1 //========================================================================
2 // Multisample anti-aliasing test
3 // Copyright (c) Camilla Löwy <elmindreda@glfw.org>
4 //
5 // This software is provided 'as-is', without any express or implied
6 // warranty. In no event will the authors be held liable for any damages
7 // arising from the use of this software.
8 //
9 // Permission is granted to anyone to use this software for any purpose,
10 // including commercial applications, and to alter it and redistribute it
11 // freely, subject to the following restrictions:
12 //
13 // 1. The origin of this software must not be misrepresented; you must not
14 // claim that you wrote the original software. If you use this software
15 // in a product, an acknowledgment in the product documentation would
16 // be appreciated but is not required.
17 //
18 // 2. Altered source versions must be plainly marked as such, and must not
19 // be misrepresented as being the original software.
20 //
21 // 3. This notice may not be removed or altered from any source
22 // distribution.
23 //
24 //========================================================================
25 //
26 // This test renders two high contrast, slowly rotating quads, one aliased
27 // and one (hopefully) anti-aliased, thus allowing for visual verification
28 // of whether MSAA is indeed enabled
29 //
30 //========================================================================
31
32 #define GLAD_GL_IMPLEMENTATION
33 #include <glad/gl.h>
34 #define GLFW_INCLUDE_NONE
35 #include <GLFW/glfw3.h>
36
37 #if defined(_MSC_VER)
38 // Make MS math.h define M_PI
39 #define _USE_MATH_DEFINES
40 #endif
41
42 #include "linmath.h"
43
44 #include <stdio.h>
45 #include <stdlib.h>
46
47 #include "getopt.h"
48
49 static const vec2 vertices[4] =
50 {
51 { -0.6f, -0.6f },
52 { 0.6f, -0.6f },
53 { 0.6f, 0.6f },
54 { -0.6f, 0.6f }
55 };
56
57 static const char* vertex_shader_text =
58 "#version 110\n"
59 "uniform mat4 MVP;\n"
60 "attribute vec2 vPos;\n"
61 "void main()\n"
62 "{\n"
63 " gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
64 "}\n";
65
66 static const char* fragment_shader_text =
67 "#version 110\n"
68 "void main()\n"
69 "{\n"
70 " gl_FragColor = vec4(1.0);\n"
71 "}\n";
72
error_callback(int error,const char * description)73 static void error_callback(int error, const char* description)
74 {
75 fprintf(stderr, "Error: %s\n", description);
76 }
77
key_callback(GLFWwindow * window,int key,int scancode,int action,int mods)78 static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
79 {
80 if (action != GLFW_PRESS)
81 return;
82
83 switch (key)
84 {
85 case GLFW_KEY_SPACE:
86 glfwSetTime(0.0);
87 break;
88 case GLFW_KEY_ESCAPE:
89 glfwSetWindowShouldClose(window, GLFW_TRUE);
90 break;
91 }
92 }
93
usage(void)94 static void usage(void)
95 {
96 printf("Usage: msaa [-h] [-s SAMPLES]\n");
97 }
98
main(int argc,char ** argv)99 int main(int argc, char** argv)
100 {
101 int ch, samples = 4;
102 GLFWwindow* window;
103 GLuint vertex_buffer, vertex_shader, fragment_shader, program;
104 GLint mvp_location, vpos_location;
105
106 while ((ch = getopt(argc, argv, "hs:")) != -1)
107 {
108 switch (ch)
109 {
110 case 'h':
111 usage();
112 exit(EXIT_SUCCESS);
113 case 's':
114 samples = atoi(optarg);
115 break;
116 default:
117 usage();
118 exit(EXIT_FAILURE);
119 }
120 }
121
122 glfwSetErrorCallback(error_callback);
123
124 if (!glfwInit())
125 exit(EXIT_FAILURE);
126
127 if (samples)
128 printf("Requesting MSAA with %i samples\n", samples);
129 else
130 printf("Requesting that MSAA not be available\n");
131
132 glfwWindowHint(GLFW_SAMPLES, samples);
133 glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
134 glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
135
136 window = glfwCreateWindow(800, 400, "Aliasing Detector", NULL, NULL);
137 if (!window)
138 {
139 glfwTerminate();
140 exit(EXIT_FAILURE);
141 }
142
143 glfwSetKeyCallback(window, key_callback);
144
145 glfwMakeContextCurrent(window);
146 gladLoadGL(glfwGetProcAddress);
147 glfwSwapInterval(1);
148
149 glGetIntegerv(GL_SAMPLES, &samples);
150 if (samples)
151 printf("Context reports MSAA is available with %i samples\n", samples);
152 else
153 printf("Context reports MSAA is unavailable\n");
154
155 glGenBuffers(1, &vertex_buffer);
156 glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
157 glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
158
159 vertex_shader = glCreateShader(GL_VERTEX_SHADER);
160 glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
161 glCompileShader(vertex_shader);
162
163 fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
164 glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
165 glCompileShader(fragment_shader);
166
167 program = glCreateProgram();
168 glAttachShader(program, vertex_shader);
169 glAttachShader(program, fragment_shader);
170 glLinkProgram(program);
171
172 mvp_location = glGetUniformLocation(program, "MVP");
173 vpos_location = glGetAttribLocation(program, "vPos");
174
175 glEnableVertexAttribArray(vpos_location);
176 glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
177 sizeof(vertices[0]), (void*) 0);
178
179 while (!glfwWindowShouldClose(window))
180 {
181 float ratio;
182 int width, height;
183 mat4x4 m, p, mvp;
184 const double angle = glfwGetTime() * M_PI / 180.0;
185
186 glfwGetFramebufferSize(window, &width, &height);
187 ratio = width / (float) height;
188
189 glViewport(0, 0, width, height);
190 glClear(GL_COLOR_BUFFER_BIT);
191
192 glUseProgram(program);
193
194 mat4x4_ortho(p, -ratio, ratio, -1.f, 1.f, 0.f, 1.f);
195
196 mat4x4_translate(m, -1.f, 0.f, 0.f);
197 mat4x4_rotate_Z(m, m, (float) angle);
198 mat4x4_mul(mvp, p, m);
199
200 glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
201 glDisable(GL_MULTISAMPLE);
202 glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
203
204 mat4x4_translate(m, 1.f, 0.f, 0.f);
205 mat4x4_rotate_Z(m, m, (float) angle);
206 mat4x4_mul(mvp, p, m);
207
208 glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
209 glEnable(GL_MULTISAMPLE);
210 glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
211
212 glfwSwapBuffers(window);
213 glfwPollEvents();
214 }
215
216 glfwDestroyWindow(window);
217
218 glfwTerminate();
219 exit(EXIT_SUCCESS);
220 }
221
222