Attachment 111312 Details for Bug 87694 – Demo program

Demo program

main.c (text/plain), 5.14 KB, created by nmcveity on 2014-12-25 05:25:19 UTC

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Description:

Filename:

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Creator: nmcveity

Created: 2014-12-25 05:25:19 UTC

Size: 5.14 KB

patch

obsolete

>#include <GL/gl.h>
>#include <GL/glext.h>
>#include <GL/freeglut.h>
>
>
>#include <stdio.h>
>#include <assert.h>
>
>static const char* g_transformVertexShader = "#version 330 \n\
>in float value;\n\
>out float root;\n\
>void main() {\n\
>  root = sqrt(value);\n\
>}";
>
>static const char* g_renderingVertexShader = "#version 330\n\
>in vec3 pos;\n\
>out vec3 pos_out;\n\
>void main() {\n\
>  pos_out = pos;\n\
>}";
>
>static const char* g_renderingGeomShader = "#version 330\n\
>\n\
>layout(points) in;\n\
>layout(triangle_strip, max_vertices=4) out;\n\
>\n\
>in vec3 pos_out[];\n\
>\n\
>void main()\n\
>{\n\
>  gl_Position = vec4(pos_out[0] + vec3(-1,-1, 0), 1);\n\
>  EmitVertex();\n\
>  gl_Position = vec4(pos_out[0] + vec3( 1,-1, 0), 1);\n\
>  EmitVertex();\n\
>  gl_Position = vec4(pos_out[0] + vec3( 1, 1, 0), 1);\n\
>  EmitVertex();\n\
>  gl_Position = vec4(pos_out[0] + vec3(-1, 1, 0), 1);\n\
>  EmitVertex();\n\
>  EndPrimitive();\n\
>}";
>
>static const char* g_renderingFragmentShader = "#version 330\n\
>out vec4 fragmentColor;\n\
>void main() {\n\
>  fragmentColor = vec4(1,1,1,1);\n\
>}";
>
>GLchar info[1024];
>
>GLuint compileShader(GLenum shaderType, const char* script)
>{
>  GLuint shader = glCreateShader(shaderType);
>  glShaderSource(shader, 1, &script, NULL);
>  glCompileShader(shader);
>  GLint status = 0;
>  glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
>  if (status != GL_TRUE)
>  {
>    glGetShaderInfoLog(shader, sizeof(info), NULL, info);
>    printf("While compiling:\n%s", script);
>    printf("Error:\n%s\n", info);
>  }
>  assert(status == GL_TRUE);
>  return shader;
>}
>
>void display(void)
>{
>  glClear(GL_COLOR_BUFFER_BIT);
>
>  // ---------------------------------------------------------
>  // SETUP PROGRAM FOR TRANSFORM FEEDBACK
>
>  GLuint transformProgram = glCreateProgram();
>  glAttachShader(transformProgram, compileShader(GL_VERTEX_SHADER, g_transformVertexShader));
>  const GLchar* varyings[1] = {"root"};
>  glTransformFeedbackVaryings(transformProgram, 1, varyings, GL_INTERLEAVED_ATTRIBS);
>  glLinkProgram(transformProgram);
>  GLint status = 0;
>  glGetProgramiv(transformProgram, GL_LINK_STATUS, &status);
>  assert(status == GL_TRUE);
>
>  // ---------------------------------------------------------
>  // SETUP PROGRAM FOR RENDERING
>
>  GLuint renderingProgram = glCreateProgram();
>  glAttachShader(renderingProgram, compileShader(GL_VERTEX_SHADER, g_renderingVertexShader));
>  glAttachShader(renderingProgram, compileShader(GL_GEOMETRY_SHADER, g_renderingGeomShader));
>  glAttachShader(renderingProgram, compileShader(GL_FRAGMENT_SHADER, g_renderingFragmentShader));
>  glLinkProgram(renderingProgram);
>  glGetProgramiv(renderingProgram, GL_LINK_STATUS, &status);
>  assert(status == GL_TRUE);
>
>  // ---------------------------------------------------------
>  // SETUP INPUT FOR TRANSFORM FEEDBACK
>
>  GLfloat data[4] = {0, 0, 0, 0};
>
>  GLuint outputBuffer;
>  glGenBuffers(1, &outputBuffer);
>  glBindBuffer(GL_ARRAY_BUFFER, outputBuffer);
>  glBufferData(GL_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW);
>
>  GLuint inputBuffer;
>  glGenBuffers(1, &inputBuffer);
>  glBindBuffer(GL_ARRAY_BUFFER, inputBuffer);
>  glBufferData(GL_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW);
>
>  GLuint inputBufferArrayObject;
>  glGenVertexArrays(1, &inputBufferArrayObject);
>  glBindVertexArray(inputBufferArrayObject);
>  GLint attrib = glGetAttribLocation(transformProgram, "value");
>  glVertexAttribPointer(attrib, 1, GL_FLOAT, GL_FALSE, 4, 0);
>  glEnableVertexAttribArray(attrib);
>  glBindVertexArray(0);
>
>  // ---------------------------------------------------------
>  // SETUP RENDERING 
>
>  GLfloat data2[3] = {0, 0, 0};
>
>  GLuint drawBuffer;
>  glGenBuffers(1, &drawBuffer);
>  glBindBuffer(GL_ARRAY_BUFFER, drawBuffer);
>  glBufferData(GL_ARRAY_BUFFER, sizeof(data2), data2, GL_STATIC_DRAW);
>
>  GLuint drawBufferArrayObject;
>  glGenVertexArrays(1, &drawBufferArrayObject);
>  glBindVertexArray(inputBufferArrayObject);
>  attrib = glGetAttribLocation(renderingProgram, "pos");
>  glVertexAttribPointer(attrib, 3, GL_FLOAT, GL_FALSE, sizeof(data2), 0);
>  glEnableVertexAttribArray(attrib);
>  glBindVertexArray(0);
>
>  // ---------------------------------------------------------
>  // DRAW USING GEOMETRY SHADER
>
>  glUseProgram(renderingProgram);
>  glBindVertexArray(drawBufferArrayObject);
>  glDrawArrays(GL_POINTS, 0, 1);
>
>  #ifdef WORKAROUND
>
>  glUseProgram(transformProgram);
>  glBindVertexArray(drawBufferArrayObject);
>  glDrawArrays(GL_POINTS, 0, 1);  
>
>  #endif
>
>  // ---------------------------------------------------------
>  // DRAW CAPTURING TRANSFORM FEEDBACK
>
>  glUseProgram(transformProgram);
>  glBindVertexArray(inputBufferArrayObject);
>  glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, outputBuffer);
>  glBeginTransformFeedback(GL_POINTS);
>  glDrawArrays(GL_POINTS, 0, 1);
>  glEndTransformFeedback();
>
>  glFlush();
>  glFinish();
>  glutSwapBuffers();
>}
>
>int main(int nargs, char** args)
>{
>  glutInit(&nargs, args);
>  glutInitContextVersion(3,2);
>  glutInitContextFlags(GLUT_CORE_PROFILE | GLUT_DEBUG | GLUT_FORWARD_COMPATIBLE);
>  glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
>  glutInitWindowSize(640, 480);
>  glutCreateWindow("Bug");
>  glutDisplayFunc(&display);
>  glEnable(GL_DEPTH_TEST);
>  glClearColor(0, 0, 0, 0);
>  glutMainLoop();
>
>  return EXIT_SUCCESS;
>}

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Attachments on bug 87694: 111311 | 111312 | 111313

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