HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 143

Chapter 5 E glEvalMesh glEvalMesh glEvalMesh1, glEvalMesh2: compute a one- or two-dimensional grid of points or lines. C Specification void glEvalMesh1( GLenum mode, GLint i1, GLint i2) void glEvalMesh2( GLenum mode, GLint i1, GLint i2, GLint j1, GLint j2) Parameters mode i1, i2 mode i1, i2 j1, j2 In glEvalMesh1, specifies whether to compute a one-dimensional mesh of points or lines. Symbolic constants GL_POINT and GL_LINE are accepted. Specify the first and last integer values for grid domain variable i. In glEvalMesh2, specifies whether to compute a two-dimensional mesh of points, lines, or polygons. Symbolic constants GL_POINT, GL_LINE, and GL_FILL are accepted. Specify the first and last integer values for grid domain variable i. Specify the first and last integer values for grid domain variable j. Description glMapGrid and glEvalMesh are used in tandem to efficiently generate and evaluate a series of evenly-spaced map domain values. glEvalMesh steps through the integer domain of a one- or two-dimensional grid, whose range is the domain of the evaluation maps specified by glMap1 and glMap2. mode determines whether the resulting vertices are connected as points, lines, or filled polygons. In the one-dimensional case, glEvalMesh1, the mesh is generated as if the following code fragment were executed: glBegin (type); for (i = i1; i ≤ i2; i += 1) glEvalCoord1(i-∆u + u1) glEnd(); where ∆u = (u2 − u1) / n 143