Sign in to follow this  

OpenGL Texture Mapping Issues

Recommended Posts

theJuniorOne    100
Hi, I have been working on a project for school and I am having some problems with texturing a model after I load it from a file. The models seem to all be load and drawn fine, but the textures appear to just be placed anywhere they want on the model itself. as see below.

[attachment=7676:model loader.png]

below is the code involved aswell

Load the Model

[code]ObjectModelType * LoadObjectModel(char *data, int datasize)
Vector3f objboundingboxmin(9999,9999,9999);
Vector3f objboundingboxmax(0,0,0);
char *memoryPositionPtr, *endOfMemoryPtr;
int c=0, polyCtr=0, vertexCtr=0, uvCtr=0, normalCtr=0;
ObjectModelType *theModel;
theModel = (ObjectModelType *)calloc(1,sizeof(ObjectModelType));
memoryPositionPtr = data; // current position and end location pointers
endOfMemoryPtr = data + datasize;
while (memoryPositionPtr != endOfMemoryPtr)
if (*memoryPositionPtr == 'v')
// theModel->VertexCount++; // removed
if (*(memoryPositionPtr+1) == 't') // added
theModel->UVvertexCount++; // added
else if (*(memoryPositionPtr+1) == 'n')
else // added
theModel->VertexCount++; // added
else if (*memoryPositionPtr == 'f')
while (*memoryPositionPtr++ != 0x0A)
//allocate memory for the model data
theModel->VertexArray = (ObjectVertexType *)malloc(sizeof(ObjectVertexType)*theModel->VertexCount);
theModel->NormalArray = (ObjectNormalType *)malloc(sizeof(ObjectNormalType)*theModel->NormalCount);// now allocate the arrays
theModel->UVArray = (ObjectUVType *)malloc(sizeof(ObjectUVType)*theModel->UVvertexCount); // added
theModel->PolygonArray = (ObjectPolygonType *)malloc(sizeof(ObjectPolygonType)*theModel->PolygonCount);

memoryPositionPtr = data; // finally, go back and scan the values
vertexCtr = 1;
polyCtr = uvCtr = 0; // reset values // added modified
while (memoryPositionPtr != endOfMemoryPtr)
if (*memoryPositionPtr=='v') // might be a vertex or a uv coord
if (*(memoryPositionPtr+1) == 't') // it's a uv coord
sscanf(memoryPositionPtr,"vt %f %f",&theModel->UVArray[uvCtr].u,
else if (*(memoryPositionPtr+1) == 'n') // it's a normal coord
sscanf(memoryPositionPtr,"v %f %f %f",&theModel->NormalArray[normalCtr].x,
else // no, it's a vertex
sscanf(memoryPositionPtr,"v %f %f %f",&theModel->VertexArray[vertexCtr].x,
if (objboundingboxmin.x > theModel->VertexArray[vertexCtr].x)
objboundingboxmin.x = theModel->VertexArray[vertexCtr].x;
theModel->bbminx = objboundingboxmin.x;
if (objboundingboxmin.y > theModel->VertexArray[vertexCtr].y)
objboundingboxmin.y = theModel->VertexArray[vertexCtr].y;
if (objboundingboxmin.z > theModel->VertexArray[vertexCtr].z)
objboundingboxmin.z = theModel->VertexArray[vertexCtr].z;
if (objboundingboxmax.x < theModel->VertexArray[vertexCtr].x)
objboundingboxmax.x = theModel->VertexArray[vertexCtr].x;
if (objboundingboxmax.y < theModel->VertexArray[vertexCtr].y)
objboundingboxmax.y = theModel->VertexArray[vertexCtr].y;
if (objboundingboxmax.z < theModel->VertexArray[vertexCtr].z)
objboundingboxmax.z = theModel->VertexArray[vertexCtr].z;
theModel->bbminx = objboundingboxmin.x;
theModel->bbminy = objboundingboxmin.y;
theModel->bbminz = objboundingboxmin.z;
theModel->bbmaxx = objboundingboxmax.x;
theModel->bbmaxy = objboundingboxmax.y;
theModel->bbmaxz = objboundingboxmax.z;
else if (*memoryPositionPtr=='f')
sscanf(memoryPositionPtr,"f %d/%d/%d %d/%d/%d %d/%d/%d ",
&theModel->PolygonArray[polyCtr].Vertex[0],&theModel->PolygonArray[polyCtr].UV[0],&theModel->PolygonArray[polyCtr].Normal[0], // added modified
&theModel->PolygonArray[polyCtr].Vertex[1],&theModel->PolygonArray[polyCtr].UV[1],&theModel->PolygonArray[polyCtr].Normal[1], // added modified
&theModel->PolygonArray[polyCtr].Vertex[2],&theModel->PolygonArray[polyCtr].UV[2],&theModel->PolygonArray[polyCtr].Normal[2]);// added modified

while (*memoryPositionPtr++ != (char) 0x0A)
return theModel;
//#include <direct.h> /* supports _getcwd to get the current working directory if their are problems finding the file */
long LoadObjectFile(const char* filename, char** data)
long bytes = 0;
FILE* theFile;
// char buffer[_MAX_PATH]; _getcwd( buffer, _MAX_PATH ); /* Get the current working directory: */
theFile = fopen(filename, "rt");
if (theFile != NULL)
fseek(theFile, 0, SEEK_END);
long end = ftell(theFile);
fseek(theFile, 0, SEEK_SET);

*data = (char*) malloc(end);
bytes = (long)fread(*data, sizeof(char), (size_t)end, theFile);
return bytes;

Loading and Applying Textures

[code]void Entity::loadImage(const char* filename)
ILuint ilimg;
ilGenImages(1, &ilimg);
//load image
printf("Error: Could load image %s\n", filename);
glGenTextures(1, &image);
glBindTexture(GL_TEXTURE_2D, image);
ILuint bpp = ilGetInteger(IL_IMAGE_BPP);
ILuint width = ilGetInteger(IL_IMAGE_WIDTH);
ILuint height = ilGetInteger(IL_IMAGE_HEIGHT);
ILuint format = ilGetInteger(IL_IMAGE_FORMAT);
ILubyte *data = ilGetData();
glTexImage2D(GL_TEXTURE_2D, 0, bpp, width, height, 0, format,
ilDeleteImages(1, &ilimg);
void Entity :: ApplyTexture()

Drawing the model
[code]void Entity::draw()
/*draw the object in opengl to current location*/

for(long i=0; i<currentPose->PolygonCount;i++)
long v1 = currentPose->PolygonArray[i].Vertex[0];
long v2 = currentPose->PolygonArray[i].Vertex[1];
long v3 = currentPose->PolygonArray[i].Vertex[2];
long uv1 = currentPose->PolygonArray[i].UV[0];
long uv2 = currentPose->PolygonArray[i].UV[1];
long uv3 = currentPose->PolygonArray[i].UV[2];
long vn1 = currentPose->PolygonArray[i].Normal[0];
long vn2 = currentPose->PolygonArray[i].Normal[1];
long vn3 = currentPose->PolygonArray[i].Normal[2];

//point 1
glVertex3f(currentPose->VertexArray[v1].x,currentPose->VertexArray[v1].y,currentPose->VertexArray[v1].z );

//point 2
glVertex3f(currentPose->VertexArray[v2].x,currentPose->VertexArray[v2].y,currentPose->VertexArray[v2].z );

//point 3
glVertex3f(currentPose->VertexArray[v3].x,currentPose->VertexArray[v3].y,currentPose->VertexArray[v3].z );


any help would really be appreciated, I have spent many long nights trying to figure this out, also let me know If you want to me to include any other code. Thanks in advance.

Share this post

Link to post
Share on other sites
theJuniorOne    100
Yeah that is what I figured but I cant figure out why and I have asked my artist over and over again if its UV mapped correctly and according to him and maya it is. So I dont know why it is getting incorrect values for the UV's

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Similar Content

    • By Kjell Andersson
      I'm trying to get some legacy OpenGL code to run with a shader pipeline,
      The legacy code uses glVertexPointer(), glColorPointer(), glNormalPointer() and glTexCoordPointer() to supply the vertex information.
      I know that it should be using setVertexAttribPointer() etc to clearly define the layout but that is not an option right now since the legacy code can't be modified to that extent.
      I've got a version 330 vertex shader to somewhat work:
      #version 330 uniform mat4 osg_ModelViewProjectionMatrix; uniform mat4 osg_ModelViewMatrix; layout(location = 0) in vec4 Vertex; layout(location = 2) in vec4 Normal; // Velocity layout(location = 3) in vec3 TexCoord; // TODO: is this the right layout location? out VertexData { vec4 color; vec3 velocity; float size; } VertexOut; void main(void) { vec4 p0 = Vertex; vec4 p1 = Vertex + vec4(Normal.x, Normal.y, Normal.z, 0.0f); vec3 velocity = (osg_ModelViewProjectionMatrix * p1 - osg_ModelViewProjectionMatrix * p0).xyz; VertexOut.velocity = velocity; VertexOut.size = TexCoord.y; gl_Position = osg_ModelViewMatrix * Vertex; } What works is the Vertex and Normal information that the legacy C++ OpenGL code seem to provide in layout location 0 and 2. This is fine.
      What I'm not getting to work is the TexCoord information that is supplied by a glTexCoordPointer() call in C++.
      What layout location is the old standard pipeline using for glTexCoordPointer()? Or is this undefined?
      Side note: I'm trying to get an OpenSceneGraph 3.4.0 particle system to use custom vertex, geometry and fragment shaders for rendering the particles.
    • By markshaw001
      Hi i am new to this forum  i wanted to ask for help from all of you i want to generate real time terrain using a 32 bit heightmap i am good at c++ and have started learning Opengl as i am very interested in making landscapes in opengl i have looked around the internet for help about this topic but i am not getting the hang of the concepts and what they are doing can some here suggests me some good resources for making terrain engine please for example like tutorials,books etc so that i can understand the whole concept of terrain generation.
    • By KarimIO
      Hey guys. I'm trying to get my application to work on my Nvidia GTX 970 desktop. It currently works on my Intel HD 3000 laptop, but on the desktop, every bind textures specifically from framebuffers, I get half a second of lag. This is done 4 times as I have three RGBA textures and one depth 32F buffer. I tried to use debugging software for the first time - RenderDoc only shows SwapBuffers() and no OGL calls, while Nvidia Nsight crashes upon execution, so neither are helpful. Without binding it runs regularly. This does not happen with non-framebuffer binds.
      GLFramebuffer::GLFramebuffer(FramebufferCreateInfo createInfo) { glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); textures = new GLuint[createInfo.numColorTargets]; glGenTextures(createInfo.numColorTargets, textures); GLenum *DrawBuffers = new GLenum[createInfo.numColorTargets]; for (uint32_t i = 0; i < createInfo.numColorTargets; i++) { glBindTexture(GL_TEXTURE_2D, textures[i]); GLint internalFormat; GLenum format; TranslateFormats(createInfo.colorFormats[i], format, internalFormat); // returns GL_RGBA and GL_RGBA glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, createInfo.width, createInfo.height, 0, format, GL_FLOAT, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); DrawBuffers[i] = GL_COLOR_ATTACHMENT0 + i; glBindTexture(GL_TEXTURE_2D, 0); glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + i, textures[i], 0); } if (createInfo.depthFormat != FORMAT_DEPTH_NONE) { GLenum depthFormat; switch (createInfo.depthFormat) { case FORMAT_DEPTH_16: depthFormat = GL_DEPTH_COMPONENT16; break; case FORMAT_DEPTH_24: depthFormat = GL_DEPTH_COMPONENT24; break; case FORMAT_DEPTH_32: depthFormat = GL_DEPTH_COMPONENT32; break; case FORMAT_DEPTH_24_STENCIL_8: depthFormat = GL_DEPTH24_STENCIL8; break; case FORMAT_DEPTH_32_STENCIL_8: depthFormat = GL_DEPTH32F_STENCIL8; break; } glGenTextures(1, &depthrenderbuffer); glBindTexture(GL_TEXTURE_2D, depthrenderbuffer); glTexImage2D(GL_TEXTURE_2D, 0, depthFormat, createInfo.width, createInfo.height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glBindTexture(GL_TEXTURE_2D, 0); glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, depthrenderbuffer, 0); } if (createInfo.numColorTargets > 0) glDrawBuffers(createInfo.numColorTargets, DrawBuffers); else glDrawBuffer(GL_NONE); if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) std::cout << "Framebuffer Incomplete\n"; glBindFramebuffer(GL_FRAMEBUFFER, 0); width = createInfo.width; height = createInfo.height; } // ... // FBO Creation FramebufferCreateInfo gbufferCI; gbufferCI.colorFormats =; gbufferCI.depthFormat = FORMAT_DEPTH_32; gbufferCI.numColorTargets = gbufferCFs.size(); gbufferCI.width = engine.settings.resolutionX; gbufferCI.height = engine.settings.resolutionY; gbufferCI.renderPass = nullptr; gbuffer = graphicsWrapper->CreateFramebuffer(gbufferCI); // Bind glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo); // Draw here... // Bind to textures glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, textures[0]); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, textures[1]); glActiveTexture(GL_TEXTURE2); glBindTexture(GL_TEXTURE_2D, textures[2]); glActiveTexture(GL_TEXTURE3); glBindTexture(GL_TEXTURE_2D, depthrenderbuffer); Here is an extract of my code. I can't think of anything else to include. I've really been butting my head into a wall trying to think of a reason but I can think of none and all my research yields nothing. Thanks in advance!
    • By Adrianensis
      Hi everyone, I've shared my 2D Game Engine source code. It's the result of 4 years working on it (and I still continue improving features ) and I want to share with the community. You can see some videos on youtube and some demo gifs on my twitter account.
      This Engine has been developed as End-of-Degree Project and it is coded in Javascript, WebGL and GLSL. The engine is written from scratch.
      This is not a professional engine but it's for learning purposes, so anyone can review the code an learn basis about graphics, physics or game engine architecture. Source code on this GitHub repository.
      I'm available for a good conversation about Game Engine / Graphics Programming
    • By C0dR
      I would like to introduce the first version of my physically based camera rendering library, written in C++, called PhysiCam.
      Physicam is an open source OpenGL C++ library, which provides physically based camera rendering and parameters. It is based on OpenGL and designed to be used as either static library or dynamic library and can be integrated in existing applications.
      The following features are implemented:
      Physically based sensor and focal length calculation Autoexposure Manual exposure Lense distortion Bloom (influenced by ISO, Shutter Speed, Sensor type etc.) Bokeh (influenced by Aperture, Sensor type and focal length) Tonemapping  
      You can find the repository at
      I would be happy about feedback, suggestions or contributions.

  • Popular Now