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Add offscreen rendering example
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@ -11,6 +11,10 @@ if (MSVC)
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add_definitions(-D_CRT_SECURE_NO_WARNINGS)
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endif()
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if (GLFW_USE_OSMESA)
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add_definitions(-DUSE_NATIVE_OSMESA)
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endif()
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include_directories("${GLFW_SOURCE_DIR}/deps")
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if (WIN32)
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@ -31,6 +35,7 @@ set(TINYCTHREAD "${GLFW_SOURCE_DIR}/deps/tinycthread.h"
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add_executable(boing WIN32 MACOSX_BUNDLE boing.c ${ICON} ${GLAD})
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add_executable(gears WIN32 MACOSX_BUNDLE gears.c ${ICON} ${GLAD})
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add_executable(heightmap WIN32 MACOSX_BUNDLE heightmap.c ${ICON} ${GLAD})
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add_executable(offscreen offscreen.c ${ICON} ${GLAD})
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add_executable(particles WIN32 MACOSX_BUNDLE particles.c ${ICON} ${TINYCTHREAD} ${GETOPT} ${GLAD})
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add_executable(simple WIN32 MACOSX_BUNDLE simple.c ${ICON} ${GLAD})
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add_executable(splitview WIN32 MACOSX_BUNDLE splitview.c ${ICON} ${GLAD})
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171
examples/offscreen.c
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171
examples/offscreen.c
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@ -0,0 +1,171 @@
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//========================================================================
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// Offscreen rendering example
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// Copyright (c) Camilla Berglund <elmindreda@glfw.org>
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//
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// This software is provided 'as-is', without any express or implied
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// warranty. In no event will the authors be held liable for any damages
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// arising from the use of this software.
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//
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// Permission is granted to anyone to use this software for any purpose,
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// including commercial applications, and to alter it and redistribute it
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// freely, subject to the following restrictions:
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//
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// 1. The origin of this software must not be misrepresented; you must not
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// claim that you wrote the original software. If you use this software
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// in a product, an acknowledgment in the product documentation would
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// be appreciated but is not required.
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//
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// 2. Altered source versions must be plainly marked as such, and must not
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// be misrepresented as being the original software.
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//
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// 3. This notice may not be removed or altered from any source
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// distribution.
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//
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//========================================================================
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#include <glad/glad.h>
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#include <GLFW/glfw3.h>
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#if USE_NATIVE_OSMESA
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#define GLFW_EXPOSE_NATIVE_OSMESA
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#include <GLFW/glfw3native.h>
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#endif
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#include "linmath.h"
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#include <stdlib.h>
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#include <stdio.h>
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#define STB_IMAGE_WRITE_IMPLEMENTATION
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#include <stb_image_write.h>
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static const struct
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{
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float x, y;
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float r, g, b;
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} vertices[3] =
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{
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{ -0.6f, -0.4f, 1.f, 0.f, 0.f },
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{ 0.6f, -0.4f, 0.f, 1.f, 0.f },
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{ 0.f, 0.6f, 0.f, 0.f, 1.f }
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};
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static const char* vertex_shader_text =
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"uniform mat4 MVP;\n"
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"attribute vec3 vCol;\n"
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"attribute vec2 vPos;\n"
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"varying vec3 color;\n"
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"void main()\n"
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"{\n"
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" gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
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" color = vCol;\n"
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"}\n";
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static const char* fragment_shader_text =
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"varying vec3 color;\n"
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"void main()\n"
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"{\n"
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" gl_FragColor = vec4(color, 1.0);\n"
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"}\n";
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static void error_callback(int error, const char* description)
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{
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fprintf(stderr, "Error: %s\n", description);
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}
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int main(void)
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{
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GLFWwindow* window;
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GLuint vertex_buffer, vertex_shader, fragment_shader, program;
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GLint mvp_location, vpos_location, vcol_location;
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float ratio;
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int width, height;
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mat4x4 mvp;
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char* buffer;
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glfwSetErrorCallback(error_callback);
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if (!glfwInit())
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exit(EXIT_FAILURE);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
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glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
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window = glfwCreateWindow(640, 480, "Simple example", NULL, NULL);
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if (!window)
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{
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glfwTerminate();
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exit(EXIT_FAILURE);
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}
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glfwMakeContextCurrent(window);
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gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);
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// NOTE: OpenGL error checks have been omitted for brevity
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glGenBuffers(1, &vertex_buffer);
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glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
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glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
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vertex_shader = glCreateShader(GL_VERTEX_SHADER);
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glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
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glCompileShader(vertex_shader);
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fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
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glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
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glCompileShader(fragment_shader);
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program = glCreateProgram();
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glAttachShader(program, vertex_shader);
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glAttachShader(program, fragment_shader);
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glLinkProgram(program);
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mvp_location = glGetUniformLocation(program, "MVP");
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vpos_location = glGetAttribLocation(program, "vPos");
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vcol_location = glGetAttribLocation(program, "vCol");
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glEnableVertexAttribArray(vpos_location);
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glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
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sizeof(vertices[0]), (void*) 0);
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glEnableVertexAttribArray(vcol_location);
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glVertexAttribPointer(vcol_location, 3, GL_FLOAT, GL_FALSE,
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sizeof(vertices[0]), (void*) (sizeof(float) * 2));
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glfwGetFramebufferSize(window, &width, &height);
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ratio = width / (float) height;
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glViewport(0, 0, width, height);
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glClear(GL_COLOR_BUFFER_BIT);
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mat4x4_ortho(mvp, -ratio, ratio, -1.f, 1.f, 1.f, -1.f);
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glUseProgram(program);
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glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
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glDrawArrays(GL_TRIANGLES, 0, 3);
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#if USE_NATIVE_OSMESA
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glfwGetOSMesaColorBuffer(window, &width, &height, NULL, (void**) &buffer);
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#else
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buffer = calloc(4, width * height);
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glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
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#endif
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// Write image Y-flipped because OpenGL
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stbi_write_png("offscreen.png",
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width, height, 4,
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buffer + (width * 4 * (height - 1)),
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-width * 4);
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#if USE_NATIVE_OSMESA
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// Here is where there's nothing
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#else
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free(buffer);
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#endif
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glfwDestroyWindow(window);
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glfwTerminate();
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exit(EXIT_SUCCESS);
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}
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