8e55b9311d0fd64e74fc14bd4f46c6c8ed5114ba
[gltest.git] / glutil_gl2.cpp
1 /* gltest - small OpenGL tearing test program
2  * Copyright (C) 2012-2013 Ralf Jung <post@ralfj.de>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
17  */
18
19 #include "glutil.h"
20
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string>
24 #include <sstream>
25
26 // extension functions we use
27 typedef GLuint (*GLCREATESHADERPROC) (GLenum type);
28 typedef void (*GLGETSHADERIVPROC) (GLuint shader, GLenum pname, GLint *params);
29 typedef void (*GLGETSHADERINFOLOGPROC) (GLuint shader, GLsizei bufSize, GLsizei *length, GLchar *infoLog);
30 typedef void (*GLSHADERSOURCEPROC) (GLuint shader, GLsizei count, const GLchar* const *string, const GLint *length);
31 typedef void (*GLCOMPILESHADERPROC) (GLuint shader);
32 typedef GLuint (*GLCREATEPROGRAMPROC) (void);
33 typedef void (*GLATTACHSHADERPROC) (GLuint program, GLuint shader);
34 typedef void (*GLLINKPROGRAMPROC) (GLuint program);
35 typedef GLint (*GLGETATTRIBLOCATIONPROC) (GLuint program, const GLchar *name);
36 typedef void (*GLUSEPROGRAMPROC) (GLuint program);
37
38 typedef void (*GLVERTEXATTRIBPOINTERPROC) (GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *pointer);
39 typedef void (*GLENABLEVERTEXATTRIBARRAYPROC) (GLuint index);
40 typedef void (*GLGENBUFFERSPROC) (GLsizei n, GLuint *buffers);
41 typedef void (*GLBINDBUFFERPROC) (GLenum target, GLuint buffer);
42 typedef void (*GLBUFFERDATAPROC) (GLenum target, GLsizeiptr size, const GLvoid *data, GLenum usage);
43 typedef void (*GLDELETEBUFFERSPROC) (GLsizei n, const GLuint *buffers);
44
45 #ifdef CON_GL3
46 // VAOs are only supported in GL3+, and not needed in earler contexts
47 typedef void (*GLBINDVERTEXARRAYPROC) (GLuint array);
48 typedef void (*GLDELETEVERTEXARRAYSPROC) (GLsizei n, const GLuint *arrays);
49 typedef void (*GLGENVERTEXARRAYSPROC) (GLsizei n, GLuint *arrays);
50 #endif
51
52 GLGETSHADERIVPROC p_glGetShaderiv = NULL;
53 GLGETSHADERINFOLOGPROC p_glGetShaderInfoLog = NULL;
54 GLCREATESHADERPROC p_glCreateShader = NULL;
55 GLSHADERSOURCEPROC p_glShaderSource = NULL;
56 GLCOMPILESHADERPROC p_glCompileShader = NULL;
57 GLCREATEPROGRAMPROC p_glCreateProgram = NULL;
58 GLATTACHSHADERPROC p_glAttachShader = NULL;
59 GLLINKPROGRAMPROC p_glLinkProgram = NULL;
60 GLGETATTRIBLOCATIONPROC p_glGetAttribLocation = NULL;
61 GLUSEPROGRAMPROC p_glUseProgram = NULL;
62
63 GLVERTEXATTRIBPOINTERPROC p_glVertexAttribPointer = NULL;
64 GLENABLEVERTEXATTRIBARRAYPROC p_glEnableVertexAttribArray = NULL;
65 GLGENBUFFERSPROC p_glGenBuffers = NULL;
66 GLBINDBUFFERPROC p_glBindBuffer = NULL;
67 GLBUFFERDATAPROC p_glBufferData = NULL;
68 GLDELETEBUFFERSPROC p_glDeleteBuffers = NULL;
69
70 #ifdef CON_GL3
71 GLBINDVERTEXARRAYPROC p_glBindVertexArray = NULL;
72 GLDELETEVERTEXARRAYSPROC p_glDeleteVertexArrays = NULL;
73 GLGENVERTEXARRAYSPROC p_glGenVertexArrays = NULL;
74 #endif
75
76 // resolve function pointers
77 static T_proc resolveFunctionPointer(T_glGetProcAddress p_glGetProcAddress, const char *name)
78 {
79         T_proc proc = p_glGetProcAddress(name);
80         if (proc == NULL) {
81                 die("Error resolvung function %s\n", name);
82         }
83         return proc;
84 }
85
86 void resolveFunctionPointers(T_glGetProcAddress p_glGetProcAddress)
87 {
88 #ifdef CON_GL1
89         // we need to check if we have GL 2.0 or greater
90         std::string version = (char*)glGetString(GL_VERSION);
91         std::stringstream ssv(version);
92         std::string major;
93         std::getline(ssv, major, '.');
94         std::stringstream ssm(major);
95         int majorVersion;
96         ssm >> majorVersion;
97         if (majorVersion < 2) {
98                 die("Need at least GL 2.0 to function properly, but detected version %d\n", majorVersion);
99         }
100 #endif
101         
102         // now get the function pointers
103         p_glGetShaderiv = (GLGETSHADERIVPROC)resolveFunctionPointer(p_glGetProcAddress, "glGetShaderiv");
104         p_glGetShaderInfoLog = (GLGETSHADERINFOLOGPROC)resolveFunctionPointer(p_glGetProcAddress, "glGetShaderInfoLog");
105         p_glCreateShader = (GLCREATESHADERPROC)resolveFunctionPointer(p_glGetProcAddress, "glCreateShader");
106         p_glShaderSource = (GLSHADERSOURCEPROC)resolveFunctionPointer(p_glGetProcAddress, "glShaderSource");
107         p_glCompileShader = (GLCOMPILESHADERPROC)resolveFunctionPointer(p_glGetProcAddress, "glCompileShader");
108         p_glCreateProgram = (GLCREATEPROGRAMPROC)resolveFunctionPointer(p_glGetProcAddress, "glCreateProgram");
109         p_glAttachShader = (GLATTACHSHADERPROC)resolveFunctionPointer(p_glGetProcAddress, "glAttachShader");
110         p_glLinkProgram = (GLLINKPROGRAMPROC)resolveFunctionPointer(p_glGetProcAddress, "glLinkProgram");
111         p_glGetAttribLocation = (GLGETATTRIBLOCATIONPROC)resolveFunctionPointer(p_glGetProcAddress, "glGetAttribLocation");
112
113 #ifdef CON_GL3
114         p_glBindVertexArray = (GLBINDVERTEXARRAYPROC)resolveFunctionPointer(p_glGetProcAddress, "glBindVertexArray");
115         p_glDeleteVertexArrays = (GLDELETEVERTEXARRAYSPROC)resolveFunctionPointer(p_glGetProcAddress, "glDeleteVertexArrays");
116         p_glGenVertexArrays = (GLGENVERTEXARRAYSPROC)resolveFunctionPointer(p_glGetProcAddress, "glGenVertexArrays");
117 #endif
118
119         p_glUseProgram = (GLUSEPROGRAMPROC)resolveFunctionPointer(p_glGetProcAddress, "glUseProgram");
120         p_glVertexAttribPointer = (GLVERTEXATTRIBPOINTERPROC)resolveFunctionPointer(p_glGetProcAddress, "glVertexAttribPointer");
121         p_glEnableVertexAttribArray = (GLENABLEVERTEXATTRIBARRAYPROC)resolveFunctionPointer(p_glGetProcAddress, "glEnableVertexAttribArray");
122         p_glGenBuffers = (GLGENBUFFERSPROC)resolveFunctionPointer(p_glGetProcAddress, "glGenBuffers");
123         p_glBindBuffer = (GLBINDBUFFERPROC)resolveFunctionPointer(p_glGetProcAddress, "glBindBuffer");
124         p_glBufferData = (GLBUFFERDATAPROC)resolveFunctionPointer(p_glGetProcAddress, "glBufferData");
125         p_glDeleteBuffers = (GLDELETEBUFFERSPROC)resolveFunctionPointer(p_glGetProcAddress, "glDeleteBuffers");
126 }
127
128 // shaders
129 static const char *vertex_shader_source =
130 "#version 100 \n\
131 attribute vec2 position; \n\
132 attribute vec3 color; \n\
133 varying vec3 frag_color; \n\
134 void main() \n\
135 { \n\
136         frag_color = color; \n\
137         gl_Position = vec4(position * vec2(2) - vec2(1), 0.0, 1.0); \n\
138 }";
139 static const char *fragment_shader_source =
140 "#version 100 \n\
141 varying vec3 frag_color; \n\
142 void main(void) \n\
143 { \n\
144         gl_FragColor = vec4(frag_color, 1.0); \n\
145 }";
146
147
148 // OpenGL IDs (yeah, this is a bad hack... do we care?)
149 static GLuint program;
150 static struct {
151         GLint position;
152         GLint color;
153 } attributes;
154
155 // some local hlper functions
156 static void show_info_log(GLuint object)
157 {
158         GLint log_length;
159         p_glGetShaderiv(object, GL_INFO_LOG_LENGTH, &log_length);
160         char *log = new char[log_length];
161         p_glGetShaderInfoLog(object, log_length, NULL, log);
162         fprintf(stderr, "%s", log);
163         delete[] log;
164 }
165
166 static GLuint compile_shader(GLenum shader_type, const char *source)
167 {
168         GLuint shader = p_glCreateShader(shader_type);
169         p_glShaderSource(shader, 1, &source, NULL);
170         p_glCompileShader(shader);
171         GLint shader_ok;
172         p_glGetShaderiv(shader, GL_COMPILE_STATUS, &shader_ok);
173         if (!shader_ok) {
174                 fprintf(stderr, "Failed to compile shader\n");
175                 show_info_log(shader);
176                 exit(1);
177         }
178         checkGlError("Compiling shader");
179         return shader;
180 }
181
182 static GLuint createArrayBuffer(GLsizeiptr size, GLfloat *data)
183 {
184         GLuint buffer;
185         p_glGenBuffers(1, &buffer);
186         p_glBindBuffer(GL_ARRAY_BUFFER, buffer);
187         p_glBufferData(GL_ARRAY_BUFFER, size, data, GL_STATIC_DRAW);
188         checkGlError("Creating array buffer");
189         return buffer;
190 }
191
192 // initialisation
193 void initialise2dProjection()
194 {
195         GLuint vertex_shader = compile_shader(GL_VERTEX_SHADER, vertex_shader_source);
196         GLuint fragment_shader = compile_shader(GL_FRAGMENT_SHADER, fragment_shader_source);
197         program = p_glCreateProgram();
198         p_glAttachShader(program, vertex_shader);
199         p_glAttachShader(program, fragment_shader);
200         p_glLinkProgram(program);
201         attributes.position = p_glGetAttribLocation(program, "position");
202         attributes.color = p_glGetAttribLocation(program, "color");
203 }
204
205 // draw a quad
206 void drawQuad(GLfloat red, GLfloat green, GLfloat blue, GLfloat x1, GLfloat y1, GLfloat x2, GLfloat y2)
207 {
208         p_glUseProgram(program);
209         checkGlError("Enabling the shaders");
210
211 #ifdef CON_GL3
212         // create a vertex array obect and use it
213         GLuint vao;
214         p_glGenVertexArrays(1, &vao);
215         p_glBindVertexArray(vao);
216         checkGlError("Creating a VAO");
217 #endif
218         
219         // send vertex data to card with given attribute
220         GLfloat vertex_buffer_data[] = {
221                 x1, y1,
222                 x2, y1,
223                 x2, y2,
224                 x1, y2,
225         };
226         GLuint vertex_buffer = createArrayBuffer(sizeof(vertex_buffer_data), vertex_buffer_data);
227         p_glVertexAttribPointer(
228                 attributes.position,              /* attribute */
229                 2,                                /* size */
230                 GL_FLOAT,                         /* type */
231                 GL_FALSE,                         /* normalized? */
232                 0,                                /* stride */
233                 (void*)0                          /* array buffer offset */
234         );
235         checkGlError("Preparing vertex data");
236         p_glEnableVertexAttribArray(attributes.position);
237         checkGlError("Sending vertex data");
238         
239         // same with color data
240         GLfloat color_buffer_data[] = {
241                 red, green, blue,
242                 red, green, blue,
243                 red, green, blue,
244                 red, green, blue,
245         };
246         GLuint color_buffer = createArrayBuffer(sizeof(color_buffer_data), color_buffer_data);
247         p_glVertexAttribPointer(
248                 attributes.color,              /* attribute */
249                 3,                             /* size */
250                 GL_FLOAT,                      /* type */
251                 GL_FALSE,                      /* normalized? */
252                 0,                             /* stride */
253                 (void*)0                       /* array buffer offset */
254         );
255         checkGlError("Preparing color data");
256         p_glEnableVertexAttribArray(attributes.color);
257         checkGlError("Sending color data");
258         
259         // draw
260         glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
261         checkGlError("Drawing");
262         
263         // cleanup
264         p_glDeleteBuffers(1, &vertex_buffer);
265         p_glDeleteBuffers(1, &color_buffer);
266 #ifdef CON_GL3
267         p_glDeleteVertexArrays(1, &vao);
268 #endif
269         checkGlError("Doing cleanup");
270 }