ui/shader.c

   1 /*
   2  * QEMU opengl shader helper functions
   3  *
   4  * Copyright (c) 2014 Red Hat
   5  *
   6  * Authors:
   7  *    Gerd Hoffmann <kraxel@redhat.com>
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a copy
  10  * of this software and associated documentation files (the "Software"), to deal
  11  * in the Software without restriction, including without limitation the rights
  12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13  * copies of the Software, and to permit persons to whom the Software is
  14  * furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included in
  17  * all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  22  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  25  * THE SOFTWARE.
  26  */
  27 #include "qemu/osdep.h"
  28 #include "qemu-common.h"
  29 #include "ui/shader.h"
  30
  31 #include "shader/texture-blit-vert.h"
  32 #include "shader/texture-blit-flip-vert.h"
  33 #include "shader/texture-blit-frag.h"
  34
  35 struct QemuGLShader {
  36     GLint texture_blit_prog;
  37     GLint texture_blit_flip_prog;
  38     GLint texture_blit_vao;
  39 };
  40
  41 /* ---------------------------------------------------------------------- */
  42
  43 static GLuint qemu_gl_init_texture_blit(GLint texture_blit_prog)
  44 {
  45     static const GLfloat in_position[] = {
  46         -1, -1,
  47         1,  -1,
  48         -1,  1,
  49         1,   1,
  50     };
  51     GLint l_position;
  52     GLuint vao, buffer;
  53
  54     glGenVertexArrays(1, &vao);
  55     glBindVertexArray(vao);
  56
  57     /* this is the VBO that holds the vertex data */
  58     glGenBuffers(1, &buffer);
  59     glBindBuffer(GL_ARRAY_BUFFER, buffer);
  60     glBufferData(GL_ARRAY_BUFFER, sizeof(in_position), in_position,
  61                  GL_STATIC_DRAW);
  62
  63     l_position = glGetAttribLocation(texture_blit_prog, "in_position");
  64     glVertexAttribPointer(l_position, 2, GL_FLOAT, GL_FALSE, 0, 0);
  65     glEnableVertexAttribArray(l_position);
  66
  67     glBindBuffer(GL_ARRAY_BUFFER, 0);
  68     glBindVertexArray(0);
  69
  70     return vao;
  71 }
  72
  73 void qemu_gl_run_texture_blit(QemuGLShader *gls, bool flip)
  74 {
  75     glUseProgram(flip
  76                  ? gls->texture_blit_flip_prog
  77                  : gls->texture_blit_prog);
  78     glBindVertexArray(gls->texture_blit_vao);
  79     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
  80 }
  81
  82 /* ---------------------------------------------------------------------- */
  83
  84 static GLuint qemu_gl_create_compile_shader(GLenum type, const GLchar *src)
  85 {
  86     GLuint shader;
  87     GLint status, length;
  88     char *errmsg;
  89
  90     shader = glCreateShader(type);
  91     glShaderSource(shader, 1, &src, 0);
  92     glCompileShader(shader);
  93
  94     glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
  95     if (!status) {
  96         glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
  97         errmsg = g_malloc(length);
  98         glGetShaderInfoLog(shader, length, &length, errmsg);
  99         fprintf(stderr, "%s: compile %s error\n%s\n", __func__,
 100                 (type == GL_VERTEX_SHADER) ? "vertex" : "fragment",
 101                 errmsg);
 102         g_free(errmsg);
 103         return 0;
 104     }
 105     return shader;
 106 }
 107
 108 static GLuint qemu_gl_create_link_program(GLuint vert, GLuint frag)
 109 {
 110     GLuint program;
 111     GLint status, length;
 112     char *errmsg;
 113
 114     program = glCreateProgram();
 115     glAttachShader(program, vert);
 116     glAttachShader(program, frag);
 117     glLinkProgram(program);
 118
 119     glGetProgramiv(program, GL_LINK_STATUS, &status);
 120     if (!status) {
 121         glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);
 122         errmsg = g_malloc(length);
 123         glGetProgramInfoLog(program, length, &length, errmsg);
 124         fprintf(stderr, "%s: link program: %s\n", __func__, errmsg);
 125         g_free(errmsg);
 126         return 0;
 127     }
 128     return program;
 129 }
 130
 131 static GLuint qemu_gl_create_compile_link_program(const GLchar *vert_src,
 132                                                   const GLchar *frag_src)
 133 {
 134     GLuint vert_shader, frag_shader, program;
 135
 136     vert_shader = qemu_gl_create_compile_shader(GL_VERTEX_SHADER, vert_src);
 137     frag_shader = qemu_gl_create_compile_shader(GL_FRAGMENT_SHADER, frag_src);
 138     if (!vert_shader || !frag_shader) {
 139         return 0;
 140     }
 141
 142     program = qemu_gl_create_link_program(vert_shader, frag_shader);
 143     glDeleteShader(vert_shader);
 144     glDeleteShader(frag_shader);
 145
 146     return program;
 147 }
 148
 149 /* ---------------------------------------------------------------------- */
 150
 151 QemuGLShader *qemu_gl_init_shader(void)
 152 {
 153     QemuGLShader *gls = g_new0(QemuGLShader, 1);
 154
 155     gls->texture_blit_prog = qemu_gl_create_compile_link_program
 156         (texture_blit_vert_src, texture_blit_frag_src);
 157     gls->texture_blit_flip_prog = qemu_gl_create_compile_link_program
 158         (texture_blit_flip_vert_src, texture_blit_frag_src);
 159     if (!gls->texture_blit_prog || !gls->texture_blit_flip_prog) {
 160         exit(1);
 161     }
 162
 163     gls->texture_blit_vao =
 164         qemu_gl_init_texture_blit(gls->texture_blit_prog);
 165
 166     return gls;
 167 }
 168
 169 void qemu_gl_fini_shader(QemuGLShader *gls)
 170 {
 171     if (!gls) {
 172         return;
 173     }
 174     g_free(gls);
 175 }