掌機 - Miyoo Flip - C/C++ - DRM/KMS - OpenGL ES 2.0 - Draw 2 Triangles



參考資訊:
https://gist.github.com/dvdhrm/5083553
https://www.kernel.org/doc/html/v4.15/gpu/drm-kms.html
https://github.com/grate-driver/libdrm/blob/master/xf86drmMode.h
https://gist.github.com/Miouyouyou/89e9fe56a2c59bce7d4a18a858f389ef

main.c

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <sys/mman.h>
#include <unistd.h>
#include <gbm.h>
#include <xf86drm.h>
#include <xf86drmMode.h>
#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>
#include <EGL/egl.h>
#include <EGL/eglext.h>
 
static int fd = -1;
static int fb = -1;
static int waiting_for_flip = 0;
 
static drmModeRes *res = NULL;
static drmModeCrtc *crtc = NULL;
static drmModeEncoder *enc = NULL;
static drmModeConnector *conn = NULL;
  
static void flip_handler(int fd, unsigned int frame, unsigned int sec, unsigned int usec, void *data)
{
    *((int *)data) = 0;
}
 
const char *vShaderSrc =
    "attribute vec4 vPosition;    \n"
    "void main(void)              \n"
    "{                            \n"
    "    const float angle = 90.0 * (3.1415 * 2.0) / 360.0;                                                                            \n"
    "    mat4 rot = mat4(cos(angle), -sin(angle), 0.0, 0.0, sin(angle), cos(angle), 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0); \n"
    "    gl_Position = vPosition * rot; \n"
    "}";
   
const char *fShaderSrc =
    "#ifdef GL_ES               \n"
    "precision mediump float;   \n"
    "#endif                     \n"
    "uniform vec4 vColor;       \n"
    "void main(void)            \n"
    "{                          \n"
    "    gl_FragColor = vColor; \n"
    "}";
 
drmEventContext evctx = {
    .version = DRM_EVENT_CONTEXT_VERSION,
    .page_flip_handler = flip_handler,
};
 
int main(int argc, char *argv[])
{
    const int w = 640;
    const int h = 480;
    const int bpp = 32;
    const int depth = 24;
  
    int i = 0;
    int j = 0;
  
    fd = open("/dev/dri/card0", O_RDWR | O_CLOEXEC);
    res = drmModeGetResources(fd);
    conn = drmModeGetConnector(fd, res->connectors[1]);
    enc = drmModeGetEncoder(fd, res->encoders[2]);
    crtc = drmModeGetCrtc(fd, res->crtcs[1]);
 
    struct gbm_device *gbm = gbm_create_device(fd);
    struct gbm_surface *gs = gbm_surface_create(gbm, crtc->mode.hdisplay, crtc->mode.vdisplay, GBM_FORMAT_XRGB8888, GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);
 
    EGLint egl_major = 0;
    EGLint egl_minor = 0;
    EGLint num_configs = 0;
    EGLConfig configs = {0};
    EGLDisplay display = EGL_NO_DISPLAY;
    EGLSurface surface = EGL_NO_SURFACE;
    EGLContext context = EGL_NO_CONTEXT;
    EGLint config_attribs[] = {
        EGL_SURFACE_TYPE,    EGL_WINDOW_BIT,
        EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
        EGL_RED_SIZE,   1, 
        EGL_GREEN_SIZE, 1,
        EGL_BLUE_SIZE,  1, 
        EGL_ALPHA_SIZE, 0,
        EGL_NONE
    };
    EGLint const context_attributes[] = {
        EGL_CONTEXT_CLIENT_VERSION, 2,
        EGL_NONE,
    };
    GLuint vShader = 0;
    GLuint fShader = 0;
    GLuint pObject = 0;
    GLint compiled = 0;
    GLfloat vVertices[] = {
         0.0f,  0.5f, 0.0f,
        -0.5f, -0.5f, 0.0f,
         0.5f, -0.5f, 0.0f
    };
 
    PFNEGLGETPLATFORMDISPLAYEXTPROC get_platform_display = NULL;
    get_platform_display = (void *)eglGetProcAddress("eglGetPlatformDisplayEXT");
    display = get_platform_display(EGL_PLATFORM_GBM_KHR, gbm, NULL);
    eglInitialize(display, &egl_major, &egl_minor);
    eglBindAPI(EGL_OPENGL_ES_API);
    eglChooseConfig(display, config_attribs, &configs, 1, &num_configs);
    surface = eglCreateWindowSurface(display, configs, gs, NULL);
    context = eglCreateContext(display, configs, EGL_NO_CONTEXT, context_attributes);
    eglMakeCurrent(display, surface, surface, context);
  
    vShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vShader, 1, &vShaderSrc, NULL);
    glCompileShader(vShader);
    glGetShaderiv(vShader, GL_COMPILE_STATUS, &compiled);
   
    fShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fShader, 1, &fShaderSrc, NULL);
    glCompileShader(fShader);
    glGetShaderiv(fShader, GL_COMPILE_STATUS, &compiled);
    
    pObject = glCreateProgram();
    glAttachShader(pObject, vShader);
    glAttachShader(pObject, fShader);
    glLinkProgram(pObject);
    glUseProgram(pObject);
   
    glViewport(0, 0, w, h);
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
  
    GLuint vp = glGetAttribLocation(pObject, "vPosition");
    GLuint vc = glGetUniformLocation(pObject, "vColor");
  
    glViewport(0, 0, w, h);
    glClear(GL_COLOR_BUFFER_BIT);
  
    vVertices[0] = 0.0;
    vVertices[1] = 1.0;
    vVertices[2] = 0.0;
    vVertices[3] = -1.0;
    vVertices[4] = 0.0;
    vVertices[5] = 0.0;
    vVertices[6] = 0.0;
    vVertices[7] = 0.0;
    vVertices[8] = 0.0;
    glVertexAttribPointer(vp, 3, GL_FLOAT, GL_FALSE, 0, vVertices);
    glEnableVertexAttribArray(vp);
    glUniform4f(vc, 1.0f, 0.0f, 0.0f, 1.0f);
    glDrawArrays(GL_TRIANGLES, 0, 3);
  
    vVertices[0] = 0.0;
    vVertices[1] = 0.0;
    vVertices[2] = 0.0;
    vVertices[3] = 0.0;
    vVertices[4] = -1.0;
    vVertices[5] = 0.0;
    vVertices[6] = 1.0;
    vVertices[7] = -1.0;
    vVertices[8] = 0.0;
    glVertexAttribPointer(vp, 3, GL_FLOAT, GL_FALSE, 0, vVertices);
    glUniform4f(vc, 0.0f, 1.0f, 0.0f, 1.0f);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    eglSwapBuffers(display, surface);
 
    struct gbm_bo *bo = gbm_surface_lock_front_buffer(gs);
    drmModeAddFB(fd, w, h, depth, bpp, gbm_bo_get_stride(bo), gbm_bo_get_handle(bo).u32, &fb);
    drmModeSetCrtc(fd, crtc->crtc_id, fb, 0, 0, (uint32_t *)conn, 1, &crtc->mode);
 
    waiting_for_flip = 1;
    drmModePageFlip(fd, crtc->crtc_id, fb, DRM_MODE_PAGE_FLIP_EVENT, (void *)&waiting_for_flip);
    while (waiting_for_flip) {
        drmHandleEvent(fd, &evctx);
    }
    gbm_surface_release_buffer(gs, bo);
    sleep(3);
 
    eglMakeCurrent(display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
    eglDestroyContext(display, context);
    eglDestroySurface(display, surface);
 
    drmModeRmFB(fd, fb);
    drmModeFreeCrtc(crtc);
    drmModeFreeEncoder(enc);
    drmModeFreeConnector(conn);
    drmModeFreeResources(res);
    close(fd);
    return 0;
}

編譯、執行

$ /opt/flip/bin/aarch64-linux-gcc main.c -O3 -o main -I/opt/flip/aarch64-flip-linux-gnu/sysroot/usr/include/libdrm -ldrm -lEGL -lGLESv2 -lgbm

root@rk3566-buildroot:/mnt/SDCARD# ./main