OpenGL ES 2.0 Texture loading visual glitch - c++

Question

I have been successful in rendering primitives with a colour component via the shader and also translating them. However, upon attempting to load a texture and render it for the primitive via the shader, the primitives glitch, they should be squares:
As you can see, it successfully loads and applies the texture with the colour component to the single primitive in the scene.
If I then remove the color component, I again have primitives, but oddly, they are scaled by changing the uvs - this should not be the case, only the uvs should scale! (also their origin is offset)
My shader init code:
void renderer::initRendererGfx()
{
shader->compilerShaders();
shader->loadAttribute(#"Position");
shader->loadAttribute(#"SourceColor");
shader->loadAttribute(#"TexCoordIn");
}
Here is my object handler rendering function code:
void renderer::drawRender(glm::mat4 &view, glm::mat4 &projection)
{
//Loop through all objects of base type OBJECT
for(int i=0;i<SceneObjects.size();i++){
if(SceneObjects.size()>0){
shader->bind();//Bind the shader for the rendering of this object
SceneObjects[i]->mv = view * SceneObjects[i]->model;
shader->setUniform(#"modelViewMatrix", SceneObjects[i]->mv);//Calculate object model view
shader->setUniform(#"MVP", projection * SceneObjects[i]->mv);//apply projection transforms to object
glActiveTexture(GL_TEXTURE0); // unneccc in practice
glBindTexture(GL_TEXTURE_2D, SceneObjects[i]->_texture);
shader->setUniform(#"Texture", 0);//Apply the uniform for this instance
SceneObjects[i]->draw();//Draw this object
shader->unbind();//Release the shader for the next object
}
}
}
Here is my sprite buffer initialisation and draw code:
void spriteObject::draw()
{
glVertexAttribPointer((GLuint)0, 3, GL_FLOAT, GL_FALSE, sizeof(SpriteVertex), NULL);
glVertexAttribPointer((GLuint)1, 4, GL_FLOAT, GL_FALSE, sizeof(SpriteVertex) , (GLvoid*) (sizeof(GL_FLOAT) * 3));
glVertexAttribPointer((GLuint)2, 2, GL_FLOAT, GL_FALSE, sizeof(SpriteVertex) , (GLvoid*)(sizeof(GL_FLOAT) * 7));
glDrawElements(GL_TRIANGLE_STRIP, sizeof(SpriteIndices)/sizeof(SpriteIndices[0]), GL_UNSIGNED_BYTE, 0);
}
void spriteObject::initBuffers()
{
glGenBuffers(1, &vertexBufferID);
glBindBuffer(GL_ARRAY_BUFFER, vertexBufferID);
glBufferData(GL_ARRAY_BUFFER, sizeof(SpriteVertices), SpriteVertices, GL_STATIC_DRAW);
glGenBuffers(1, &indexBufferID);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBufferID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(SpriteIndices), SpriteIndices, GL_STATIC_DRAW);
}
Here is the vertex shader:
attribute vec3 Position;
attribute vec4 SourceColor;
varying vec4 DestinationColor;
uniform mat4 projectionMatrix;
uniform mat4 modelViewMatrix;
uniform mat4 MVP;
attribute vec2 TexCoordIn;
varying vec2 TexCoordOut;
void main(void) {
DestinationColor = SourceColor;
gl_Position = MVP * vec4(Position,1.0);
TexCoordOut = TexCoordIn;
}
And finally the fragment shader:
varying lowp vec4 DestinationColor;
varying lowp vec2 TexCoordOut;
uniform sampler2D Texture;
void main(void) {
gl_FragColor = DestinationColor * texture2D(Texture, TexCoordOut);
}
If you want to see any more specifics of certain elements, just ask.
Many thanks.

Answer 1

Are you sure your triangles have the same winding? The winding is the order in which the triangle points are listed ( either clockwise or counter-clockwise ). The winding is used in face culling to determine if the triangle is facing or back-facing.
You can easily check if your triangle are wrongly winded by disabling face culling.
glDisable( GL_CULL_FACE );
More information here ( http://db-in.com/blog/2011/02/all-about-opengl-es-2-x-part-23/#face_culling )