-(void) drawSmoothLine: (CGPoint) pos1: (CGPoint) pos2: (ccColor4F) someColor
{
[shaderProgram_ use];
[shaderProgram_ setUniformsForBuiltins];
[shaderProgram_ setUniformLocation:-1 with4fv:(GLfloat*) &someColor.r count:1];
ccGLEnableVertexAttribs(kCCVertexAttribFlag_Position | kCCVertexAttribFlag_Color );
GLfloat lineVertices[12];
CGPoint dir, tan;
float width = 1.2f;
dir.x = pos2.x - pos1.x;
dir.y = pos2.y - pos1.y;
float len = sqrtf(dir.x*dir.x+dir.y*dir.y);
if(len<0.00001)
return;
dir.x = dir.x/len;
dir.y = dir.y/len;
tan.x = -width*dir.y;
tan.y = width*dir.x;
lineVertices[0] = pos1.x + tan.x;
lineVertices[1] = pos1.y + tan.y;
lineVertices[2] = pos2.x + tan.x;
lineVertices[3] = pos2.y + tan.y;
lineVertices[4] = pos1.x;
lineVertices[5] = pos1.y;
lineVertices[6] = pos2.x;
lineVertices[7] = pos2.y;
lineVertices[8] = pos1.x - tan.x;
lineVertices[9] = pos1.y - tan.y;
lineVertices[10] = pos2.x - tan.x;
lineVertices[11] = pos2.y - tan.y;
ccColor4F vertices[6];
ccColor4F color1 = {rCol, gCol, bCol, 0};
ccColor4F color2 = {rCol, gCol, bCol, opacity};
vertices[0] = color1;
vertices[1] = color1;
vertices[2] = color2;
vertices[3] = color2;
vertices[4] = color1;
vertices[5] = color1;
glVertexAttribPointer(kCCVertexAttrib_Position, 2, GL_FLOAT, GL_FALSE, 0, lineVertices);
glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_FLOAT, GL_FALSE, 0, vertices);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 6);
}
Now you may notice that when you draw lines there are tiny dots that appear in the line, well that's because of the way the triangles are drawn and I'll get into that in the next post and how to get rid of it! Also, if you use the above, make sure to go into ccConfig.h and enable CC_ENABLE_GL_STATE_CACHE, I got a huge performance improvement from that. In the above method, the values rCol, gCol and bCol are just the current rgb values which you can manually modify or get from the passed in ccColor4f value.
Pavan
Dutch Cheese Games
