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 "ui/shader.h"
  29
  30 #include "shader/texture-blit-vert.h"
  31 #include "shader/texture-blit-flip-vert.h"
  32 #include "shader/texture-blit-frag.h"
  33
  34 struct QemuGLShader {
  35     GLint texture_blit_prog;
  36     GLint texture_blit_flip_prog;
  37     GLint texture_blit_vao;
  38 };
  39
  40 /* ---------------------------------------------------------------------- */
  41
  42 static GLuint qemu_gl_init_texture_blit(GLint texture_blit_prog)
  43 {
  44     static const GLfloat in_position[] = {
  45         -1, -1,
  46         1,  -1,
  47         -1,  1,
  48         1,   1,
  49     };
  50     GLint l_position;
  51     GLuint vao, buffer;
  52
  53     glGenVertexArrays(1, &vao);
  54     glBindVertexArray(vao);
  55
  56     /* this is the VBO that holds the vertex data */
  57     glGenBuffers(1, &buffer);
  58     glBindBuffer(GL_ARRAY_BUFFER, buffer);
  59     glBufferData(GL_ARRAY_BUFFER, sizeof(in_position), in_position,
  60                  GL_STATIC_DRAW);
  61
  62     l_position = glGetAttribLocation(texture_blit_prog, "in_position");
  63     glVertexAttribPointer(l_position, 2, GL_FLOAT, GL_FALSE, 0, 0);
  64     glEnableVertexAttribArray(l_position);
  65
  66     glBindBuffer(GL_ARRAY_BUFFER, 0);
  67     glBindVertexArray(0);
  68
  69     return vao;
  70 }
  71
  72 void qemu_gl_run_texture_blit(QemuGLShader *gls, bool flip)
  73 {
  74     glUseProgram(flip
  75                  ? gls->texture_blit_flip_prog
  76                  : gls->texture_blit_prog);
  77     glBindVertexArray(gls->texture_blit_vao);
  78     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
  79 }
  80
  81 /* ---------------------------------------------------------------------- */
  82
  83 static GLuint qemu_gl_create_compile_shader(GLenum type, const GLchar *src)
  84 {
  85     GLuint shader;
  86     GLint status, length;
  87     char *errmsg;
  88
  89     shader = glCreateShader(type);
  90     glShaderSource(shader, 1, &src, 0);
  91     glCompileShader(shader);
  92
  93     glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
  94     if (!status) {
  95         glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
  96         errmsg = g_malloc(length);
  97         glGetShaderInfoLog(shader, length, &length, errmsg);
  98         fprintf(stderr, "%s: compile %s error\n%s\n", __func__,
  99                 (type == GL_VERTEX_SHADER) ? "vertex" : "fragment",
 100                 errmsg);
 101         g_free(errmsg);
 102         return 0;
 103     }
 104     return shader;
 105 }
 106
 107 static GLuint qemu_gl_create_link_program(GLuint vert, GLuint frag)
 108 {
 109     GLuint program;
 110     GLint status, length;
 111     char *errmsg;
 112
 113     program = glCreateProgram();
 114     glAttachShader(program, vert);
 115     glAttachShader(program, frag);
 116     glLinkProgram(program);
 117
 118     glGetProgramiv(program, GL_LINK_STATUS, &status);
 119     if (!status) {
 120         glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);
 121         errmsg = g_malloc(length);
 122         glGetProgramInfoLog(program, length, &length, errmsg);
 123         fprintf(stderr, "%s: link program: %s\n", __func__, errmsg);
 124         g_free(errmsg);
 125         return 0;
 126     }
 127     return program;
 128 }
 129
 130 static GLuint qemu_gl_create_compile_link_program(const GLchar *vert_src,
 131                                                   const GLchar *frag_src)
 132 {
 133     GLuint vert_shader, frag_shader, program;
 134
 135     vert_shader = qemu_gl_create_compile_shader(GL_VERTEX_SHADER, vert_src);
 136     frag_shader = qemu_gl_create_compile_shader(GL_FRAGMENT_SHADER, frag_src);
 137     if (!vert_shader || !frag_shader) {
 138         return 0;
 139     }
 140
 141     program = qemu_gl_create_link_program(vert_shader, frag_shader);
 142     glDeleteShader(vert_shader);
 143     glDeleteShader(frag_shader);
 144
 145     return program;
 146 }
 147
 148 /* ---------------------------------------------------------------------- */
 149
 150 QemuGLShader *qemu_gl_init_shader(void)
 151 {
 152     QemuGLShader *gls = g_new0(QemuGLShader, 1);
 153
 154     gls->texture_blit_prog = qemu_gl_create_compile_link_program
 155         (texture_blit_vert_src, texture_blit_frag_src);
 156     gls->texture_blit_flip_prog = qemu_gl_create_compile_link_program
 157         (texture_blit_flip_vert_src, texture_blit_frag_src);
 158     if (!gls->texture_blit_prog || !gls->texture_blit_flip_prog) {
 159         exit(1);
 160     }
 161
 162     gls->texture_blit_vao =
 163         qemu_gl_init_texture_blit(gls->texture_blit_prog);
 164
 165     return gls;
 166 }
 167
 168 void qemu_gl_fini_shader(QemuGLShader *gls)
 169 {
 170     if (!gls) {
 171         return;
 172     }
 173     g_free(gls);
 174 }