# From the GLSL 4.40 spec, section 6.4 (Jumps): # # The continue jump is used only in loops. It skips the remainder # of the body of the inner most loop of which it is inside. For # while and do-while loops, this jump is to the next evaluation of # the loop condition-expression from which the loop continues as # previously defined. # # One way that do-while loops might be implemented is to convert them # to infinite loops that terminate in a conditional break (this is # what Mesa does). In such an implementation, an easy way to # implement the proper behaviour of "continue" in a do-while loop is # to replicate the conditional break at the site of the "continue". # For example, this code: # # do { # ... # if (...) { # ... # continue; # } # ... # } while (condition); # # would get translated to: # # loop { # ... # if (...) { # ... # if (!condition) # break; # continue; # } # ... # if (!condition) # break; # } # # However, we must be careful in making this transformation if the # "continue" occurs inside a switch statement, since "break" inside a # switch statement normally exits the switch statement, not the # surrounding loop. # # This test verifies that "continue" behaves properly when invoked # inside a switch statement which is itself inside a do-while loop. [require] GLSL >= 1.30 [vertex shader] #version 130 void main() { gl_Position = gl_Vertex; } [fragment shader] #version 130 void main() { int w = 0; int x = 0; int y = 0; int z = 0; do { // 1st iteration 2nd iteration ++w; // w <- 1 w <- 2 switch (w) { // Jump to case 1 Jump to case 2 case 1: ++x; // x <- 1 break; // Jump to ++z case 2: continue; // Jump to (w < 2) case 3: ++y; // (this case is never executed) break; } ++z; // z <- 1 skipped } while (w < 2); // true false // The loop should execute for two iterations, so w should be 2. X // should be incremented on the first iteration only, so it should // be 1. Y should never be incremented (since w never reaches 3), // so it should be 0. The "continue" should skip ++z on the second // iteration, so z should be 1. if (w == 2 && x == 1 && y == 0 && z == 1) gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0); else gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0); } [test] draw rect -1 -1 2 2 probe all rgba 0.0 1.0 0.0 1.0