Changes between Version 7 and Version 8 of tutorial

Timestamp:

Jun 26, 2013, 11:32:20 PM (12 years ago)

Author:

leon

Comment:

--

tutorial

@@ -118 +118 @@
  How can we add color to vertices? See [http://www.opengl.org/sdk/docs/man2/xhtml/glColorPointer.xml glColorPointer] and [http://www.opengl.org/sdk/docs/man2/xhtml/glEnableClientState.xml glEnableClientState].
  6. Change background to {{{glClearColor(0.9,1,1,1.0);}}}
+
+
+== Modern OpenGL ==
+Create {{{triangle.c}}} and update {{{Makefile}}}
+{{{
+#!sh
+#include <stdio.h>
+#include <stdlib.h>
+#include <GL/glew.h>
+#include <GL/glut.h>
+
+static const GLchar * vertex_shader[] =
+  {"void main()"
+   "{"
+   "  gl_Position = ftransform();"
+   "}"
+  };
+static const GLchar * fragment_shader[] =
+  {"void main()"
+   "{"
+   " gl_FragColor = vec4(0.4,0.4,0.8,1.0);"
+   "}"
+  };
+
+void setShaders()
+{
+  GLuint v, f, p;
+
+  v = glCreateShader(GL_VERTEX_SHADER);
+  f = glCreateShader(GL_FRAGMENT_SHADER);
+  glShaderSource(v, 1, vertex_shader, NULL);
+  glShaderSource(f, 1, fragment_shader, NULL);
+  glCompileShader(v);
+  glCompileShader(f);
+  p = glCreateProgram();
+  glAttachShader(p,f);
+  glAttachShader(p,v);
+  glLinkProgram(p);
+  glUseProgram(p);
+}
+
+
+enum VAO_IDs { Triangles, NumVAOs };
+enum Buffer_IDs {ArrayBuffer,NumBuffers};
+enum Attrib_IDs { vPosition = 0 };
+GLuint VAOs[NumVAOs];
+GLuint Buffers[NumBuffers];
+#define NumVertices  6 
+
+void init(void)
+{
+  glGenVertexArrays(NumVAOs, VAOs);
+  glBindVertexArray(VAOs[Triangles]);
+  GLfloat vertices[NumVertices][2] = {
+    { -0.90, -0.90 }, // Triangle 1
+    {  0.85, -0.90 },
+    { -0.90,  0.85 },
+    {  0.90, -0.85 }, // Triangle 2
+    {  0.90,  0.90 },
+    { -0.85,  0.90 }
+  };
+  glGenBuffers(NumBuffers, Buffers);
+  glBindBuffer( GL_ARRAY_BUFFER, Buffers[ArrayBuffer]);
+  glBufferData( GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+  glVertexAttribPointer(vPosition, 2, GL_FLOAT, GL_FALSE, 0, (const void*)0);
+  glEnableVertexAttribArray(vPosition);
+}
+
+
+void display(void)
+{
+  glClear(GL_COLOR_BUFFER_BIT);
+  glBindVertexArray(VAOs[Triangles]);
+  glDrawArrays(GL_TRIANGLES, 0, NumVertices);
+  glutSwapBuffers();
+}
+
+int main(int argc, char **argv)
+{
+  glutInit(&argc, argv);
+  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
+  glutCreateWindow("GLSL Intro");
+  glutDisplayFunc(display);
+  glewInit();
+  if (!glewIsSupported("GL_VERSION_2_0"))
+   {
+     printf("GLSL not supported\n");
+     exit(EXIT_FAILURE);
+   }
+  glClearColor(0.9,1.0,1.0,1.0);
+  init();
+  setShaders();
+  glutMainLoop();
+  return 0;
+}
+}}}