Hello everyone,
I have finally finished my Wavefront OBJ parser (sort of), and trying to test a cube shape, which is unfortunately failing for me.
To begin with i only want to draw the cube actual cube, i dont care about textures or normals!
So this is my Wavefront OBJ file:
v -0.307796 0.00433517 0
v 0.299126 0.00433517 0
v 0.299126 0.00433517 0.48337
v -0.307796 0.00433517 0.48337
v -0.307796 0.364153 0.48337
v 0.299126 0.364153 0.48337
v 0.299126 0.364153 0
v -0.307796 0.364153 0
f 7/1/1 3/2/2 2/3/3
f 3/4/4 7/5/5 6/6/6
f 5/7/7 1/8/8 4/9/9
f 1/10/10 5/11/11 8/12/12
f 7/13/13 1/14/14 8/15/15
f 1/16/16 7/17/17 2/18/18
f 3/19/19 5/20/20 4/21/21
f 5/22/22 3/23/23 6/24/24
f 5/25/25 7/26/26 8/27/27
f 7/28/28 5/29/29 6/30/30
f 3/31/31 1/32/32 2/33/33
f 1/34/34 3/35/35 4/36/36
So basically the faces is written in following form: f v1/vt1/vn1 v2/vt2/vn2 v3/vt3/vn3 …
Since i only want the index of the vertices (dont care for normals and textures) i save vertices and my indices as:
const Vertex Vertices[] = {
{-0.307796,0.00433517,0},
{0.299126,0.00433517,0},
{0.299126,0.00433517,0.48337},
{-0.307796,0.00433517,0.48337},
{-0.307796,0.364153,0.48337},
{0.299126,0.364153,0.48337},
{0.299126,0.364153,0},
{-0.307796,0.364153,0}
};
const GLubyte Indices[] = {
7, 3, 2,
3, 7, 6,
5, 1, 4,
1, 5, 8,
7, 1, 8,
1, 7, 2,
3, 5, 4,
5, 3, 6,
5, 7, 8,
7, 5, 6,
3, 1, 2,
1, 3, 4
};
And all the OpenGL stuff (objective-C):
- (void)setupRenderBuffer {
glGenRenderbuffers(1, &_colorRenderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, _colorRenderBuffer);
[_context renderbufferStorage:GL_RENDERBUFFER fromDrawable:_eaglLayer];
}
- (void)setupDepthBuffer {
glGenRenderbuffers(1, &_depthRenderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, _depthRenderBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, self.frame.size.width, self.frame.size.height);
}
- (void)setupFrameBuffer {
GLuint framebuffer;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, _colorRenderBuffer);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _depthRenderBuffer);
}
- (GLuint)compileShader:(NSString*)shaderName withType:(GLenum)shaderType {
// 1
NSString* shaderPath = [[NSBundle mainBundle] pathForResource:shaderName ofType:@"glsl"];
NSError* error;
NSString* shaderString = [NSString stringWithContentsOfFile:shaderPath encoding:NSUTF8StringEncoding error:&error];
if (!shaderString) {
NSLog(@"Error loading shader: %@", error.localizedDescription);
exit(1);
}
// 2
GLuint shaderHandle = glCreateShader(shaderType);
// 3
const char * shaderStringUTF8 = [shaderString UTF8String];
int shaderStringLength = [shaderString length];
glShaderSource(shaderHandle, 1, &shaderStringUTF8, &shaderStringLength);
// 4
glCompileShader(shaderHandle);
// 5
GLint compileSuccess;
glGetShaderiv(shaderHandle, GL_COMPILE_STATUS, &compileSuccess);
if (compileSuccess == GL_FALSE) {
GLchar messages[256];
glGetShaderInfoLog(shaderHandle, sizeof(messages), 0, &messages[0]);
NSString *messageString = [NSString stringWithUTF8String:messages];
NSLog(@"%@", messageString);
exit(1);
}
return shaderHandle;
}
- (void)compileShaders {
// 1
GLuint vertexShader = [self compileShader:@"SimpleVertex" withType:GL_VERTEX_SHADER];
GLuint fragmentShader = [self compileShader:@"SimpleFragment" withType:GL_FRAGMENT_SHADER];
// 2
GLuint programHandle = glCreateProgram();
glAttachShader(programHandle, vertexShader);
glAttachShader(programHandle, fragmentShader);
glLinkProgram(programHandle);
// 3
GLint linkSuccess;
glGetProgramiv(programHandle, GL_LINK_STATUS, &linkSuccess);
if (linkSuccess == GL_FALSE) {
GLchar messages[256];
glGetProgramInfoLog(programHandle, sizeof(messages), 0, &messages[0]);
NSString *messageString = [NSString stringWithUTF8String:messages];
NSLog(@"%@", messageString);
exit(1);
}
// 4
glUseProgram(programHandle);
// 5
_positionSlot = glGetAttribLocation(programHandle, "Position");
_colorSlot = glGetAttribLocation(programHandle, "SourceColor");
glEnableVertexAttribArray(_positionSlot);
glEnableVertexAttribArray(_colorSlot);
_projectionUniform = glGetUniformLocation(programHandle, "Projection");
_modelViewUniform = glGetUniformLocation(programHandle, "Modelview");
}
- (void)setupVBOs {
GLuint vertexBuffer;
glGenBuffers(1, &vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
GLuint indexBuffer;
glGenBuffers(1, &indexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(Indices), Indices, GL_STATIC_DRAW);
}
- (void)render:(CADisplayLink*)displayLink {
glClearColor(0, 104.0/255.0, 55.0/255.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
CC3GLMatrix *projection = [CC3GLMatrix matrix];
float h = 4.0f * self.frame.size.height / self.frame.size.width;
[projection populateFromFrustumLeft:-2 andRight:2 andBottom:-h/2 andTop:h/2 andNear:4 andFar:10];
glUniformMatrix4fv(_projectionUniform, 1, 0, projection.glMatrix);
CC3GLMatrix *modelView = [CC3GLMatrix matrix];
[modelView populateFromTranslation:CC3VectorMake(sin(CACurrentMediaTime()), 0, -7)];
_currentRotation += displayLink.duration * 90;
[modelView rotateBy:CC3VectorMake(_currentRotation, _currentRotation, 0)];
glUniformMatrix4fv(_modelViewUniform, 1, 0, modelView.glMatrix);
// 1
glViewport(0, 0, self.frame.size.width, self.frame.size.height);
// 2
glVertexAttribPointer(_positionSlot, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), 0);
glVertexAttribPointer(_colorSlot, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*) (sizeof(float) * 3));
// 3
// glDrawElements(GL_TRIANGLES, sizeof(Indices)/sizeof(Indices[0]), GL_UNSIGNED_BYTE, 0);
glDrawElements(GL_TRIANGLES, sizeof(Indices), GL_UNSIGNED_BYTE, 0);
[_context presentRenderbuffer:GL_RENDERBUFFER];
}
So to get back to the actual issue, i do not exactly get what should have looked like a actual cube. It looks like some bits and pieces are missing in terms of connections to vertices.
I have taken a screenshot to show what i am viewing:
[ATTACH=CONFIG]176[/ATTACH]