>' to load a different image.\n"); imagePath = "lwjgl32.png"; } else { imagePath = args[0]; } new Image(imagePath).run(); } private void run() { try { init(); loop(); } finally { try { destroy(); } catch (Exception e) { e.printStackTrace(); } } } private void windowSizeChanged(long window, int width, int height) { this.ww = width; this.wh = height; glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0.0, width, height, 0.0, -1.0, 1.0); glMatrixMode(GL_MODELVIEW); } private static void framebufferSizeChanged(long window, int width, int height) { glViewport(0, 0, width, height); } private void init() { GLFWErrorCallback.createPrint().set(); if (!glfwInit()) { throw new IllegalStateException("Unable to initialize GLFW"); } glfwDefaultWindowHints(); glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE); glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1); GLFWVidMode vidmode = Objects.requireNonNull(glfwGetVideoMode(glfwGetPrimaryMonitor())); ww = max(800, min(w, vidmode.width() - 160)); wh = max(600, min(h, vidmode.height() - 120)); this.window = glfwCreateWindow(ww, wh, "STB Image Demo", NULL, NULL); if (window == NULL) { throw new RuntimeException("Failed to create the GLFW window"); } // Center window glfwSetWindowPos(window, (vidmode.width() - ww) / 2, (vidmode.height() - wh) / 2); glfwSetWindowRefreshCallback(window, window -> render()); glfwSetWindowSizeCallback(window, this::windowSizeChanged); glfwSetFramebufferSizeCallback(window, Image::framebufferSizeChanged); glfwSetKeyCallback(window, (window, key, scancode, action, mods) -> { ctrlDown = (mods & GLFW_MOD_CONTROL) != 0; if (action == GLFW_RELEASE) { return; } switch (key) { case GLFW_KEY_ESCAPE: glfwSetWindowShouldClose(window, true); break; case GLFW_KEY_KP_ADD: case GLFW_KEY_EQUAL: setScale(scale + 1); break; case GLFW_KEY_KP_SUBTRACT: case GLFW_KEY_MINUS: setScale(scale - 1); break; case GLFW_KEY_0: case GLFW_KEY_KP_0: if (ctrlDown) { setScale(0); } break; } }); glfwSetScrollCallback(window, (window, xoffset, yoffset) -> { if (ctrlDown) { setScale(scale + (int) yoffset); } }); // Create context glfwMakeContextCurrent(window); GL.createCapabilities(); debugProc = GLUtil.setupDebugMessageCallback(); glfwSwapInterval(1); glfwShowWindow(window); glfwInvoke(window, this::windowSizeChanged, Image::framebufferSizeChanged); } private void setScale(int scale) { this.scale = max(-9, scale); } private void premultiplyAlpha() { int stride = w * 4; for (int y = 0; y < h; y++) { for (int x = 0; x < w; x++) { int i = y * stride + x * 4; float alpha = (image.get(i + 3) & 0xFF) / 255.0f; image.put(i + 0, (byte) round(((image.get(i + 0) & 0xFF) * alpha))); image.put(i + 1, (byte) round(((image.get(i + 1) & 0xFF) * alpha))); image.put(i + 2, (byte) round(((image.get(i + 2) & 0xFF) * alpha))); } } } private int createTexture() { int texID = glGenTextures(); glBindTexture(GL_TEXTURE_2D, texID); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); int format; if (comp == 3) { if ((w & 3) != 0) { glPixelStorei(GL_UNPACK_ALIGNMENT, 2 - (w & 1)); } format = GL_RGB; } else { premultiplyAlpha(); glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA); format = GL_RGBA; } glTexImage2D(GL_TEXTURE_2D, 0, format, w, h, 0, format, GL_UNSIGNED_BYTE, image); ByteBuffer input_pixels = image; int input_w = w; int input_h = h; int mipmapLevel = 0; while (1 < input_w || 1 < input_h) { int output_w = Math.max(1, input_w >> 1); int output_h = Math.max(1, input_h >> 1); ByteBuffer output_pixels = memAlloc(output_w * output_h * comp); stbir_resize_uint8_generic(input_pixels, input_w, input_h, input_w * comp, output_pixels, output_w, output_h, output_w * comp, comp, comp == 4 ? 3 : STBIR_ALPHA_CHANNEL_NONE, STBIR_FLAG_ALPHA_PREMULTIPLIED, STBIR_EDGE_CLAMP, STBIR_FILTER_MITCHELL, STBIR_COLORSPACE_SRGB); if (mipmapLevel == 0) { stbi_image_free(image); } else { memFree(input_pixels); } glTexImage2D(GL_TEXTURE_2D, ++mipmapLevel, format, output_w, output_h, 0, format, GL_UNSIGNED_BYTE, output_pixels); input_pixels = output_pixels; input_w = output_w; input_h = output_h; } if (mipmapLevel == 0) { stbi_image_free(image); } else { memFree(input_pixels); } return texID; } private void loop() { int texID = createTexture(); glEnable(GL_TEXTURE_2D); glClearColor(43f / 255f, 43f / 255f, 43f / 255f, 0f); while (!glfwWindowShouldClose(window)) { glfwPollEvents(); render(); } glDisable(GL_TEXTURE_2D); glDeleteTextures(texID); } private void render() { glClear(GL_COLOR_BUFFER_BIT); float scaleFactor = 1.0f + scale * 0.1f; glPushMatrix(); glTranslatef(ww * 0.5f, wh * 0.5f, 0.0f); glScalef(scaleFactor, scaleFactor, 1f); glTranslatef(-w * 0.5f, -h * 0.5f, 0.0f); glBegin(GL_QUADS); { glTexCoord2f(0.0f, 0.0f); glVertex2f(0.0f, 0.0f); glTexCoord2f(1.0f, 0.0f); glVertex2f(w, 0.0f); glTexCoord2f(1.0f, 1.0f); glVertex2f(w, h); glTexCoord2f(0.0f, 1.0f); glVertex2f(0.0f, h); } glEnd(); glPopMatrix(); glfwSwapBuffers(window); } private void destroy() { if (debugProc != null) { debugProc.free(); } glfwFreeCallbacks(window); glfwDestroyWindow(window); glfwTerminate(); Objects.requireNonNull(glfwSetErrorCallback(null)).free(); } }